Secondary battery

Abstract

A secondary battery includes: an exterior member; a battery element housed inside the exterior member, including a first electrode and a second electrode; an exterior terminal mounted to the exterior member and insulated from the exterior member; and a connection wire connected to each of the first electrode and the exterior terminal. A portion of the connection wire is insulated from each of the exterior member and the second electrode, and is sandwiched by the exterior member and the battery element.

Description

Technical Field

[0001] This technology relates to a secondary battery. Background Technology

[0002] With the widespread adoption of mobile phones and other electronic devices, the development of secondary batteries—small, lightweight power sources capable of high energy density—is underway. These secondary batteries typically contain a positive electrode, a negative electrode, and an electrolyte housed within an external component. Various studies have been conducted regarding the structure of these secondary batteries.

[0003] Specifically, to achieve excellent safety in cylindrical secondary batteries, a positive current collector connector is connected to each of the positive plate and the positive terminal, and this positive current collector connector is bent into an S-shape (e.g., see Patent Document 1). In cylindrical secondary batteries, to prevent internal short circuits, a lead sheet is connected to each of the plate and the sealing plate, and this lead sheet is bent into a generally V-shape (e.g., see Patent Document 2). In button-type secondary batteries, to improve durability against mechanical loads, a composite (spiral roller) containing two electrodes and a separator is housed inside the cup-shaped portion and the cover portion, and an output conductor is connected to each of one of the electrodes and each of the cover portion (e.g., see Patent Document 3).

[0004] Existing technical documents

[0005] Patent documents

[0006] Patent Document 1: Japanese Patent Application Publication No. 2013-097903

[0007] Patent Document 2: Japanese Patent Application Publication No. 10-154505

[0008] Patent Document 3: Japanese Patent Publication No. 2012-517658 Summary of the Invention

[0009] Various studies have been conducted to improve the performance of the secondary battery, but its physical durability is still insufficient, leaving room for improvement.

[0010] This technology was developed in view of the above-mentioned problems, and its purpose is to provide a secondary battery that can achieve excellent physical durability.

[0011] One embodiment of the present technology provides a secondary battery comprising: an outer casing; a battery element housed within the outer casing, including a first electrode and a second electrode; an external terminal mounted on the outer casing and insulated from the outer casing; and a connecting wire connected to each of the first electrode and the external terminal, a portion of the connecting wire being insulated from each of the outer casing and the second electrode and being held by the outer casing and the battery element.

[0012] According to one embodiment of the present technology, a secondary battery including a battery element comprising a first electrode and a second electrode is housed inside an outer casing, is insulated from the outer casing, and has external terminals mounted on the outer casing. A connecting wire is connected to each of the first electrode and the external terminals. A portion of the connecting wire is insulated from each of the outer casing and the second electrode and is clamped by the outer casing and the battery element, thus achieving excellent physical durability.

[0013] It should be noted that the effect of this technology is not limited to the effect described herein, but can be any of the series of effects associated with this technology described later. Attached Figure Description

[0014] Figure 1 This is a perspective view showing the structure of a secondary battery in one embodiment of the present technology.

[0015] Figure 2 It means Figure 1 The diagram shows a cross-sectional view of the secondary battery structure.

[0016] Figure 3 It means Figure 2 The diagram shows a cross-sectional view of the structure of the battery element.

[0017] Figure 4 This is a three-dimensional diagram showing the structure of the outer can used in the manufacturing process of secondary batteries.

[0018] Figure 5 This is a cross-sectional view showing the structure of the outer can to illustrate the manufacturing process of secondary batteries.

[0019] Figure 6 This is a cross-sectional view showing the structure of the secondary battery in Modified Example 3.

[0020] Figure 7 This is a cross-sectional view showing the structure of the secondary battery in Modified Example 4.

[0021] Figure 8 This is a cross-sectional view showing the structure of the secondary battery in Modified Example 5.

[0022] Figure 9 This is a cross-sectional view showing the structure of the secondary battery in Modified Example 6.

[0023] Figure 10 This is a cross-sectional view showing the structure of the secondary battery in modified example 7.

[0024] Figure 11 This is a cross-sectional view showing the structure of the secondary battery in Modified Example 8.

[0025] Figure 12 This is a cross-sectional view showing the structure of the secondary battery in modified example 9.

[0026] Figure 13 This is a cross-sectional view showing the structure of the secondary battery in Modified Example 10.

[0027] Figure 14 This is a cross-sectional view showing the structure of the secondary battery in Modified Example 11.

[0028] Figure 15 This is a cross-sectional view showing the structure of the secondary battery in Modified Example 12.

[0029] Figure 16 This is a cross-sectional view showing the structure of the secondary battery in Modified Example 13.

[0030] Figure 17 This is a cross-sectional view showing the structure of the secondary battery in Modified Example 14.

[0031] Figure 18 This is a cross-sectional view showing the structure of the secondary battery in Modified Example 15.

[0032] Figure 19 This is a cross-sectional view showing the structure of the secondary battery in Modified Example 16.

[0033] Figure 20 This is a cross-sectional view showing the structure of the secondary battery in Modified Example 17. Detailed Implementation

[0034] The following is a detailed description of one embodiment of the present technology with reference to the accompanying drawings. It should be noted that the description is presented in the following order.

[0035] 1. Secondary battery

[0036] 1-1. Structure

[0037] 1-2. Actions

[0038] 1-3. Manufacturing Method

[0039] 1-4. Functions and Effects

[0040] 2. Variations

[0041] <1. Secondary Battery>

[0042] First, a secondary battery according to one embodiment of this technology will be described.

[0043] The secondary battery described herein has a flat, cylindrical three-dimensional shape, referred to as so-called coin-type and button-type, etc. As described later, the secondary battery has a pair of opposing bottoms and a sidewall portion located between the pair of bottoms, in which the height is smaller than the outer diameter. The "outer diameter" refers to the diameter of each of the pair of bottoms (maximum diameter), and the "height" refers to the distance from the surface of one bottom to the surface of the other bottom (maximum distance).

[0044] The charging and discharging principle of a secondary battery is not particularly limited. The following explanation concerns the case where battery capacity is obtained by utilizing the intercalation and deintercalation of electrode reactants. This secondary battery includes a positive electrode, a negative electrode, and an electrolyte. In this secondary battery, to prevent the deposition of electrode reactants on the surface of the negative electrode during charging, the charging capacity of the negative electrode is greater than the discharging capacity of the positive electrode. That is, the electrochemical capacity per unit area of ​​the negative electrode is set to be greater than that of the positive electrode per unit area.

[0045] There are no particular restrictions on the types of substances used in the electrode reactions. Specifically, they are light metals such as alkali metals and alkaline earth metals. Alkali metals include lithium, sodium, and potassium, while alkaline earth metals include beryllium, magnesium, and calcium.

[0046] The following example uses lithium as the electrode reactant. A secondary battery that utilizes the insertion and extraction of lithium to obtain battery capacity is called a lithium-ion secondary battery. In this lithium-ion secondary battery, lithium is inserted and extracted in an ionic state.

[0047] <1-1. Structure>

[0048] Figure 1 The three-dimensional structure of a secondary battery is shown. Figure 2 It shows Figure 1 The cross-sectional structure of the secondary battery is shown. Figure 3 It shows Figure 2 The cross-sectional structure of the battery element 40 is shown. Additionally, in Figure 2 In the diagram, the positive lead 51 is marked with a shaded area, and... Figure 3 In the image, only a portion of the cross-sectional structure of the battery element 40 is magnified.

[0049] For convenience, the following will be... Figure 1 as well as Figure 2 The top side of each will be described as the top side of the secondary battery, and... Figure 1 as well as Figure 2 The bottom side of each will be described as the bottom side of the secondary battery.

[0050] The secondary batteries described here are as follows: Figure 1As shown, it has a three-dimensional shape with a height H smaller than its outer diameter D, that is, a flat and cylindrical three-dimensional shape. Here, the three-dimensional shape of the secondary battery is flat and cylindrical.

[0051] The size of the secondary battery is not particularly limited. For example, the outer diameter D = 3mm to 30mm, and the height H = 0.5mm to 70mm. Furthermore, the ratio of the outer diameter D to the height H (D / H) is greater than 1. There is no particular upper limit to this ratio (D / H), but it is preferably 25 or less.

[0052] like Figures 1 to 3 As shown, the secondary battery includes an outer canister 10, external terminals 20, battery elements 40, and a positive lead 51. The secondary battery also includes a gasket 30, a negative lead 52, a sealant 61, and insulating films 62 and 63.

[0053] [Outer packaging can]

[0054] like Figure 1 as well as Figure 2 As shown, the outer can 10 is a hollow outer component that houses battery components 40, etc.

[0055] Here, the outer can 10 has a flat and cylindrical three-dimensional shape, based on the three-dimensional shape of a flat and cylindrical secondary battery. Therefore, the outer can 10 has a pair of opposing bottoms M1 and M2 and a sidewall portion M3 located between the bottoms M1 and M2. The upper end of the sidewall portion M3 is connected to the bottom M1, and the lower end of the sidewall portion M3 is connected to the bottom M2. As described above, since the outer can 10 is cylindrical, the planar shape of each of the bottoms M1 and M2 is circular, and the surface of the sidewall portion M3 is a convex curved surface.

[0056] Additionally, the outer can 10 includes a receiving portion 11 and a lid 12 welded together, the receiving portion 11 being sealed by the lid 12. That is, the lid 12 is welded to the receiving portion 11.

[0057] The storage section 11 is a flat, cylindrical storage component that houses the battery element 40 and the like. The storage section 11 has a hollow structure that is open at the top and closed at the bottom, and therefore has an opening 11K at its top.

[0058] The cover 12 is a generally disc-shaped cover component that closes the opening 11K of the storage portion 11 and has a through hole 12K. As described above, the cover 12 is welded to the storage portion 11 at the opening 11K. Since an external terminal 20 is mounted on the cover 12, the cover 12 supports the external terminal 20.

[0059] Here, because the cover portion 12 is bent in a manner that partially protrudes towards the interior of the receiving portion 11, the cover portion 12 is partially recessed. In this case, a portion of the cover portion 12 is bent in a manner that forms a step towards the center of the cover portion 12. Thus, the cover portion 12 includes a protrusion 12P formed by bending the cover portion 12 in a manner that partially protrudes towards the interior of the receiving portion 11, and includes a recessed portion 12H formed by the protrusion 12P. It should be noted that a through hole 12K is provided on the protrusion 12P (or the recessed portion 12H).

[0060] As described above, the outer can 10 is a welded can formed by welding two parts (the receiving part 11 and the lid part 12) together. As a result, the welded outer can 10 is physically a single part as a whole, and therefore cannot be separated into two parts (the receiving part 11 and the lid part 12) afterward.

[0061] The outer can 10 of the welded can does not have folded parts and does not have two or more parts that overlap.

[0062] The phrase "not having mutually folding parts" means that a portion of the outer can 10 is not manufactured to fold together. Furthermore, "not having parts with more than two overlapping" means that after the secondary battery is completed, since the outer can 10 is physically a single component, it cannot be subsequently separated into more than two components. In other words, the outer can 10 is not in a state where two or more components overlap and are combined to allow for subsequent separation.

[0063] In particular, the outer can 10, which is a welded can, is different from a rolled can formed using riveting; it is a so-called non-rolled can. This is because the internal component space volume of the outer can 10 increases, thus increasing the energy density per unit volume of the secondary battery. This "component space volume" refers to the volume (effective volume) of the internal space of the outer can 10 that can accommodate the battery components 40 participating in the charge-discharge reaction.

[0064] Here, the outer can 10 (containing part 11 and cover part 12) is conductive. Therefore, the outer can 10 is connected to the battery element 40 (negative electrode 42) via the negative lead 52, thus functioning as an external connection terminal for the negative electrode 42. This is because the secondary battery may not have an external connection terminal for the negative electrode 42 separate from the outer can 10, thus preventing a reduction in the element's volume due to the presence of the external connection terminal for the negative electrode 42. As a result, the element's volume increases, and therefore the energy density per unit volume of the secondary battery increases.

[0065] Specifically, the outer can 10 (containing the storage section 11 and the lid 12) comprises one or more conductive materials, such as metals and alloys, including iron, copper, nickel, stainless steel, ferroalloys, copper alloys, and nickel alloys. The type of stainless steel is not particularly limited, but specifically, it may be SUS304 or SUS316. Furthermore, the materials used to form the storage section 11 and the lid 12 may be the same or different from each other.

[0066] It should be noted that, as described later, the outer can 10 (lid 12) is insulated from the external terminal 20, which functions as the external connection terminal of the positive electrode 41, via a gasket 30. This is to prevent contact (short circuit) between the outer can 10 (the external connection terminal of the negative electrode 42) and the external terminal 20 (the external connection terminal of the positive electrode 41).

[0067] [External terminal]

[0068] like Figure 1 as well as Figure 2 As shown, the external terminal 20 is a connection terminal used to connect to the electronic device when the secondary battery is mounted on the electronic device. As described above, the external terminal 20 is mounted on the outer casing 10 (cover 12) and is therefore supported by the cover 12.

[0069] Here, since the external terminal 20 is connected to the battery element 40 (positive terminal 41) via the positive lead 51, it functions as an external connection terminal for the positive terminal 41. Therefore, when using the secondary battery, since the secondary battery is connected to the electronic device via the external terminal 20 (external connection terminal for the positive terminal 41) and the outer canister 10 (external connection terminal for the negative terminal 42), the electronic device can operate by using the secondary battery as a power source.

[0070] The external terminal 20 is a flat, generally plate-shaped component, disposed inside the recess 12H via a washer 30. Thus, the external terminal 20 is insulated from the cover 12 via the washer 30. Here, the external terminal 20 is housed inside the recess 12H in a manner that does not protrude upwards beyond the cover 12. This is because, compared to a case where the external terminal 20 protrudes upwards beyond the cover 12, the height H of the secondary battery is reduced, thereby increasing the energy density per unit volume of the secondary battery.

[0071] It should be noted that since the outer diameter of the outer terminal 20 is smaller than the inner diameter of the recess 12H, the outer terminal 20 is isolated from the cover 12 around it. Therefore, the gasket 30 is only disposed in a part of the area between the outer terminal 20 and the cover 12 (recess 12H), and more specifically, only in the part where the outer terminal 20 and the cover 12 can contact each other if the gasket 30 is not present.

[0072] Furthermore, the external terminal 20 comprises one or more conductive materials, such as metallic materials and alloy materials, including aluminum and aluminum alloys. Alternatively, the external terminal 20 may be formed of a cladding material. This cladding material comprises, from the side closest to the washer 30, an aluminum layer and a nickel layer, wherein the aluminum layer and the nickel layer are rolled together.

[0073] [washer]

[0074] like Figure 2 As shown, the gasket 30 is an insulating component disposed between the outer can 10 (cap 12) and the external terminal 20, which is fixed to the cap 12 via the gasket 30. The gasket 30 has an annular planar shape with a through hole at a location corresponding to the through hole 12K. Furthermore, the gasket 30 contains one or more insulating materials, such as polypropylene and polyethylene, which are insulating polymers.

[0075] The placement range of the washer 30 is not particularly limited, so it can be set arbitrarily. Here, the washer 30 is disposed inside the recess 12H in the gap between the upper surface of the cover 12 and the lower surface of the external terminal 20.

[0076] [Battery Components]

[0077] like Figure 2 as well as Figure 3 As shown, battery element 40 is a power generation element that performs charge and discharge reactions and is housed inside the outer casing 10. Battery element 40 includes a positive electrode 41 and a negative electrode 42. Here, battery element 40 also includes a separator 43 and an electrolyte (not shown) in liquid form.

[0078] Figure 2 The center line PC shown is a line segment along the outer diameter D of the secondary battery (outer canister 10) that corresponds to the center of the battery element 40. That is, the position of the center line PC corresponds to the position of the center of the battery element 40.

[0079] The battery element 40 is a so-called wound electrode body. That is, in the battery element 40, the positive electrode 41 and the negative electrode 42 are stacked on top of each other via a separator 43, and the positive electrode 41, the negative electrode 42 and the separator 43 are wound together. As a result, since the positive electrode 41 and the negative electrode 42 are wound together opposite each other via the separator 43, a wound center space 40K is formed at the center of the battery element 40.

[0080] Here, the positive electrode 41, the negative electrode 42, and the separator 43 are wound such that the separator 43 is respectively arranged on the outermost and innermost periphery. The number of turns of each of the positive electrode 41, the negative electrode 42, and the separator 43 is not particularly limited, and can therefore be set arbitrarily.

[0081] The battery element 40 has the same three-dimensional shape as the outer can 10, and therefore has a flat and cylindrical three-dimensional shape. This is because, compared to the case where the battery element 40 has a different three-dimensional shape from the outer can 10, it is difficult to create a so-called dead zone (the gap between the outer can 10 and the battery element 40) when the battery element 40 is housed inside the outer can 10, thus the internal space of the outer can 10 can be utilized effectively. As a result, the element space volume increases, and therefore the energy density per unit volume of the secondary battery increases.

[0082] (positive electrode)

[0083] Positive electrode 41 is the first electrode used for the charge-discharge reaction, and as... Figure 3 As shown, it includes a positive current collector 41A and a positive active material layer 41B.

[0084] The positive current collector 41A has one side with a positive active material layer 41B disposed thereon. The positive current collector 41A contains a conductive material such as a metal, which is aluminum, etc.

[0085] The positive electrode active material layer 41B is disposed on both sides of the positive electrode current collector 41A, and includes any one or more positive electrode active materials capable of lithium intercalation and deintercalation. Alternatively, the positive electrode active material layer 41B may be disposed on only one side of the positive electrode current collector 41A. Furthermore, the positive electrode active material layer 41B may also include 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; specifically, it may be a coating method, etc.

[0086] The positive electrode active material contains lithium compounds. Lithium compounds are a general term for compounds containing lithium as a constituent element; more specifically, they are compounds containing lithium and one or more transition metal elements as constituent elements. This is because high energy density can be achieved. In addition, lithium compounds may also contain one or more other elements (excluding lithium and transition metal elements). The types of lithium compounds are not particularly limited; specifically, they include 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.

[0087] The positive electrode binder contains one or more of synthetic rubber and polymer compounds. The synthetic rubber is styrene-butadiene rubber, and the polymer compound is polyvinylidene fluoride, etc. The positive electrode conductive agent contains one or more of conductive materials, such as graphite, carbon black, acetylene black, and Ketjen black. Alternatively, the conductive material can also be a metallic material or a polymer compound.

[0088] (negative electrode)

[0089] Negative electrode 42 is the second electrode used for the charge-discharge reaction, such as... Figure 3 As shown, it includes a negative current collector 42A and a negative active material layer 42B.

[0090] The negative current collector 42A has one side with a negative active material layer 42B disposed thereon. The negative current collector 42A contains a conductive material such as a metal, which is copper, etc.

[0091] The negative electrode active material layer 42B is disposed on both sides of the negative electrode current collector 42A, and contains any one or more negative electrode active materials capable of lithium intercalation and deintercalation. Alternatively, the negative electrode active material layer 42B may be disposed 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 each of the negative electrode binder and negative electrode conductive agent are the same as details regarding each of the positive electrode binder and positive electrode conductive agent. The method for forming the negative electrode active material layer 42B is not particularly limited; specifically, it may be any one or more of coating, vapor phase, liquid phase, spraying, and sintering methods.

[0092] The negative electrode active material contains one or both of carbon materials and metallic materials. This is because high energy density can be obtained. Carbon materials include easily graphitized carbon, difficult-to-graphitize carbon, and graphite (natural and artificial graphite). Metallic materials are materials containing one or more metallic elements and half-metallic elements capable of forming alloys with lithium as constituent elements. These metallic elements and half-metallic elements are one or both of silicon and tin. Furthermore, metallic materials can be monomers, alloys, compounds, mixtures of two or more of them, or materials containing two or more of their phases. Specific examples of metallic materials are TiSi2 and SiO. x (0 < x ≤ 2, or 0.2 < x < 1.4), etc.

[0093] Here, the height of the negative electrode 42 is greater than the height of the positive electrode 41. That is, the negative electrode 42 protrudes upwards more than the positive electrode 41 and downwards more than the positive electrode 41. This is to prevent the deposition of lithium that has been extracted from the positive electrode 41. This "height" is the dimension corresponding to the height H of the secondary battery described above, i.e. Figure 1 as well as Figure 2 The vertical dimension of each. The definition of height given here will also be used in the following descriptions.

[0094] (Septum)

[0095] like Figure 2 as well as Figure 3 As shown, the separator 43 is an insulating porous membrane disposed between the positive electrode 41 and the negative electrode 42, which prevents short circuits between the positive electrode 41 and the negative electrode 42 while allowing lithium ions to pass through. The separator 43 contains a polymer compound such as polyethylene.

[0096] Here, the height of the diaphragm 43 is greater than the height of the negative electrode 42. That is, the diaphragm 43 protrudes upwards and downwards more than the negative electrode 42. As will be described later, this is to use the diaphragm 43 to insulate the positive electrode lead 51 from the negative electrode 42.

[0097] (electrolyte)

[0098] An electrolyte permeates each of 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 compounds, carboxylic acid ester compounds, and lactone compounds. An electrolyte containing such non-aqueous solvents is called a non-aqueous electrolyte. The electrolyte salt contains one or more light metal salts such as lithium salts.

[0099] [Positive lead]

[0100] like Figure 2 As shown, the positive lead 51 is housed inside the outer casing 10 and is the connection wiring to the positive electrode 41 and each of the external terminals 20. Here, the secondary battery has one positive lead 51. However, although not specifically illustrated, the secondary battery may also have two or more positive leads 51.

[0101] The positive lead 51 is connected to the upper end of the positive electrode 41, and more specifically, to the upper end of the positive current collector 41A. Furthermore, the positive lead 51 is connected to the lower surface of the external terminal 20 via a through hole 12K provided on the cover 12. The connection method of the positive lead 51 is not particularly limited, but specifically, it can be any one or more of the following welding methods: resistance welding and laser welding. Details regarding the welding methods described herein will also be provided later.

[0102] A portion of the positive lead 51 is insulated from each of the outer can 10 (cap 12) and the battery element 40 (negative electrode 42), and is held by the cap 12 and the battery element 40. That is, the portion of the positive lead 51 located between the external terminal 20 and the positive electrode 41 is substantially (indirectly) adjacent to each of the cap 12 and the battery element 40, and is therefore held by the cap 12 and the battery element 40 from above and below.

[0103] Thus, a portion of the positive electrode lead 51 is held by the cover 12 and the battery element 40 through each extension along the lower surface of the cover 12 and the upper surface of the battery element 40, and is therefore fixed inside the outer casing 10. This is because even if the secondary battery is subjected to external forces such as vibration and impact, the positive electrode lead 51 is difficult to move, and therefore the positive electrode lead 51 is difficult to break. Breakage of the positive electrode lead 51 refers to cracks appearing on the positive electrode lead 51, the positive electrode lead 51 being cut off, or the positive electrode lead 51 detaching from the positive electrode 41.

[0104] That is, "a portion of the positive lead 51 is held by the outer can 10 and the battery element 40" means that since the positive lead 51 is insulated from each of the outer can 10 and the battery element 40, and the positive lead 51 is held from above and below by the outer can 10 and the battery element 40, the positive lead 51 is difficult to move inside the outer can 10 even if the secondary battery is subjected to external forces such as vibration and impact.

[0105] It should be noted that the positive electrode lead 51 is preferably engaged with the battery element 40 by being pushed by the battery element 40. More specifically, as described above, the height of the separator 43 is greater than the height of each of the positive electrode 41 and the negative electrode 42, therefore the positive electrode lead 51 is preferably engaged with the upper end of the separator 43. In this case, a recess is formed at the upper end of the separator 43 due to the pushing of the positive electrode lead 51, and part or all of the positive electrode lead 51 is housed inside the recess, thus the positive electrode lead 51 is held by the separator 43. This is because the positive electrode lead 51 is more difficult to move inside the outer packaging can 10, and therefore less likely to break.

[0106] Here, as described above, since the cover 12 includes a protrusion 12P, a portion of the positive electrode lead 51 is held by the protrusion 12P and the battery element 40. That is, a portion of the positive electrode lead 51 extends along each of the lower surface of the protrusion 12P and the upper surface of the battery element 40, thereby being held by the protrusion 12P and the battery element 40. This is because the positive electrode lead 51 is more easily held by the protrusion 12P, and therefore less likely to be damaged.

[0107] In addition, a portion of the positive lead 51 is insulated from the cover portion 12 and the negative lead 42 via the diaphragm 43, the sealant 61, and each of the insulating films 62 and 63.

[0108] Specifically, as described above, the height of the diaphragm 43 is greater than the height of the negative electrode 42. Therefore, a portion of the positive electrode lead 51 is isolated from the negative electrode 42 via the diaphragm 43, thus providing insulation between them. This is to prevent a short circuit between the positive electrode lead 51 and the negative electrode 42.

[0109] Furthermore, the positive lead 51 is surrounded by an insulating sealant 61. Thus, a portion of the positive lead 51 is insulated from both the cover 12 and the negative lead 42 via the sealant 61. This prevents short circuits between the positive lead 51 and the cover 12, and also prevents short circuits between the positive lead 51 and the negative lead 42.

[0110] Furthermore, an insulating film 62 is disposed between the cover 12 and the positive lead 51. Thus, a portion of the positive lead 51 is insulated from the cover 12 via the insulating film 62. This prevents a short circuit between the positive lead 51 and the cover 12.

[0111] Furthermore, an insulating film 63 is disposed between the battery element 40 and the positive lead 51. Thus, a portion of the positive lead 51 is insulated from the negative electrode 42 via the insulating film 63. This is to prevent a short circuit between the positive lead 51 and the negative electrode 42.

[0112] The details regarding the forming material of the positive electrode lead 51 are the same as those regarding the forming material of the positive electrode current collector 41A. Furthermore, the forming materials of the positive electrode lead 51 and the positive electrode current collector 41A may be the same or different from each other.

[0113] Here, the positive lead 51 is closer to the front side than the center line PC. Figure 2 The positive lead 51 (on the right side of the center line PC) is connected to the positive terminal 41. Thus, a portion of the positive lead 51 is held by the cover 12 and the battery element 40 closer to the front side than the center line PC, and extends towards the external terminal 20. It should be noted that, in order to connect to the external terminal 20, the positive lead 51 is bent upwards into a crank shape on its way to the external terminal 20.

[0114] Here, from Figure 2 It can be seen that "closer to the front side than the center line PC" means that when the battery element 40 is divided into two regions along the outer diameter D with the center line PC as the reference, there is a region where the positive lead 51 is connected to the positive electrode 41. Figure 2 The area to the right of the center line PC). In contrast, from Figure 2It can be seen that "inner side than the center line PC" mentioned later refers to another area among the two regions mentioned above. Figure 2 (The area to the left of the center line PC). That is, the area further inside the center line PC refers to the area where, when the battery element 40 is divided into two regions along the outer diameter D with the center line PC as the reference, there is no connection between the positive lead 51 and the positive electrode 41.

[0115] The connection position of the positive lead 51 relative to the positive electrode 41 is not particularly limited, and can therefore be arbitrarily set. Preferably, the positive lead 51 is connected to the positive electrode 41 at a position closer to the inner circumference than the outermost circumference. This is because, unlike the case where the positive lead 51 is connected to the positive electrode 41 at its outermost circumference, corrosion of the outer can 10 due to electrolyte creep can be prevented. "Electrolyte creep" refers to the phenomenon where, when the positive lead 51 is positioned close to the inner wall of the outer can 10, the electrolyte in the battery element 40 creeps along the positive lead 51 and reaches the inner wall of the outer can 10, causing the outer can 10 to dissolve or change color due to contact with the electrolyte.

[0116] Here, the positive lead 51 is folded more than once between the positive electrode 41 and the external terminal 20. There is no particular limit to the number of times the positive lead 51 is folded, as long as it is folded more than once. "Folding back the positive lead 51" means that the positive lead 51 is bent at an angle greater than 90° during the process.

[0117] Specifically, the positive lead 51 is folded back only once near the external terminal 20. This is because, since the folded-back portion of the positive lead 51 is the remaining portion, a length margin for the positive lead 51 can be obtained.

[0118] Therefore, as will be described later, when the outer can 10 is formed using the housing 11 and the cover 12 in the manufacturing process of the secondary battery, the cover 12 can be erected relative to the housing 11 (see reference). Figure 5 Furthermore, when the secondary battery is subjected to external forces such as vibration and impact, the length margin of the positive electrode lead 51 is used to mitigate the external force, thus making the positive electrode lead 51 difficult to break. In addition, by utilizing the length margin of the positive electrode lead 51, the connection position of the positive electrode lead 51 relative to the positive electrode 41 can be arbitrarily changed without changing the length of the positive electrode lead 51.

[0119] In this case, the length of the positive lead 51 (including the total length with any allowance) is not particularly limited and can therefore be set arbitrarily. Preferably, the length of the positive lead 51 is more than half the outer diameter D of the outer can 10. This is because, regarding the length of the positive lead 51, sufficient length allowance can be ensured for the cover 12 to be erected relative to the storage section 11, making it easy to erect the cover 12 relative to the storage section 11.

[0120] The connection range of the positive lead 51 relative to the external terminal 20 is not particularly limited. Preferably, the connection range of the positive lead 51 relative to the external terminal 20 is sufficiently wide to make it difficult for the positive lead 51 to detach from the external terminal 20, and sufficiently narrow to allow for a length margin in the positive lead 51. Preferably, the connection range of the positive lead 51 relative to the external terminal 20 is sufficiently narrow because the portion of the positive lead 51 not connected to the external terminal 20 constitutes a length margin, and therefore this length margin is sufficiently large.

[0121] It should be noted that since the positive lead 51 is physically separated from the positive current collector 41A, it is therefore separate from the positive current collector 41A. However, since the positive lead 51 is physically continuous with the positive current collector 41A, it can be integrated with the positive current collector 41A.

[0122] [Negative lead]

[0123] like Figure 2 As shown, the negative electrode lead 52 is housed inside the outer can 10 and connects to the negative electrode 42 and each of the outer can 10 (housing section 11). Here, the secondary battery has one negative electrode lead 52. Alternatively, although not specifically illustrated, the secondary battery may have two or more negative electrode leads 52.

[0124] The negative lead 52 is connected to the lower end of the negative electrode 42, and more specifically, to the lower end of the negative current collector 42A. Additionally, the negative lead 52 is connected to the bottom surface of the receiving portion 11. The details of the method for connecting the negative lead 52 are the same as those for connecting the positive lead 51.

[0125] The details regarding the forming material of the negative electrode lead 52 are the same as those regarding the forming material of the negative electrode current collector 42A. Furthermore, the forming materials of the negative electrode lead 52 and the negative electrode current collector 42A may be the same or different from each other.

[0126] The connection position of the negative lead 52 relative to the negative electrode 42 is not particularly limited, and can therefore be set arbitrarily. Here, the negative lead 52 is connected to the negative electrode 42 at the outermost periphery of the negative electrode 42.

[0127] It should be noted that since the negative lead 52 is physically separated from the negative current collector 42A, it is therefore separate from the negative current collector 42A. However, since the negative lead 52 is physically continuous with the negative current collector 42A, it can be integrated with the negative current collector 42A.

[0128] [Sealant]

[0129] like Figure 2 As shown, sealant 61 is a first insulating component covering the periphery of the positive lead 51, and has a tubular structure. Here, in order to enable the positive lead 51 to connect with the positive electrode 41 and each of the external terminals 20, sealant 61 covers the periphery of the middle portion of the positive lead 51.

[0130] The sealant 61 contains one or more insulating materials, such as insulating polymer compounds, and the insulating material is polyimide, etc.

[0131] [Insulating film]

[0132] like Figure 2 As shown, the insulating film 62 is a second insulating component disposed between the cover portion 12 and the positive lead 51. Here, the insulating film 62 has an annular planar shape with through holes at the locations corresponding to the through holes 12K.

[0133] Here, since the insulating film 62 has an adhesive layer (not shown) on one side, it can be bonded to either the cover portion 12 or the positive lead 51 via this adhesive layer. Furthermore, since the insulating film 62 has adhesive layers (not shown) on both sides, it can be bonded to both the cover portion 12 and the positive lead 51 via these adhesive layers.

[0134] In addition, the insulating film 62 contains one or more insulating materials such as insulating polymer compounds, and the insulating material is polyimide, etc.

[0135] like Figure 2 As shown, the insulating film 63 is a third insulating component disposed between the battery element 40 and the positive electrode lead 51. Here, the insulating film 63 has a flat planar shape. The insulating film 63 is configured to shield the winding center space 40K and cover the battery element 40 around the winding center space 40K.

[0136] The details regarding the forming material of insulating film 63 are the same as those regarding the forming material of insulating film 62. Furthermore, the forming materials of insulating film 63 and insulating film 62 may be the same or different from each other.

[0137] [other]

[0138] It should be noted that a secondary battery may also have one or more of the other components not shown in the figure.

[0139] Specifically, the secondary battery includes a safety valve mechanism. When the internal pressure of the outer can 10 reaches a certain value, the safety valve mechanism cuts off the electrical connection between the outer can 10 and the battery element 40 (negative terminal 42). The reason the internal pressure of the outer can 10 reaches a certain value is due to a short circuit inside the secondary battery, external heating of the secondary battery, etc. The location of the safety valve mechanism is not particularly limited, but it is preferably located at either the bottom M1 or M2, and more preferably at the bottom M2 where the external terminal 20 is not installed.

[0140] Furthermore, the secondary battery has an insulator between the outer canister 10 and the battery element 40. This insulator includes one or more of the following: insulating film and insulating sheet, to prevent short circuits between the outer canister 10 and the battery element 40 (positive electrode 41). The range of insulator placement is not particularly limited, and therefore can be arbitrarily set.

[0141] It should be noted that an open valve is provided on the outer packaging tank 10. This open valve ruptures when the internal pressure of the outer packaging tank 10 reaches a certain value, thereby releasing its internal pressure. The location of the open valve is not particularly limited, but similar to the location of the safety valve mechanism described above, either the bottom M1 or M2 is preferred, and the bottom M2 is more preferred.

[0142] <1-2 Actions>

[0143] When the secondary battery is charged, lithium is deintercalated from the positive electrode 41 in the battery element 40 and intercalated into the negative electrode 42 via the electrolyte. Conversely, when the secondary battery is discharged, lithium is deintercalated from the negative electrode 42 in the battery element 40 and intercalated into the positive electrode 41 via the electrolyte. During these charging and discharging processes, lithium is intercalated and deintercalated in an ionic state.

[0144] <1-3. Manufacturing Method>

[0145] Figure 4 This describes the three-dimensional structure of the outer can 10 used in the manufacturing process of a secondary battery, and... Figure 1 correspond. Figure 5 The cross-sectional structure of the outer can 10 is shown to illustrate the manufacturing process of the secondary battery. Figure 2 correspond.

[0146] In addition, Figure 4 In the image, since the cover 12 is being welded to the storage section 11 before this process, the image shows the cover 12 separated from the storage section 11. Figure 5Since this was done before the cover 12 was welded onto the storage section 11, the cover 12 is shown standing upright relative to the storage section 11.

[0147] Please refer to the following instructions at any time. Figure 4 as well as Figure 5 , and as already explained Figures 1 to 3 .

[0148] Here, in order to form the outer packaging can 10, such as Figure 4 As shown, a storage section 11 and a cover section 12 are physically separated from each other. The storage section 11 is a generally container-shaped component with the bottom M2 and the side wall section M3 integrated together, and has an opening 11K. The cover section 12 is a generally plate-shaped component corresponding to the bottom M1, and an external terminal 20 is pre-installed in the recess 12H of the cover section 12 via a washer 30.

[0149] In addition, since the bottom M2 and the side wall M3 are separate from each other, the storage part 11 can also be prepared by welding the side wall M3 onto the bottom M2.

[0150] [The production of the positive electrode]

[0151] First, a positive electrode mixture is prepared by mixing positive electrode active material, positive electrode binder, and positive electrode conductive agent. Then, the positive electrode mixture is added to an organic solvent to prepare a paste-like positive electrode mixture slurry. Next, the positive electrode mixture slurry is coated onto 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 roller press or similar device. In this process, the positive electrode active material layer 41B can be heated, and the compression molding process can be repeated multiple times. Thus, the positive electrode 41 is manufactured.

[0152] [Making the negative electrode]

[0153] The negative electrode 42 is manufactured using the same steps as those used to manufacture the positive electrode 41. Specifically, after preparing a paste-like negative electrode slurry containing an organic solvent and a negative electrode binder (such as a negative electrode active material, a negative electrode binder, and a negative electrode conductive agent), the negative electrode slurry is coated onto both sides of the negative electrode current collector 42A to form a negative electrode active material layer 42B. Subsequently, the negative electrode active material layer 42B is compressed and molded using a roller press or similar device. Thus, the negative electrode 42 is manufactured.

[0154] [Preparation of Electrolyte]

[0155] An electrolyte salt is added to a solvent. The electrolyte salt is then dispersed or dissolved in the solvent, thus preparing an electrolyte solution.

[0156] [Assembly of a secondary battery]

[0157] First, using a welding method such as resistance welding, the positive lead 51, which is covered by sealant 61 around it, is connected to the positive electrode 41 (positive current collector 41A), and the negative lead 52 is connected to the negative electrode 42 (negative current collector 42A).

[0158] Next, the positive electrode 41 connected to the positive electrode lead 51 and the negative electrode 42 connected to the negative electrode lead 52 are stacked on top of each other via the diaphragm 43, and then the positive electrode 41, the negative electrode 42 and the diaphragm 43 are wound together, thereby... Figure 4 As shown, a wound body 40Z is fabricated. This wound body 40Z has the same structure as the battery element 40, except that none of the positive electrode 41, negative electrode 42, and separator 43 are impregnated with electrolyte. It should be noted that... Figure 4 The illustrations of each of the positive lead 51 and the negative lead 52 are omitted in the text.

[0159] Next, the wound body 40Z, to which each of the positive lead 51 and the negative lead 52 is connected, is housed inside the housing portion 11 from the opening 11K. In this case, the negative lead 52 is connected to the housing portion 11 using a welding method such as resistance welding. Next, an insulating film 63 is placed on the wound body 40Z.

[0160] Next, prepare a cover 12 with an external terminal 20 pre-installed via a washer 30 and an insulating film 62 pre-installed. Then, use a welding method such as resistance welding to connect the positive lead 51 to the external terminal 20 via the through hole 12K.

[0161] Thus, the wound body 40Z (positive electrode 41) housed inside the storage section 11 and the external terminal 20 mounted on the cover section 12 are interconnected via the positive electrode lead 51. Therefore, as Figure 5 As shown, with the winding body 40Z and the external terminal 20 connected to each other via the positive lead 51, the cover 12 can be raised relative to the storage part 11.

[0162] from Figure 5 It is understood that "the cover 12 is raised relative to the storage portion 11" means that, in order to prevent the cover 12 from obstructing the opening 11K, the cover 12 is arranged in a manner approximately orthogonal to the bottom surface of the storage portion 11 while the battery element 40 and the external terminal 20 are connected to each other via the positive lead 51. In this case, by sufficiently increasing the length of the positive lead 51, even when the cover 12 is raised relative to the storage portion 11, it is possible to prevent the positive lead 51 from being excessively stretched and cut.

[0163] Next, electrolyte is injected into the interior of the housing 11 through the opening 11K. In this case, as described above, even if the battery element 40 and the external terminal 20 are connected to each other via the positive lead 51, the cover 12 will not obstruct the opening 11K, so the electrolyte can be easily injected into the interior of the housing 11 through the opening 11K. As a result, the electrolyte permeates the winding body 40Z (positive electrode 41, negative electrode 42, and separator 43), thereby creating the battery element 40 as a winding electrode body.

[0164] Next, by tilting the cover 12 close to the storage portion 11, and using the cover 12 to cover the opening 11K, the cover 12 is welded to the storage portion 11 using a welding method such as laser welding. In this case, as... Figure 2 As shown, a portion of the positive lead 51 (sealant 61) is held between the cover 12 (insulating film 62) and the battery element 40 (insulating film 63), and the positive lead 51 is folded back before the connection point relative to the external terminal 20. Thus, an outer can 10 is formed, and the battery element 40 and the like are housed inside the outer can 10, thereby assembling a secondary battery.

[0165] Stabilization of secondary batteries

[0166] 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 arbitrarily set. This forms a coating on the surface of the negative electrode 42, thereby stabilizing the electrochemical state of the secondary battery. Thus, the secondary battery is completed.

[0167] <1-4. Functions and Effects>

[0168] According to the secondary battery, the battery element 40, including a positive electrode 41 and a negative electrode 42, is housed inside the outer can 10, is insulated from the outer can 10, and has an external terminal 20 mounted on the outer can 10. A positive lead 51 is connected to each of the positive electrode 41 and the external terminal 20. A portion of the positive lead 51 is insulated from each of the outer can 10 and the negative electrode 42 and is held by the outer can 10 and the battery element 40.

[0169] In this case, as described above, a portion of the positive lead 51 is insulated from and held by the outer can 10 and the battery element 40. Therefore, since the positive lead 51 is fixed inside the outer can 10, it is difficult for the positive lead 51 to move even if the secondary battery is subjected to external forces such as vibration and impact. Thus, the positive lead 51 is difficult to break due to external forces, thereby achieving excellent physical durability.

[0170] In particular, the above-mentioned advantages (functions and effects) can be obtained in the secondary battery of this embodiment for the reasons explained below.

[0171] from Figure 1 as well as Figure 2 As can be seen, the secondary battery of this embodiment, referred to as coin-type and button-type, etc., is a secondary battery with a flat and cylindrical three-dimensional shape, and has a small external terminal 20 that functions as an external connection terminal for the positive electrode 41. In this case, since the size of the external terminal 20 is small, the connection area of ​​the positive electrode lead 51 relative to the external terminal 20 becomes small. Therefore, in order to maintain the electrical connection between the external terminal 20 and the positive electrode lead 51, it is necessary to sufficiently fix the positive electrode lead 51 inside the outer casing 10.

[0172] From this perspective, in the secondary battery of this embodiment, since the positive lead 51 is connected to the small external terminal 20, even though the connection area of ​​the positive lead 51 relative to the external terminal 20 is small, the positive lead 51 is sufficiently fixed inside the outer casing 10, making it difficult for it to be damaged by external forces. Therefore, even if the secondary battery is subjected to external forces, it is easy to maintain the electrical connection between the external terminal 20 and the positive lead 51, thus achieving the advantage of improved physical durability.

[0173] Furthermore, in the secondary battery of this embodiment, which has a small external terminal 20 as an external connection terminal serving as the positive electrode 41, from Figure 2 As can be seen, the outer can 10 (cover 12), which functions as the external connection terminal for the negative electrode 42, is located near the external terminal 20. In this case, the two external connection terminals (cover 12 and external terminal 20) with different polarities are close to each other. Therefore, in order to prevent a short circuit between the cover 12 and the external terminal 20, and to ensure that the positive lead 51 is sufficiently far away from the cover 12, the connection area of ​​the positive lead 51 relative to the external terminal 20 needs to be sufficiently small.

[0174] From this perspective, in the secondary battery of this embodiment, even though the connection area of ​​the positive lead 51 relative to the external terminal 20 is small, the positive lead 51 is sufficiently fixed inside the outer casing 10, making it difficult for it to be damaged by external forces. Therefore, as described above, even if the secondary battery is subjected to external forces, it is easy to maintain the electrical connection between the external terminal 20 and the positive lead 51, thus achieving the advantage of improved physical durability.

[0175] In particular, in the secondary battery of this embodiment, if the positive electrode lead 51 is connected to the positive electrode 41 closer to the center line PC, and a portion of the positive electrode lead 51 is clamped by the outer casing 10 and the battery element 40 closer to the center line PC, then the positive electrode lead 51 is sufficiently fixed inside the outer casing 10. Therefore, the positive electrode lead 51 is less likely to break, thereby achieving a higher efficiency.

[0176] Furthermore, if the outer can 10 includes a protrusion 12P, and a portion of the positive lead 51 is held by the protrusion 12P and the battery element 40, then the protrusion 12P makes it easier to hold the positive lead 51. Therefore, since the positive lead 51 is less likely to break, a higher efficiency can be achieved.

[0177] In this case, if the outer can 10 includes a recess 12H formed by the protrusion 12P, and the external terminal 20 is housed inside the recess 12H, the height H of the secondary battery becomes smaller. Therefore, since the energy density per unit volume of the secondary battery increases, a higher efficiency can be obtained.

[0178] In addition, if the height of the insulating diaphragm 43 is greater than the height of the negative electrode 42, and a portion of the positive electrode lead 51 is insulated from the negative electrode 42 via the diaphragm 43, a short circuit between the positive electrode lead 51 and the negative electrode 42 can be prevented, thus achieving a higher efficiency.

[0179] In this case, if the positive electrode 41 and the negative electrode 42 are wound opposite to each other via the diaphragm 43, and the positive electrode lead 51 is connected to the positive electrode 41 at a position closer to the inner circumference than the outermost circumference of the positive electrode 41, corrosion of the outer can 10 due to electrolyte creep can be prevented, thus achieving a higher effect.

[0180] Furthermore, if the sealant 61 covers the area around the positive lead 51, and a portion of the positive lead 51 is insulated from the outer can 10 and each of the negative electrode 42 via the sealant 61, then short circuits between the positive lead 51 and the outer can 10 and between the positive lead 51 and the negative electrode 42 can be prevented, thus achieving a higher effect.

[0181] In this case, particularly if the positive lead 51 is surrounded by sealant 61, a clamping force is generated between the outer can 10 and the sealant 61, and also between the battery element 40 and the sealant 61, when the positive lead 51 is clamped by the outer can 10 and the battery element 40 via the sealant 61. Thus, the positive lead 51 is easily held by the outer can 10 and the battery element 40 using the clamping force supplied to the positive lead 51 via the sealant 61. Therefore, not only is the positive lead 51 insulated from the outer can 10 and the negative electrode 42 via the sealant 61, but the sealant 61 also makes it easier to fix the positive lead 51 inside the outer can 10, resulting in a higher efficiency.

[0182] In addition, if the insulating film 62 is disposed between the outer can 10 and the positive lead 51, and a portion of the positive lead 51 is insulated from the outer can 10 via the insulating film 62, a short circuit between the positive lead 51 and the outer can 10 can be prevented, thus achieving a higher efficiency.

[0183] In addition, if the insulating film 63 is disposed between the battery element 40 and the positive lead 51, and a portion of the positive lead 51 is insulated from the negative lead 42 via the insulating film 63, a short circuit between the positive lead 51 and the negative lead 42 can be prevented, thereby achieving a higher efficiency.

[0184] Furthermore, if the outer can 10 includes a receiving portion 11 and a cover portion 12 welded together, and the positive electrode lead 51 is folded back more than once, then the length allowance of the positive electrode lead 51 can be obtained. Therefore, in the manufacturing process of the secondary battery (the forming process of the outer can 10), the cover portion 12 can be erected relative to the receiving portion 11, and even if the secondary battery is subjected to external force, the positive electrode lead 51 is less likely to be damaged. The connection position of the positive electrode lead 51 relative to the positive electrode 41 can be arbitrarily changed, thus achieving a higher efficiency.

[0185] In this case, if the length of the positive lead 51 is more than half of the outer diameter D of the outer can 10, the cover 12 can be easily erected relative to the storage part 11 during the manufacturing process of the secondary battery, thus achieving a higher efficiency.

[0186] Furthermore, if the secondary battery is flat and cylindrical, such as a coin-shaped or button-shaped secondary battery, the positive lead 51 is less likely to break even in small secondary batteries that are relatively small in terms of size, thus achieving a higher efficiency.

[0187] In addition, if the secondary battery is a lithium-ion secondary battery, sufficient battery capacity can be stably obtained by utilizing the insertion and extraction of lithium, thus achieving higher performance.

[0188] <2. Variations>

[0189] As explained below, the structure of the secondary battery described above can be modified appropriately. Furthermore, any two or more of the variations described below can be combined with each other.

[0190] [Variation Example 1]

[0191] exist Figure 2 In the present invention, the secondary battery includes all of the sealant 61 and the insulating films 62 and 63. However, although not specifically illustrated here, the secondary battery may not include all of the sealant 61 and the insulating films 62 and 63, provided that the positive lead 51 is insulated from the outer can 10 and each of the negative electrode 42.

[0192] Specifically, firstly, if the positive lead 51 is insulated from the negative electrode 42 via the separator 43, the secondary battery may not have an insulating film 63. Secondly, if the positive lead 51 is insulated from both the outer can 10 and the negative electrode 42 via the sealant 61, the secondary battery may not have one or both of the insulating films 62 and 63. Thirdly, if the positive lead 51 is insulated from both the outer can 10 and the negative electrode 42 via the separator 43 and the insulating film 62, the secondary battery may not have one or both of the sealant 61 and the insulating film 63.

[0193] In these cases, the same effect can be achieved because the positive lead 51 is insulated from each of the outer can 10 and the negative lead 42.

[0194] [Variation Example 2]

[0195] exist Figure 2 In the first case, since the height of the diaphragm 43 is greater than the height of the negative electrode 42, the positive electrode lead 51 is insulated from the negative electrode 42 via the diaphragm 43. However, if the positive electrode lead 51 is insulated from the negative electrode 42 via the insulating film 63 by expanding the installation range of the insulating film 63, since the height of the diaphragm 43 is not greater than the height of the negative electrode 42, the positive electrode lead 51 may not be insulated from the negative electrode 42 via the diaphragm 43.

[0196] In this case, since the positive electrode lead 51 is insulated from the negative electrode 42 via the insulating film 63, the same effect can be obtained. In addition, in order to prevent the deposition of lithium extracted from the positive electrode 41, it is preferable that the height of the separator 43 is greater than the height of the negative electrode 42.

[0197] [Variation Example 3]

[0198] exist Figure 2 In this case, the insulating film 62 only covers the lower surface of the cover portion 12 (protrusion 12P). However, the area where the insulating film 62 is installed is not particularly limited as long as a portion of the positive lead 51 is insulated from the outer can 10 via the insulating film 62.

[0199] Specifically, such as with Figure 2 corresponding Figure 6 As shown, the insulating film 62 not only covers the lower surface of the cover 12, but also extends to the side surface of the cover 12 (the inner wall surface of the cover 12 in the through hole 12K). In this case, the portion of the positive lead 51 exposed without being covered by the sealant 61 becomes difficult to contact with the cover 12. Therefore, short circuits between the positive lead 51 and the outer can 10 can be further prevented, resulting in a higher efficiency.

[0200] [Variation Example 4]

[0201] exist Figure 2In this configuration, a portion of the positive lead 51 is held by the outer can 10 and the battery element 40 closer to the front side than the center line PC, and the positive lead 51 is folded back just before being connected to the external terminal 20. However, the extent to which the positive lead 51 is held by the outer can 10 and the battery element 40 is not particularly limited, and the folded-back position of the positive lead 51 is not particularly limited.

[0202] Specifically, such as with Figure 2 corresponding Figure 7 As shown, the positive electrode lead 51 extends from the front side of the center line PC to the inner side of the center line PC, and therefore folds back on the inner side of the center line PC. A portion of the positive electrode lead 51 can also be held by the outer casing 10 and the battery element 40 on the inner side of the center line PC. In this case, the area where the insulating film 63 is disposed can also be expanded from the center line PC inwards. Here, the sealant 61 covers the area around the unfolded portion of the positive electrode lead 51.

[0203] In this case, the positive lead 51 is also held inside the center line PC, and the length margin of the positive lead 51 is increased. Therefore, since the positive lead 51 is more difficult to break, a higher efficiency can be obtained.

[0204] [Variation Example 5]

[0205] It should be noted that, in Figure 7 In the middle, the positive lead 51 extends further inside the center line PC to below the protrusion 12P, and then folds back below the protrusion 12P. However, as with Figure 7 corresponding Figure 8 As shown, the positive lead 51 can also extend further inward than the center line PC to a point beyond the protrusion 12P, and then fold back at the point beyond the protrusion 12P. The area where the insulating film 63 is disposed can also be further expanded inward than the center line PC. In this case, since the length margin of the positive lead 51 is further increased, a higher efficiency can be obtained.

[0206] [Variation Example 6]

[0207] The area covered by the sealant 61 on the positive lead 51 is not particularly limited, and therefore can be set arbitrarily. Specifically, as with... Figure 7 corresponding Figure 9 As shown, the sealant 61 covers not only the unfolded portion of the positive lead 51, but also the folded portion. That is, when the positive lead 51 is folded back, the sealant 61 covering the area around the positive lead 51 can also be folded back together.

[0208] In this case, since the sealant 61 is folded back, the outer can 10 (cap 12) is moved away from the positive lead 51. Therefore, in order to maintain the state in which the positive lead 51 is held between the outer can 10 and the battery element 40, a process can be implemented. Specifically, the extended portion of the positive lead 51 can be positioned between the outer can 10 and the battery element 40 before it extends to the point where it connects to the external terminal 20. Alternatively, the thickness of the insulating film 62 can be locally increased.

[0209] In this case, since the positive lead 51 is easily insulated from the outer can 10 and the negative lead 42 via the sealant 61, a higher effect can be obtained.

[0210] [Variation Example 7]

[0211] Of course, as with Figure 8 as well as Figure 9 corresponding Figure 10 As shown, when the positive lead 51 folds back at the point where it passes the protrusion 12P, the sealant 61 can also cover the folded-back portion of the positive lead 51.

[0212] In this case, even if the length of the positive lead 51 is increased to increase the length margin, the positive lead 51 can be easily insulated from the outer can 10 and the negative lead 42 by the sealant 61, thus achieving a higher effect.

[0213] [Variations 8 and 9]

[0214] exist Figure 2 In this configuration, the insulating film 63 is arranged to cover the battery element 40 surrounding the central space 40K. However, the extent of the insulating film 63 is not particularly limited, as long as the positive lead 51 is insulated from the negative electrode 42 via the insulating film 63.

[0215] Specifically, such as with Figure 2 corresponding Figure 11 As shown, the insulating film 63 may also have the same structure as the insulating film 62 (Modification 8). That is, the insulating film 63 may also have an annular planar shape with a through hole at the location corresponding to the through hole 12K.

[0216] Additionally, as with Figure 7 corresponding Figure 12 As shown, when the positive electrode lead 51 is folded back below the protrusion 12P, the insulating film 63 can be disposed only between the portion of the positive electrode lead 51 that is not covered by the sealant 61 and the battery element 40 (Modification 9).

[0217] In these cases, the exposed portion of the positive lead 51 not covered by the sealant 61 is unlikely to make contact with the negative electrode 42. Therefore, since short circuits between the positive lead 51 and the negative electrode 42 can be further prevented, a higher efficiency can be achieved.

[0218] [Variations 10-13]

[0219] It should be noted that any two or more of the variations 3 to 9 can also be combined with each other as described above.

[0220] Specifically, such as with Figure 7 as well as Figure 11 corresponding Figure 13 As shown, by combining variations 4 and 8, in the case where the positive lead 51 is folded back below the protrusion 12P and the area around the folded portion of the positive lead 51 is not covered by the sealant 61, an insulating film 63 with an annular planar shape can also be used (variation 10).

[0221] Additionally, as with Figure 7 as well as Figure 9 corresponding Figure 14 As shown, by combining variations 4 and 6, in which the positive lead 51 is folded back below the protrusion 12P, the front end portion of the positive lead 51 is extended, and the area around the folded portion of the positive lead 51 is covered by sealant 61, the insulating film 63 can also be omitted (variation 11).

[0222] Additionally, as with Figure 6 , Figure 7 as well as Figure 9 corresponding Figure 15 As shown, by combining variations 2, 4, and 6, and extending the front end of the positive lead 51 below the protrusion 12P, and covering the area around the folded portion of the positive lead 51 with sealant 61, the installation range of the gasket 30 can be expanded (variation 12).

[0223] Additionally, as with Figure 10 as well as Figure 14 corresponding Figure 16 As shown, by combining variations 7 and 11, where the positive lead 51 is folded back at the point where it passes the protrusion 12P, the front end portion of the positive lead 51 is extended, and the area around the folded portion of the positive lead 51 is covered by sealant 61, the insulating film 63 can also be omitted (variation 13).

[0224] [Variations 14-17]

[0225] exist Figure 2In this design, an outer can 10 is used, on the outside of a cover 12 having a protrusion 12P (or a recess 12H) and a flat external terminal 20 mounted thereon. However, the structure of the outer can 10 is not particularly limited and can be varied arbitrarily. It should be noted that the structures of the series of secondary batteries described below, except for the differences in the structures of the cover 12 and each of the external terminals 20, have similar characteristics to... Figure 2 The structure shown is the same as that of the secondary battery.

[0226] Specifically, such as with Figure 2 corresponding Figure 17 As shown, an outer can 10 with a flat external terminal 20 mounted on the inside of a flat cover 12 without a protrusion 12P can also be used. In this outer can 10, a flat external terminal 20 is mounted via a gasket 30 on the inside of the cover 12 having a through hole 12K, and the external terminal 20 is partially exposed in the through hole 12K. In this case, the placement of the insulating film 63 can be adjusted to suppress short circuits between the portion of the positive lead 51 not covered by the sealant 61 and the negative lead 42 (Modification 14).

[0227] Additionally, as with Figure 2 corresponding Figure 18 As shown, an outer can 10 with a flat external terminal 20 mounted on the outside of a flat cover 12 without a protrusion 12P can also be used. In this outer can 10, the external terminal 20 is mounted on the outside of the cover 12 with a through hole 12K via a gasket 30 (Modification 15).

[0228] Additionally, as with Figure 2 corresponding Figure 19 As shown, an outer can 10 can also be used, in which an external terminal 20, which is bent in a manner that partially protrudes outward from the center, is mounted on the inside of a flat cover 12 without a protrusion 12P. In this outer can 10, the external terminal 20 is mounted on the inside of the cover 12, which has a through hole 12K, via a gasket 30. In this case, the location of the insulating film 63 can be adjusted to suppress short circuits between the portion of the positive lead 51 not covered by the sealant 61 and the negative lead 42 (Modification 16).

[0229] In addition, such as with Figure 2 corresponding Figure 20 As shown, an outer can 10 (Modification 17) can also be used, in which an outer terminal 20 extending from the inside of the cover 12 through the through hole 12K provided in the cover 12 (recess 12H) is installed.

[0230] In the outer can 10, an external terminal 20 is inserted into the through hole 12K and is mounted on the cover 12 via a washer 30. The external terminal 20 includes a small outer diameter portion inserted into the through hole 12K and a pair of large outer diameter portions disposed on the inner and outer sides of the cover 12, each having an outer diameter larger than the inner diameter of the through hole 12K. Thus, the external terminal 20 will not detach from the cover 12 due to the difference in outer diameter between the small outer diameter portion and each of the pair of large outer diameter portions.

[0231] The large outer diameter portion of the external terminal 20, located inside the cover portion 12, is disposed inside the winding center space 40K. Thus, the positive lead 51 is connected to the external terminal 20 (large outer diameter portion) within its winding center space 40K.

[0232] In these cases, short circuits between the positive lead 51 and the outer can 10 can also be prevented, thus achieving the same effect.

[0233] [Variation Example 18]

[0234] exist Figure 2 In this configuration, the positive electrode 41 is connected to the external terminal 20 via the positive lead 51, and the negative electrode 42 is connected to the outer can 10 via the negative lead 52. Therefore, the external terminal 20 functions as an external connection terminal for the positive electrode 41, and the outer can 10 functions as an external connection terminal for the negative electrode 42.

[0235] However, although no specific illustration is provided here, it is also possible that the positive electrode 41 is connected to the outer container 10 via the positive electrode lead 51, and the negative electrode 42 is connected to the external terminal 20 via the negative electrode lead 52. Thus, the outer container 10 functions as an external connection terminal for the second electrode, i.e., the positive electrode 41, and the external terminal 20 functions as an external connection terminal for the first electrode, i.e., the negative electrode 42.

[0236] In this case, a portion of the negative lead 52 is insulated from each of the outer can 10 (cap 12) and the battery element 40 (positive electrode 41), and is held by the outer can 10 and the battery element 40. The external terminal 20, functioning as an external connection terminal for the negative electrode 42, contains one or more conductive materials selected from metallic and alloy materials, such as iron, copper, nickel, stainless steel, iron alloys, copper alloys, and nickel alloys. The outer can 10, functioning as an external connection terminal for the positive electrode 41, contains one or more conductive materials selected from metallic and alloy materials, such as aluminum, aluminum alloys, and stainless steel.

[0237] In this case, the secondary battery can also be connected to the electronic device via the external terminal 20 (the external connection terminal of the negative electrode 42) and the outer can 10 (the external connection terminal of the positive electrode 41), thus achieving the same effect.

[0238] Example

[0239] The embodiments of this technology are described below.

[0240] As described below, a secondary battery (lithium-ion secondary battery) was prepared, and its performance was then evaluated.

[0241] [Making a Second-hand Battery]

[0242] Here, it was made Figures 1 to 3 The secondary battery of Example 1 is shown. In this case, secondary batteries of Comparative Examples 1 and 2 were also made for comparison.

[0243] (Example 1)

[0244] By following the steps described below, a coin-shaped secondary battery in which the positive lead 51 is held between the outer can 10 and the battery element 40 is manufactured.

[0245] (The production of the positive electrode)

[0246] First, a positive electrode mixture was prepared by mixing 91 parts by mass of positive electrode active material (LiCoO2), 3 parts by mass of positive electrode binder (polyvinylidene fluoride), and 6 parts by mass of positive electrode conductive agent (graphite). Next, a paste-like positive electrode mixture slurry was prepared by adding the positive electrode mixture to an organic solvent (N-methyl-2-pyrrolidone) and stirring the solvent. Next, the positive electrode mixture slurry was coated onto both sides of a positive electrode current collector 41A (a strip of aluminum foil with a thickness of 12 μm) using a coating apparatus, and then dried to form a positive electrode active material layer 41B. Finally, the positive electrode active material layer 41B was compressed and molded using a roller press. Thus, a positive electrode 41 (width = 3.3 mm) was produced.

[0247] (Making the negative electrode)

[0248] First, a negative electrode mixture was prepared by mixing 95 parts by mass of negative electrode active material (graphite) and 5 parts by mass of negative electrode binder (polyvinylidene fluoride). Next, a paste-like negative electrode mixture slurry was prepared by adding the negative electrode mixture to an organic solvent (N-methyl-2-pyrrolidone) and stirring the solvent. Next, the negative electrode mixture slurry was coated onto both sides of the negative electrode current collector 42A (a strip of copper foil with a thickness of 15 μm) using a coating apparatus, and then dried to form the negative electrode active material layer 42B. Finally, the negative electrode active material layer 42B was compressed and molded using a roller press. Thus, the negative electrode 42 (width = 3.8 mm) was produced.

[0249] (Preparation of electrolyte)

[0250] An electrolyte salt (LiPF6) was added to a solvent (ethylene carbonate and diethyl carbonate), and the solvent was then stirred. In this case, the solvent mixing ratio (by weight) was ethylene carbonate:diethyl carbonate = 30:70, and the electrolyte salt concentration was 1 mol / kg relative to the solvent. Thus, the electrolyte salt dissolved or dispersed in the solvent, thereby preparing an electrolyte solution.

[0251] (Assembly of a secondary battery)

[0252] First, using resistance welding, an aluminum positive electrode lead 51 (thickness = 0.1 mm, width = 2.0 mm, and protruding length from positive electrode 41 = 11.7 mm) partially covered by a tubular sealant 61 (polypropylene film, outer diameter = 9.0 mm, inner diameter = 3.0 mm) is welded to the positive electrode 41 (positive current collector 41A). Next, using resistance welding, a nickel negative electrode lead 52 (thickness = 0.1 mm, width = 2.0 mm, and protruding length from negative electrode 42 = 6.0 mm) is welded to the negative electrode 42 (negative current collector 42A). In this case, the welding position of the positive electrode lead 51 is adjusted so that it is located within the winding path of the positive electrode 41.

[0253] Next, the positive electrode 41 and the negative electrode 42 are stacked together via a diaphragm 43 (a microporous polyethylene membrane with a thickness of 25 μm and a width of 4.0 mm), and then the positive electrode 41, the negative electrode 42 and the diaphragm 43 are wound together to produce a cylindrical wound body 40Z (outer diameter of 11.6 mm) with a winding center space 40K (inner diameter of 2.0 mm).

[0254] Next, an annular insulating film (polyimide film, outer diameter = 11.6 mm, inner diameter = 2.2 mm, thickness = 0.05 mm) for padding is placed inside the cylindrical receiving portion 11 (wall thickness = 0.15 mm, outer diameter = 12.0 mm, height = 5.0 mm) made of stainless steel (SUS316). Then, the wound body 40Z is placed inside the receiving portion 11. In this case, the negative lead 52 is soldered to the receiving portion 11 using resistance welding. Next, using resistance welding, the positive lead 51 is soldered to the external terminal 20 in a stainless steel (SUS316) disc-shaped cover 12 (wall thickness = 0.15 mm, outer diameter 11.7 mm). The cover 12 has a recess 12H (inner diameter = 9.0 mm, step height = 0.3 mm) with a through hole 12K (inner diameter = 3.0 mm). The aluminum disc-shaped external terminal 20 (wall thickness = 0.3 mm, outer diameter = 7.2 mm) is mounted via a washer 30 (polyimide film, outer diameter = 9.2 mm, inner diameter = 3.2 mm).

[0255] Next, with the cover 12 upright relative to the storage section 11, electrolyte is injected into the interior of the storage section 11 through the opening 11K. Thus, the wound body 40Z (positive electrode 41, negative electrode 42, and separator 43) is impregnated with the electrolyte, thereby fabricating the battery element 40.

[0256] Finally, the opening 11K is covered with the cover 12, and then the cover 12 is welded to the housing 11 using laser welding. In this case, an annular insulating film 62 (polyimide film, outer diameter = 9.2 mm, inner diameter = 3.2 mm) is disposed between the cover 12 and the positive electrode lead 51, and a disc-shaped insulating film 63 (polyimide film, outer diameter = 3.2 mm) is disposed between the battery element 40 and the positive electrode lead 51. Thus, the housing 11 and the cover 12 form the outer can 10, and the battery element 40 is sealed inside the outer can 10, thereby assembling a secondary battery (outer diameter = 12.0 mm, height = 5.0 mm).

[0257] (Stabilization of secondary batteries)

[0258] The assembled secondary battery was subjected to one charge-discharge cycle at room temperature (temperature = 23℃). During charging, a constant current of 0.1C was used until the voltage reached 4.2V, followed by constant voltage charging at that 4.2V until the current reached 0.05C. During discharging, a constant current of 0.1C was used until the voltage reached 3.0V. 0.1C is the current required to fully discharge the battery (theoretical capacity) in 10 hours, and 0.05C is the current required to fully discharge the battery in 20 hours.

[0259] Therefore, due to the coating formed on the surface of the negative electrode 42, the secondary battery is electrochemically stable. Thus, the secondary battery is completed.

[0260] (Comparative Example 1)

[0261] By following the steps described below, a cylindrical secondary battery with the positive electrode lead not held by the outer can or battery element was manufactured. This secondary battery has the same structure as the secondary battery disclosed in Patent Document 1 (Japanese Patent Application Publication No. 2013-097903).

[0262] The manufacturing steps of this cylindrical secondary battery (Comparative Example 1) are the same as those of the coin-shaped secondary battery (Example 1), except as described below. In this case, the width of the positive electrode is 1.6 mm, the width of the negative electrode is 2.1 mm, the width of the separator is 2.3 mm, the protruding length of the positive electrode lead is 15.0 mm, and insulating films 62 and 63 are not used. Furthermore, after the battery element is housed from the opening into the cylindrical housing, the cover is fixed to the housing by riveting a disc-shaped cover to the opening of the housing.

[0263] In this cylindrical secondary battery (Comparative Example 1), the protruding length of the positive electrode lead is relatively long, and the positive electrode lead is not clamped by the cover and the battery element. As a result, in the space between the cover and the battery element, a portion of the positive electrode lead is not fixed and is in a free state, and a portion of the positive electrode lead is bent into an S-shape.

[0264] (Comparative Example 2)

[0265] By following the steps described below, a coin-shaped secondary battery with the positive lead not held by the outer can or battery element was manufactured. This secondary battery has the same structure as the secondary battery disclosed in Patent Document 2 (Japanese Patent Application Publication No. 10-154505).

[0266] The manufacturing steps of this coin-shaped secondary battery (Comparative Example 2) are the same as those of the coin-shaped secondary battery (Example 1), except as described below. In this case, two hollow container components, one open at one end and the other closed at the other, are riveted together to form an outer can that secures the battery element inside. Furthermore, the positive electrode lead is welded to one container component (the external connection terminal of the positive electrode) in the remaining space located to the side of the battery element, with the welding position of the positive electrode lead as the outermost periphery of the positive electrode. Similarly, the negative electrode lead is welded to another container component (the external connection terminal of the negative electrode) in the winding center space, with the welding position of the negative electrode lead as the innermost periphery of the negative electrode.

[0267] In this coin-shaped secondary battery (Comparative Example 2), a portion of the positive electrode lead is disposed in the remaining space, and the positive electrode lead is not held by the container component or the battery element. Thus, in the space between the container and the battery element, a portion of the positive electrode lead is not fixed and is in a free state, and the positive electrode lead is bent into an approximately V-shape.

[0268] [Performance Evaluation]

[0269] The performance (physical durability) of the secondary battery was evaluated, and the results are shown in Table 1. It should be noted that the "Positive Lead Clamping" column in Table 1 indicates whether the positive lead is clamped by the outer can and the battery element.

[0270] In evaluating physical durability, vibration tests were conducted on secondary batteries according to UN testing procedures to investigate whether the secondary battery (positive lead) was damaged. In this case, by setting the number of tests to 30, the number of secondary batteries with the positive lead cut off (number of defective cuts) and the number of secondary batteries with the positive lead detached from the positive electrode (number of defective detachments) were investigated.

[0271] [Table 1]

[0272] Table 1 (Number of vibration tests = 30)

[0273] Clipping of positive electrode lead Number of cutting failures Number of peeling failures Example 1 Yes 0 0 Comparative Example 1 No 10 2 Comparative Example 2 No 8 10

[0274] [Inspection]

[0275] As shown in Table 1, the physical durability of the secondary battery varies depending on the state of the positive lead inside the outer can (whether it is clamped in or not).

[0276] Specifically, when the positive electrode lead was not held by the outer can and battery components (Comparative Examples 1 and 2), the positive electrode lead moved violently during the vibration test. As a result, due to the breakage of the positive electrode lead, both the number of disconnected leads and the number of leads that detached occurred. In these cases, in particular, either the number of disconnected leads or the number of leads that detached occurred reached half of the total number of tests (30).

[0277] In contrast, when the positive lead is held between the outer casing and the battery element (Example 1), the positive lead hardly moves during the vibration test. Therefore, the positive lead is not damaged, and thus there are no instances of cut failures or detachment failures.

[0278] [Summarize]

[0279] As shown in Table 1, the battery element 40, comprising a positive electrode 41 and a negative electrode 42, is housed inside the outer can 10, insulated from the outer can 10, and has external terminals 20 mounted on the outer can 10. A positive electrode lead 51 is connected to each of the positive electrode 41 and the external terminals 20. When a portion of the positive electrode lead 51 is insulated from the outer can 10 and each of the negative electrodes 42, and is clamped by the outer can 10 and the battery element 40, the secondary battery (positive electrode lead) will not break even under external force (vibration). Therefore, excellent physical durability is achieved in the secondary battery.

[0280] The above description, which presents the present technology through one implementation method and embodiment, does not limit the structure of the present technology to the structure described in one implementation method and embodiment, and various modifications are possible.

[0281] Specifically, the case where the outer can is a welded can (non-curled can) has been described, but the structure of the outer can is not particularly limited, so it can also be a rolled can that has been riveted. In this rolled can, the separate storage part and the lid part are riveted together by gaskets.

[0282] Furthermore, although the case of a wound battery element structure has been described, the battery element structure is not particularly limited. Therefore, other element structures such as a stacked type with electrodes (positive and negative electrodes) stacked on top of each other, and a zigzag type with electrodes (positive and negative electrodes) folded into a Z-shape can be used.

[0283] Furthermore, although the case where lithium is used as the electrode reactant has been described, this electrode reactant is not particularly limited. Therefore, as mentioned above, the electrode reactant can be other alkali metals such as sodium and potassium, or alkaline earth metals such as beryllium, magnesium, and calcium. Additionally, the electrode reactant can also be other light metals such as aluminum.

[0284] The effects described in this specification are merely illustrative, and therefore the effects of this technology are not limited to those described in this specification. Thus, this technology can also achieve other effects.

Claims

1. A secondary battery, comprising: External components; The battery element, housed inside the external component, includes a first electrode and a second electrode; External terminals are mounted on the external component and are insulated from the external component; as well as Connecting wiring is provided to each of the first electrode and the external terminals. A portion of the connection wiring is insulated from the outer casing and each of the second electrodes, and is clamped by the outer casing and the battery element. The battery element also includes an insulating separator disposed between the first electrode and the second electrode. The upper end of the separator protrudes upwards more than the upper ends of the first electrode and the second electrode. The upper surface of the battery element is formed by the upper end of the separator. A portion of the connecting wire extends along the upper surface of the battery element. A wiring recess is formed at the upper end of the separator for a portion of the connecting wire to be engaged.

2. The secondary battery according to claim 1, wherein, The connection wiring is connected to the first electrode closer to the front side than the center of the battery element. A portion of the connecting wiring is held by the outer casing and the battery element closer to the front than the center of the battery element.

3. The secondary battery according to claim 2, wherein, The connecting wiring extends from a point closer to the front of the battery element than the center to a point further inward than the center of the battery element. A portion of the connecting wiring is also held by the outer casing and the battery element on a side further inside the center of the battery element.

4. The secondary battery according to any one of claims 1 to 3, wherein, The outer component includes a protrusion formed by bending the outer component in a manner that partially protrudes inward. A portion of the connecting wiring is held by the protrusion and the battery element.

5. The secondary battery according to claim 4, wherein, The external component includes a recess formed by the protrusion. The external terminal is housed inside the recess.

6. The secondary battery according to any one of claims 1 to 3, wherein, The height of the diaphragm is greater than the height of the second electrode. A portion of the connecting wiring is insulated from the second electrode via the diaphragm.

7. The secondary battery according to claim 6, wherein, The first electrode and the second electrode are wound around each other facing each other via the diaphragm. The connection wiring is connected to the first electrode at a position closer to the inner periphery than the outermost periphery of the first electrode.

8. The secondary battery according to any one of claims 1 to 3, wherein, The secondary battery also includes a first insulating component that covers the periphery of the connecting wiring. A portion of the connection wiring is insulated from the outer casing and each of the second electrodes via the first insulating component.

9. The secondary battery according to any one of claims 1 to 3, wherein, The secondary battery also includes a second insulating component disposed between the external component and the connecting wiring. A portion of the connecting wiring is insulated from the outer casing via the second insulating component.

10. The secondary battery according to any one of claims 1 to 3, wherein, The secondary battery also includes a third insulating component disposed between the battery element and the connecting wiring. A portion of the connecting wiring is insulated from the second electrode via the third insulating component.

11. The secondary battery according to any one of claims 1 to 3, wherein, The external components include: A housing component having an opening for housing the battery element inside; and The cover component, on which the external terminal is mounted, is welded to the receiving component at the opening. The connecting wiring is folded back more than once.

12. The secondary battery according to claim 11, wherein, The length of the connecting cable is more than half the outer diameter of the external component.

13. The secondary battery according to any one of claims 1 to 3, wherein, The secondary battery is a flat and cylindrical secondary battery.

14. The secondary battery according to any one of claims 1 to 3, wherein, The secondary battery is a lithium-ion secondary battery.

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