Battery unit and battery wiring unit

Abstract

Provided is a battery unit which has high reliability, while being suited to downsizing. The battery unit comprises a battery and a wiring unit. The battery has a first electrode terminal and a second electrode terminal. The wiring unit has flexible wiring boards which are respectively provided with a first connection terminal that is to be bonded to the first electrode terminal and a second connection terminal that is to be bonded to the second electrode terminal. At least one of the first connection terminal and the second connection terminal has a conductive member and a solder layer. The conductive member includes a first surface, a second surface, and a through hole penetrating therethrough from the first surface toward the second surface. The solder layer includes a first portion that covers at least a part of the first surface of the conductive member, a second portion that covers at least a part of the second surface of the conductive member, and a connection portion that passes through the through hole and connects the first portion and the second portion to each other.

Description

Technical Field

[0001] The present disclosure relates to a battery unit and a wiring unit for a battery used therein.

Background Art

[0002] Conventionally, a battery unit including a battery having a positive electrode terminal and a negative electrode terminal, and a flexible wiring board having wiring connected to the battery is known. Regarding the configuration of such a battery unit, various studies have been made (see, for example, Patent Document 1).

[0003] Patent Document 1 discloses, for example, a battery unit including a battery having a positive electrode terminal and a negative electrode terminal, a flexible substrate having a plurality of contact terminals respectively contacting the positive electrode terminal and the negative electrode terminal, and a fixing member for fixing the flexible substrate on the battery. The flexible substrate is arranged to cover at least a part of the battery and is fixed by the fixing member without being joined to the battery.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

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

[0006] Therefore, a battery unit having high reliability while accommodating miniaturization is desired.

[0007] A battery unit according to one embodiment of the present disclosure comprises a battery and a wiring unit. The battery has a first electrode terminal and a second electrode terminal. The wiring unit has a flexible wiring board provided with a first connection terminal joined to the first electrode terminal and a second connection terminal joined to the second electrode terminal. At least one of the first connection terminal and the second connection terminal has a conductive member and a solder layer. The conductive member includes a first surface, a second surface, and a through hole penetrating from the first surface to the second surface. The solder layer includes a first portion covering at least a portion of the first surface of the conductive member, a second portion covering at least a portion of the second surface of the conductive member, and a connecting portion connecting the first portion and the second portion through the through hole.

[0008] According to one embodiment of the battery unit of this disclosure, high reliability can be achieved while accommodating miniaturization.

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

[0010] [Figure 1A] Figure 1A is a perspective view showing an example of the overall configuration of a battery unit in one embodiment of the present disclosure. [Figure 1B] Figure 1B is a perspective view showing the external appearance of the secondary battery shown in Figure 1A. [Figure 2] Figure 2 is an exploded perspective view showing an example of the battery unit configuration shown in Figure 1A. [Figure 3A] Figure 3A is a cross-sectional view showing an example of the cross-sectional configuration of the battery unit shown in Figure 1A. [Figure 3B] Figure 3B is an enlarged cross-sectional view showing an example of a partial cross-sectional configuration of the battery unit shown in Figure 3A. [Figure 3C] Figure 3C is an enlarged cross-sectional view showing an example of a partial cross-sectional configuration of the battery unit shown in Figure 3A. [Figure 4] Figure 4 is a cross-sectional view showing a detailed configuration example of the secondary battery shown in Figure 1A. [Figure 5] FIG. 5 is a cross-sectional view showing a configuration example of the battery element shown in FIG. 4. [Figure 6] FIG. 6 is a perspective view showing a configuration example of the exterior can used in the manufacturing process of the secondary battery. [Figure 7] FIG. 7 is an exploded perspective view showing a configuration example of the battery unit as a first modification of one embodiment of the present disclosure. [Figure 8A] FIG. 8A is a perspective view showing an overall configuration example of the battery unit as a second modification of one embodiment of the present disclosure. [Figure 8B] FIG. 8B is an exploded perspective view showing an overall configuration example of the battery unit as a second modification of one embodiment of the present disclosure. [Figure 9] FIG. 9 is a perspective view showing a configuration example of the battery unit as a modification of the present disclosure. [Figure 10] FIG. 10 is an exploded perspective view showing a configuration example of the wiring unit shown in FIG. 9 in a developed state.

MODE FOR CARRYING OUT THE INVENTION

[0011] Hereinafter, one embodiment of the present disclosure will be described in detail with reference to the drawings. The order of explanation is as follows. 1. Battery unit 1-1. Configuration 1-2. Operation of the secondary battery 1-3. Manufacturing method 1-4. Action and effect 2. Modification

[0012] 1. Battery unit <1-1. Configuration> FIG. 1A is a perspective view showing an overall configuration example of a battery unit according to an embodiment of the present disclosure. As shown in FIG. 1A, this battery unit includes a secondary battery 1 and a wiring unit 2 attached to the secondary battery 1. Note that this battery unit may not include a circuit. The circuit mentioned here is, for example, a control circuit for controlling the charging operation of the secondary battery 1. However, the battery unit of the present disclosure is not limited to one that does not include such a control circuit, and for example, an electronic component including a control circuit may be provided in the wiring unit.

[0013] (1-1-1. Configuration of Secondary Battery) The secondary battery described here has a flat and columnar three-dimensional shape and is so-called coin-type and button-type. As will be described later, this secondary battery has a pair of bottoms facing each other and a side wall portion located between the pair of bottoms, and in this secondary battery, the height is smaller than the outer diameter. This "outer diameter" is the diameter (maximum diameter) of each of the pair of bottoms, and the "height" is the distance (maximum distance) from the surface of one bottom to the surface of the other bottom. In the present embodiment, the direction connecting one bottom and the other bottom is defined as the height direction Z.

[0014] The charge and discharge principle of the secondary battery is not particularly limited, but hereinafter, the case where the battery capacity is obtained by utilizing the occlusion and release of electrode reactants will be described. This secondary battery includes an electrolyte together with a positive electrode and a negative electrode. In this secondary battery, in order to prevent the deposition of electrode reactants on the surface of the negative electrode during charging, the charging capacity of the negative electrode is larger than the discharge capacity of the positive electrode. That is, the electrochemical capacity per unit area of the negative electrode is set to be larger than the electrochemical capacity per unit area of the positive electrode.

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

[0016] In the following example, we will consider the case where lithium is the electrode reactant. A secondary battery that obtains battery capacity by utilizing the intercalation and deintercalation of lithium is a so-called lithium-ion secondary battery. In this lithium-ion secondary battery, lithium is intercalated and deintercalated in an ionic state.

[0017] Figure 1B is a perspective view showing the external appearance of the secondary battery 1 shown in Figure 1A. For convenience, in the following explanation, the upper side of the paper in Figure 1B will be referred to as the upper side of the secondary battery, and the lower side of the paper in Figure 1B will be referred to as the lower side of the secondary battery.

[0018] The secondary battery 1 described here has a three-dimensional shape in which the height H is smaller than the outer diameter D, as shown in Figure 1B; that is, a flat and columnar three-dimensional shape. Here, the three-dimensional shape of the secondary battery 1 is flat and cylindrical. In this embodiment, the vertical direction of the paper in Figure 1B is defined as the height direction Z. Therefore, the height H represents the dimension in the height direction Z of the secondary battery 1. The outer diameter D represents the dimension in the direction perpendicular to the height direction Z of the secondary battery 1, that is, the dimension in the horizontal plane.

[0019] The dimensions of the secondary battery 1 are not particularly limited, but as an example, the outer diameter D is 3 mm to 30 mm and the height H is 0.5 mm to 70 mm. However, the ratio of the outer diameter D to the height H (D / H) is greater than 1. That is, the outer diameter D is greater than the height H. The upper limit of this ratio (D / H) is not particularly limited, but it is preferably 25 or less.

[0020] The secondary battery 1 has an upper surface 1US, a lower surface 1LS opposite to the upper surface 1US, and a side surface 1SS connecting the upper surface 1US and the lower surface 1LS. An external terminal 20, which serves as the first electrode terminal (positive electrode terminal), is exposed on the upper surface 1US. The bottom M2 of the outer casing 10, which serves as the second electrode terminal (negative electrode terminal), is exposed on the lower surface 1LS. The outer casing 10 has a storage section 11 and a lid section 12, and extends from the lower surface 1LS through the side surface 1SS to the outer edge of the upper surface 1US. The external terminal 20 is surrounded on the upper surface 1US by the peripheral portion 12R (described later) of the lid section 12, which is part of the outer casing 10. The detailed configuration of secondary battery 1 will be described later.

[0021] Figure 2 is an exploded perspective view showing an example of the configuration of the battery unit of this embodiment in a disassembled state. The battery unit of this embodiment further includes an insulating sheet 3 between the secondary battery 1 and the wiring unit 2. The insulating sheet 3 is an annular insulating paper with an opening 3K in the central region. Furthermore, the battery unit of this embodiment may further include an insulating sheet 4 located on the opposite side of the secondary battery 1 from the wiring unit 2, and an insulating sheet 5 located on the opposite side of the wiring unit 2 from the secondary battery 1.

[0022] (1-1-2. Wiring Unit) The wiring unit 2 has a flexible wiring board 21 on which a first connection terminal 31 and a second connection terminal 34 are provided. Figure 3A shows an example of the cross-sectional configuration of the battery unit. Figure 3B is an enlarged cross-sectional view of the first connection terminal 31 and its vicinity. Figure 3C is an enlarged cross-sectional view of the second connection terminal 34 and its vicinity.

[0023] [First connection terminal and second connection terminal] The first connection terminal 31 is a conductive member positioned opposite the external terminal 20 of the secondary battery 1 and electrically connected to the external terminal 20. The second connection terminal 34 is a conductive member positioned opposite the bottom M2 of the outer casing 10, which serves as the negative electrode terminal of the secondary battery 1, and electrically connected to the bottom M2.

[0024] The first connection terminal 31 is electrically connected to the external terminal 20 by solder. As shown in Figures 3A and 3B, the first connection terminal 31 has a conductive member 32 and a solder layer 33. The conductive member 32 is an annular thin plate or foil made of a conductive material. Specifically, copper foil can be used as the constituent material of the conductive member 32. As shown in Figure 3B, the conductive member 32 includes an upper surface 32U, a lower surface 32L, and an end surface 32T connecting the upper surface 32U and the lower surface 32L. The lower surface 32L faces the upper surface of the external terminal 20. The conductive member 32 includes a through hole 32K in its central region that penetrates from the upper surface 32U to the lower surface 32L. The end surface 32T is the inner wall surface of the through hole 32K. The solder layer 33 is a conductive layer comprising a first portion 331 that covers at least a part of the upper surface 32U of the conductive member 32, a second portion 332 that covers at least a part of the lower surface 32L of the conductive member 32, and a connecting portion 333 that connects the first portion 331 and the second portion 332 through the through hole 32K. The second portion 332 is sandwiched between the lower surface 32L of the conductive member 32 and the upper surface of the external terminal 20, firmly connecting them electrically and mechanically. Here, the external terminal 20 and the first connecting terminal 31 are soldered together through the opening 3K of the insulating sheet 3. That is, at least a part of the opposing regions of the external terminal 20 and the first connecting terminal 31 overlaps with the opening 3K in the height direction Z.

[0025] The second connection terminal 34 is electrically connected to the bottom M2 of the outer casing 10 by solder. As shown in Figures 3A and 3C, the second connection terminal 34 has a conductive member 35 and a solder layer 36. The conductive member 35 is an annular thin plate or foil made of a conductive material. Specifically, copper foil can be used as the constituent material of the conductive member 35. As shown in Figure 3C, the conductive member 35 includes an upper surface 35U, a lower surface 35L, and an end surface 35T connecting the upper surface 35U and the lower surface 35L. The upper surface 35U faces the lower surface of the bottom M2 of the outer casing 10, i.e., the lower surface 1LS of the secondary battery 1. The conductive member 35 includes a through hole 35K in its central region that penetrates from the upper surface 35U to the lower surface 35L. The end surface 35T is the inner wall surface of the through hole 35K. The solder layer 36 is a conductive layer comprising a first portion 361 that covers at least a part of the upper surface 35U of the conductive member 35, a second portion 362 that covers at least a part of the lower surface 35L of the conductive member 35, and a connecting portion 363 that connects the first portion 361 and the second portion 362 through the through hole 35K. The first portion 361 is sandwiched between the lower surface of the bottom M2 and the upper surface 35U of the conductive member 35, firmly connecting the two electrically and mechanically.

[0026] [Flexible wiring board] As shown in Figure 2, the flexible wiring board 21 has a first support portion 21U, a second support portion 21L, an intermediate portion 21M, and an output terminal portion 21C. The first support portion 21U is the portion that supports the first connection terminal 31. The first support portion 21U is positioned to face the upper surface 1US of the secondary battery 1. The second support portion 21L is the portion that supports the second connection terminal 34. The second support portion 21L is positioned to face the lower surface 1LS of the secondary battery 1. The intermediate portion 21M is the portion that connects the first support portion 21U and the second support portion 21L. The intermediate portion 21M is provided along the side surface 1SS of the secondary battery 1. The output terminal portion 21C has a first output terminal 24 and a second output terminal 27 for outputting the electromotive force of the secondary battery 1 to the outside. In the example of the wiring unit 2 shown in Figure 2, the output terminal section 21C is located on the opposite side from the intermediate section 21M when viewed from the first support section 21U. Figure 2In the first embodiment of the present disclosure, the flexible wiring board 21 is unfolded so that the first support portion 21U, the second support portion 21L, the intermediate portion 21M, and the output terminal portion 21C all spread out along the same plane. However, in the battery unit of one embodiment of the present disclosure, the first support portion 21U is bent almost vertically at the boundary portion between the intermediate portion 21M and the second support portion 21L is bent almost vertically at the boundary portion between the intermediate portion 21M.

[0027] As shown in Figure 2, the flexible wiring board 21 further includes a first wiring W1 extending from the first connection terminal 31 to the first output terminal 24, and a second wiring W2 extending from the second connection terminal 34 to the second output terminal 27, sequentially passing through the intermediate portion 21M and the first support portion 21U. The first wiring W1 and the second wiring W2 are printed wiring made of a highly conductive material such as copper. The first wiring W1 and the second wiring W2 are sandwiched between, for example, two flexible insulating films (the first layer F1 and the second layer F2 described later).

[0028] The first support portion 21U has a first insulating member 23 that holds the first connection terminal 31. As shown in Figures 3A and 3B, the first insulating member 23 has a laminated structure of a first layer F1 and a second layer F2. Between the first layer F1 and the second layer F2, there is a wiring layer 22 including a first wiring W1, etc. The first layer F1 and the second layer F2 are flexible insulating films such as polyimide film. The outer diameter of the first support portion 21U, and especially the outer diameter of the first insulating member 23, should be substantially the same as the outer diameter D of the secondary battery 1, or slightly smaller than the outer diameter D.

[0029] The intermediate section 21M is the part that connects the first support section 21U and the second support section 21L. The intermediate section 21M is integrated with the first support section 21U and the second support section 21L and has a laminated structure of a first layer F1 and a second layer F2. Between the first layer F1 and the second layer F2, a wiring layer 22 including a second wiring W2 is provided. The intermediate section 21M is provided along the side surface 1SS of the side wall section M3 of the secondary battery 1.

[0030] The second support portion 21L has a second insulating member 26 that holds the second connection terminal 34. As shown in Figures 3A and 3C, the second insulating member 26 has a laminated structure of a first layer F1 and a second layer F2, similar to the first insulating member 23. Between the first layer F1 and the second layer F2, a wiring layer 22 including a second wiring W2 is provided. The outer diameter of the second support portion 21L, and especially the outer diameter of the second insulating member 26, should be substantially the same as the outer diameter D of the secondary battery 1, or slightly smaller than the outer diameter D.

[0031] (1-1-3. Detailed configuration of the secondary battery) Figure 4 is a cross-sectional view showing a detailed configuration example of the secondary battery 1. As shown in Figure 4, the secondary battery 1 comprises an outer casing 10, external terminals 20, a gasket 30, a battery element 40, a positive electrode lead 51, a negative electrode lead 52, a sealant 61, and insulating films 62 and 63.

[0032] [Outer can] The outer casing 10 is a hollow outer component that houses the battery element 40 and other components. The outer casing 10 is made of a conductive material such as metal.

[0033] The outer casing 10 has a flat and cylindrical three-dimensional shape, corresponding to the flat and cylindrical three-dimensional shape of the secondary battery. The outer casing 10 has a pair of opposing bottoms M1 and M2, and a side wall M3 located between bottoms M1 and M2. That is, the side wall M3 connects bottoms M1 and M2 and surrounds the battery element 40. The upper end of the side wall M3 is connected to bottom M1. The lower end of the side wall M3 is connected to bottom M2. As described above, since the outer casing 10 is approximately cylindrical, the planar shapes of bottoms M1 and M2 are approximately circular, and the surface of the side wall M3 is a convex curved surface.

[0034] The outer container 10 includes a storage section 11 and a lid section 12 that are welded to each other. That is, the internal space of the outer container 10 is sealed by welding the lid section 12 to the storage section 11. In this embodiment, the bottom section M1 constitutes the lid section 12, and the bottom section M2 and the side wall section M3 are integrated to form the storage section 11. Therefore, the outer edge of the lid section 12 is welded to the end of the side wall section M3 opposite to the bottom section M2, i.e., the upper end of the side wall section M3.

[0035] The storage section 11 is a flat, cylindrical storage member that houses the battery element 40 and the like. The storage section 11 has a hollow structure with an open upper end and a closed lower end. That is, the storage section 11 has an opening 11K at its upper end, which serves as a passage through which the battery element 40 can be inserted in the height direction Z.

[0036] As shown in Figure 4, the lid 12 is a substantially disc-shaped lid member that closes the opening 11K of the storage compartment 11 and has a through-hole 12K. The through-hole 12K is used as a connection path for connecting the battery element 40 and the external terminal 20 to each other. As described above, the outer edge of the lid 12 is welded to the opening 11K of the storage compartment 11. The external terminal 20 is attached to the lid 12 via a gasket 30. That is, the lid 12 supports the external terminal 20 via the gasket 30. The external terminal 20 is attached to the lid 12 via the gasket 30 at a position that overlaps with the through-hole 12K of the lid 12 in the height direction Z. The external terminal 20 is electrically insulated from the outer casing 10.

[0037] Furthermore, in the completed secondary battery, as described above, the lid 12 is welded to the storage section 11. As mentioned above, the opening 11K is closed by the lid 12. Therefore, it is possible that by looking at the exterior of the secondary battery, it is not possible to confirm whether the storage section 11 had an opening 11K.

[0039] However, if the lid 12 is welded to the storage section 11, welding marks will remain on the surface of the outer can 10, more specifically at the boundary between the storage section 11 and the lid 12. Based on the presence or absence of these welding marks, it is possible to retrospectively confirm whether the storage section 11 had an opening 11K.

[0040] In other words, if welding marks remain on the surface of the outer can 10, it means that the storage compartment 11 had an opening 11K. On the other hand, if no welding marks remain on the surface of the outer can 10, it means that the storage compartment 11 did not have an opening 11K.

[0041] The lid portion 12 is bent so as to partially protrude along the height direction Z toward the interior of the storage portion 11, forming a recessed portion 12H. That is, when viewed from the outside of the outer casing 10, the lid portion 12 has a shape that is partially recessed in the height direction Z toward the battery element 40 housed inside the outer casing 10. The recessed portion 12H includes a through-hole 12K that penetrates in the height direction Z, a bottom portion 12HB that surrounds the through-hole 12K along a horizontal plane perpendicular to the height direction Z, and a wall portion 12HW that stands along the outer edge of the bottom portion 12HB. The portion of the lid portion 12 other than the recessed portion 12H is the peripheral portion 12R. The peripheral portion 12R is an annular shape that surrounds the recessed portion 12H in a horizontal plane perpendicular to the height direction Z of the secondary battery. The peripheral portion 12R is the part that surrounds the recessed portion 12H and protrudes away from the battery element 40 along the height direction Z. Therefore, in the height direction Z, the surface 12HS of the bottom 12HB of the recessed portion 12H is lower toward the interior of the storage portion 11 than the surface 12RS of the peripheral portion 12R. In other words, in the height direction Z, the distance between the surface 12HS of the bottom 12HB of the recessed portion 12H and the battery element 40 is shorter than the distance between the surface 12RS of the peripheral portion 12R and the battery element 40.

[0042] The plan view shape of the recess 12H, that is, the shape defined by the outer edge of the recess 12H when the secondary battery is viewed from above, is not particularly limited. Here, the plan view shape of the recess 12H is approximately circular. The inner diameter D12H and depth of the recess 12H are not particularly limited and can be set arbitrarily. However, when the external terminal 20 is attached to the recess 12H via the gasket 30, the surface of the external terminal 20 20FS The depth of the recess 12H is set such that the height position of the recess 12H is lower than the height position of the surface 12RS of the peripheral portion 12R. In addition, the inner diameter D12H of the recess 12H is set to be larger than the outer diameter D20 of the external terminal 20.

[0043] As described above, the outer can 10 is a can in which the storage section 11 and the lid section 12, which were previously physically separated from each other, are welded together; in other words, it is a welded can. As a result, the outer can 10 after welding is a single, physically integrated component, and therefore cannot be separated into the storage section 11 and the lid section 12 afterward.

[0044] The outer can 10, which is a welded can, is a different type of can from a crimped can formed using a crimping process, and is a so-called crimp-pressed can. This is because the element space volume increases inside the outer can 10, thus increasing the energy density per unit volume. This "element space volume" refers to the volume (effective volume) of the internal space of the outer can 10 that can be used to house the battery elements 40.

[0045] Furthermore, the outer can 10, which is a welded can, does not have any overlapping parts, nor does it have any overlapping parts between two or more components.

[0046] "Having no overlapping parts" means that no part of the outer casing 10 is processed (bent) in a way that allows it to overlap with other parts. Furthermore, "Having no overlapping parts between two or more components" means that, after the secondary battery is completed, the outer casing 10 is physically a single component, and therefore cannot be subsequently separated into two or more components. In other words, the state of the outer casing 10 in the completed secondary battery is not one in which two or more components are combined while overlapping each other in a way that would allow for subsequent separation.

[0047] Here, the outer casing 10 is conductive. More specifically, the storage section 11 and the lid section 12 are both conductive. The outer casing 10 is electrically connected to the negative electrode 42 of the battery element 40 via the negative electrode lead 52. Therefore, the outer casing 10 also serves as an external connection terminal for the negative electrode 42. In this embodiment, the secondary battery 1 does not need to have an external connection terminal for the negative electrode 42 separate from the outer casing 10, thus suppressing the reduction in element space volume caused by the presence of an external connection terminal for the negative electrode 42. As a result, the element space volume increases, and therefore the energy density per unit volume increases.

[0048] Specifically, the outer can 10 is a metal can containing one or more types of conductive materials, such as metal materials and alloy materials. The conductive materials that make up the metal can include iron, copper, nickel, stainless steel, iron alloys, copper alloys, and nickel alloys. The type of stainless steel is not particularly limited, but specifically, it includes SUS304 and SUS316. However, the forming material of the storage section 11 and the forming material of the lid section 12 may be the same or different from each other.

[0049] The lid portion 12 is insulated from the external terminal 20, which serves as the external connection terminal for the positive electrode 41, via a gasket 30. This is to prevent contact, i.e., short circuits, between the outer casing 10, which is the external connection terminal for the negative electrode 42, and the external terminal 20, which is the external connection terminal for the positive electrode 41.

[0050] [External terminals] External terminal 20 is, 2 The next battery 1 is a connection terminal that is connected to the electronic device via the wiring unit 2 when the battery is installed in the electronic device. As described above, the external terminal 20 is attached to the lid 12 of the outer casing 10 and supported by the lid 12.

[0051] The external terminal 20 is connected to the positive electrode 41 of the battery element 40 via the positive electrode lead 51. Therefore, the external terminal 20 also serves as an external connection terminal for the positive electrode 41. As a result, when the secondary battery 1 is in use, the external terminal 20, which serves as an external connection terminal for the positive electrode 41, and the outer casing 10, which serves as an external connection terminal for the negative electrode 42, are connected to the electronic device via the wiring unit 2. Thus, the electronic device can operate using the secondary battery 1 as a power source.

[0052] The external terminal 20 is a flat, substantially plate-shaped member extending along a horizontal plane perpendicular to the height direction Z of the secondary battery. The plan view shape of the external terminal 20, that is, the shape defined by the outer edge of the external terminal 20 when the secondary battery is viewed from above, is not particularly limited. In the secondary battery 1 of this embodiment, the plan view shape of the external terminal 20 is substantially circular. The external terminal 20 is positioned inside the recess 12H via a gasket 30. That is, the external terminal 20 is provided in a state where it is housed within the recess 12H without protruding from it in the height direction Z. Therefore, Figure 3A As shown, in a cross-section along the height direction Z, the outer diameter D20 of the external terminal 20 is smaller than the inner diameter D12H of the recess 12H. Similarly, the outer diameter D31 of the first connection terminal 31 of the wiring unit 2 is also smaller than the inner diameter D12H of the recess 12H. Furthermore, it is desirable that the center position of the external terminal 20 coincides with the center line PC (described later) of the secondary battery.

[0053] The external terminal 20 is insulated from the lid portion 12 via the gasket 30. Here, as shown in FIG. 4, in the height direction Z, the position of the surface 20FS of the external terminal 20 is lower toward the battery element 40 than the position of the surface 12RS of the peripheral portion 12R of the outer can 10 even if it is the highest position. In the secondary battery 1 of the present embodiment, the height of the secondary battery 1 is smaller compared to the case where the external terminal 20 protrudes above the lid portion 12. For this reason, the energy density per unit volume of the secondary battery 1 increases. Also, it is possible to prevent a short circuit from occurring between the outer can 10 and the external terminal 20 via other conductive members. The external terminal 20 has a central portion 20C and a peripheral portion 20R surrounding the periphery of the central portion 20C The central portion 20C is a portion of the external terminal 20 that overlaps with the through-hole 12K of the lid portion 12. The positive electrode lead 51 is connected to the back surface 20BS of the central portion 20C. The peripheral portion 20R overlaps with the bottom portion 12HB of the recessed portion 12H in the height direction Z. By having an overlapping portion between the external terminal 20 and the lid portion 12, the mechanical strength of the entire secondary battery can be improved.

[0054] Note that, as shown in FIG. 3A Since the outer diameter D20 of the external terminal 20 is smaller than the inner diameter D12H of the recessed portion 12H (D20 < D12H), as shown in FIG. 4, the outer edge 20T of the external terminal 20 is separated from the lid portion 12. Thereby, the gasket 30 is disposed only in a part of the region between the external terminal 20 and the lid portion 12 (recessed portion 12H). More specifically, the gasket 30 is disposed only in a place where the external terminal 20 and the lid portion 12 could contact each other if the gasket 30 did not exist. However, the gasket 30 may also be provided between the inner wall surface of the wall portion 12HW of the recessed portion 12H and the outer edge 20T of the external terminal 20.

[0055] The external terminal 20 contains one or more conductive materials, such as metal materials and alloy materials. The external terminal 20 may consist of a single layer, or it may be a laminate containing two or more layers having different coefficients of thermal expansion. Specifically, the external terminal 20 may be a laminate of a first layer made of Ni (nickel), a second layer made of stainless steel such as SUS304, and a third layer made of Al (aluminum).

[0056] [gasket] Gasket 30 is, Figures 3A and 4 As shown, it is an insulating member positioned between the outer can 10 (lid portion 12) and the external terminal 20. The external terminal 20 is fixed to the lid portion 12 via the gasket 30. The gasket 30 has a ring-shaped planar form with a through-hole at a location corresponding to the through-hole 12K. The gasket 30 also contains one or more types of insulating materials, such as insulating polymer compounds, and these insulating materials are resins such as polypropylene and polyethylene.

[0057] The installation range of the gasket 30 can be set arbitrarily. Here, the gasket 30 is placed in the gap between the surface 12HS of the bottom 12HB of the recess 12H and the back surface 20BS of the external terminal 20. However, as mentioned above, it is preferable that the gasket 30 also be provided between the inner wall surface of the wall 12HW of the recess 12H and the outer edge 20T of the external terminal 20. Furthermore, it is preferable that the lid 12 and the external terminal 20 are fixed together by the gasket 30.

[0058] [Battery element] The battery element 40 is a power generation element that drives the charge-discharge reaction, as shown in Figure 3A And as shown in Figure 4, it is housed inside the outer casing 10. As shown in Figure 4, the battery element 40 includes a positive electrode 41 as the first electrode and a negative electrode 42 as the second electrode. Here, the battery element 40 further includes a separator 43 and an electrolyte solution which is a liquid electrolyte.

[0059] The center line PC shown in Figure 4 is a line segment corresponding to the center of the battery element 40 in the direction along the outer diameter D of the secondary battery (the outer casing 10). That is, the position of the center line PC P0 This corresponds to the center position of the battery element 40.

[0060] The battery element 40 is a so-called electrode winding 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. Furthermore, the stacked positive electrode 41, negative electrode 42 and separator 43 are wound around a central line PC, which is the winding axis. The positive electrode 41 and the negative electrode 42 are wound while maintaining a state of facing each other via the separator 43. For this reason, a winding center space 40K is formed at the center of the battery element 40 as an internal space.

[0061] Here, the positive electrode 41, the negative electrode 42, and the separator 43 are wound such that the separator 43 is positioned at the outermost circumference and innermost circumference of the wound electrode body, respectively. The number of turns for each of the positive electrode 41, the negative electrode 42, and the separator 43 is not particularly limited and can be set arbitrarily.

[0062] The battery element 40 has a three-dimensional shape that conforms to the three-dimensional shape of the outer casing 10. Specifically, the battery element 40 has a flattened and cylindrical three-dimensional shape. Compared to the case where the battery element 40 has a three-dimensional shape different from the three-dimensional shape of the outer casing 10, when the battery element 40 is housed inside the outer casing 10, so-called dead space, specifically the gap between the outer casing 10 and the battery element 40, is less likely to occur. As a result, the internal space of the outer casing 10 is effectively utilized. Consequently, the volume of the element space increases, and the energy density per unit volume of the secondary battery increases.

[0063] (positive electrode) Figure 5 is a cross-sectional view showing a partial configuration example of the battery element 40. The positive electrode 41 is the first electrode used to carry out the charge-discharge reaction, and as shown in Figure 5, it includes a positive electrode current collector 41A and a positive electrode active material layer 41B.

[0064] The positive electrode current collector 41A has a pair of surfaces on which the positive electrode active material layer 41B is provided. This positive electrode current collector 41A contains a conductive material such as a metal material, and the metal material is aluminum, for example.

[0065] The positive electrode active material layer 41B is provided on both sides of the positive electrode current collector 41A and contains one or more types of positive electrode active materials capable of intercalating and deintercalating lithium. However, the positive electrode active material layer 41B may be provided on only one side of the positive electrode current collector 41A. Furthermore, the positive electrode active material layer 41B may also contain a positive electrode binder and a positive electrode conductive agent. The method for forming the positive electrode active material layer 41B is not particularly limited, but specifically, it may be a coating method.

[0066] The positive electrode active material contains a lithium compound. This lithium compound is a general term for compounds that contain lithium as a constituent element, and more specifically, it is a compound that contains lithium along with one or more transition metal elements as constituent elements. This is because a high energy density can be obtained. However, the lithium compound may further contain one or more of any other elements (excluding lithium and transition metal elements). The type of lithium compound is not particularly limited, but specifically, it includes oxides, phosphoric acid compounds, silicate compounds, and borate compounds. Specific examples of oxides include LiNiO2, LiCoO2, and LiMn2O4, and specific examples of phosphoric acid compounds include LiFePO4 and LiMnPO4.

[0067] The positive electrode binder contains one or more of the following: synthetic rubber and polymer compounds. Synthetic rubber is styrene-butadiene rubber, while polymer compounds are polyvinylidene fluoride. The positive electrode conductive agent contains one or more of the following: carbon materials, and carbon materials are graphite, carbon black, acetylene black, and Ketjen black. However, the conductive material may also be a metal material or a polymer compound.

[0068] (Negative electrode) The negative electrode 42 is a second electrode used to advance the charge-discharge reaction. Figure 5 As shown, it includes a negative electrode current collector 42A and a negative electrode active material layer 42B.

[0069] The negative electrode current collector 42A has a pair of surfaces on which the negative electrode active material layer 42B is provided. This negative electrode current collector 42A contains a conductive material such as a metal material, and the metal material is such as copper.

[0070] The negative electrode active material layer 42B is provided on both sides of the negative electrode current collector 42A and contains one or more types of negative electrode active materials capable of intercalating and deintercalating lithium. However, the negative electrode active material layer 42B may be provided on only one side of the negative electrode current collector 42A. Furthermore, the negative electrode active material layer 42B may also contain a negative electrode binder and a negative electrode conductive agent. Details regarding the negative electrode binder and negative electrode conductive agent are the same as the details regarding the positive electrode binder and positive electrode conductive agent. The method for forming the negative electrode active material layer 42B is not particularly limited, but specifically, it is one or more types from among coating, gas phase, liquid phase, thermal spraying, and firing (sintering).

[0071] The negative electrode active material contains either or both carbon materials and metallic materials because they allow for high energy density. Carbon materials include easily graphitizable carbon, poorly graphitizable carbon, and graphite (natural graphite and artificial graphite). Metallic materials are materials that contain one or more metallic elements and metalloid elements capable of forming alloys with lithium, such as silicon and tin, either or both. However, metallic materials may be elements, alloys, compounds, mixtures of two or more of these, or materials containing two or more phases. Specific examples of metallic materials are TiSi2 and SiO2. x (0 <x≦2、または0.2<x<1.4)などである。

[0072] 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 both above and below the positive electrode 41. This is to prevent lithium released from the positive electrode 41 from being deposited. This "height" is the dimension corresponding to the height H of the secondary battery described above, that is, the vertical dimension in Figures 1B and 2, respectively. The definition of height explained here will remain the same throughout.

[0073] (Separator) As shown in Figures 4 and 5, the separator 43 is an insulating porous membrane placed between the positive electrode 41 and the negative electrode 42. The separator 43 allows lithium ions to pass through while preventing a short circuit between the positive electrode 41 and the negative electrode 42. The separator 43 contains a polymer compound such as polyethylene.

[0074] Here, the height of the separator 43 is greater than the height of the negative electrode 42. That is, the separator 43 should protrude both above and below the negative electrode 42. This is to use the separator 43 to insulate the positive electrode lead 51 from the negative electrode 42.

[0075] (electrolyte) The electrolyte is impregnated into the positive electrode 41, the negative electrode 42, and the separator 43, and contains a solvent and an electrolyte salt. The solvent contains one or more non-aqueous solvents (organic solvents) such as carbonate ester compounds, carboxylic acid ester compounds, and lactone compounds, and the electrolyte containing such a non-aqueous solvent is a so-called non-aqueous electrolyte. The electrolyte salt contains one or more light metal salts such as lithium salts.

[0076] [Positive lead] The positive lead 51 is housed inside the outer casing 10, as shown in Figure 4. The positive lead 51 is a connecting wire connected to the positive electrode 41 and the external terminal 20, respectively. Figure 4The secondary battery shown has one positive lead 51. However, the secondary battery may have two or more positive leads 51.

[0077] The positive lead 51 is connected to the upper end of the positive electrode 41. Specifically, the positive lead 51 is connected to the upper end of the positive electrode current collector 41A. The positive lead 51 is also connected to the external terminal 20 via the through-hole 12K provided in the cover portion 12. Back side 20BS It is connected to the positive lead 51. The method of connecting the positive lead 51 is not particularly limited, but specifically, it is one or more of the welding methods such as resistance welding and laser welding. The details regarding the welding methods described here are also the same hereafter.

[0078] A portion of the positive lead 51 is electrically insulated from the lid 12 of the outer casing 10 and the negative electrode 42 of the battery element 40, and is sandwiched between the lid 12 and the battery element 40 in the height direction of the secondary battery. Figure 4 As shown, the positive lead 51 includes a first portion 511, a second portion 512, and a folded portion 513. The first portion 511 and the second portion 512 extend along a horizontal plane perpendicular to the height direction Z of the secondary battery. The first portion 511 and the second portion 512 also overlap each other in the height direction Z of the secondary battery via the sealant 61. The folded portion 513 is curved to connect the first portion 511 and the second portion 512.

[0079] The first part 511 and the second part 512 are, in the height direction Z of the secondary battery, of the battery element 40 and the cover portion 12 Recessed section 12H It is sandwiched between them.

[0080] In this way, a portion of the positive electrode lead 51 extends along the lower surface of the lid 12 and the upper surface of the battery element 40, respectively, and is held in place by the lid 12 and the battery element 40. Therefore, the positive electrode lead 51 is fixed inside the outer casing 10. Even if the secondary battery is subjected to external forces such as vibration and shock, the positive electrode lead 51 is less likely to move, thus reducing the likelihood of damage to the positive electrode lead 51. Damage to the positive electrode lead 51 here refers to cracks occurring in the positive electrode lead 51, the positive electrode lead 51 being cut, or the positive electrode lead 51 being detached from the positive electrode 41.

[0081] In other words, the fact that a portion of the positive electrode lead 51 is sandwiched between the outer casing 10 and the battery element 40 means that the positive electrode lead 51 is insulated from both the outer casing 10 and the battery element 40, and is held in place from above and below by the outer casing 10 and the battery element 40. Therefore, even if the secondary battery is subjected to external forces such as vibration and shock, the positive electrode lead 51 is unlikely to move inside the outer casing 10. The fact that the positive electrode lead 51 is unlikely to move inside the outer casing 10 means that the battery element 40 is also unlikely to move inside the outer casing 10. Consequently, when the secondary battery is subjected to vibration or shock, malfunctions such as unwinding of the wound electrode body of the battery element 40 can be suppressed.

[0082] Furthermore, the positive electrode lead 51 may be embedded in the battery element 40 due to being pressed against it. More specifically, as described above, the height of the separator 43 is greater than the heights of the positive electrode 41 and the negative electrode 42, so the positive electrode lead 51 may be embedded in the upper end of the separator 43. In this case, a recess is formed in the upper end of the separator 43 due to the pressure of the positive electrode lead 51. Part or all of the positive electrode lead 51 is housed inside this recess, and the positive electrode lead 51 is held in place by the separator 43. The positive electrode lead 51 becomes less likely to move inside the outer casing 10, making it less likely to be damaged.

[0083] Here, as described above, the lid portion 12 includes a protrusion 12P, and a portion of the positive electrode lead 51 is sandwiched between the protrusion 12P and the battery element 40. That is, a portion of the positive electrode lead 51 extends along the lower surface of the protrusion 12P and the upper surface of the battery element 40, respectively, so that it is held by the protrusion 12P and the battery element 40. Since the positive electrode lead 51 is more easily held by utilizing the protrusion 12P, the positive electrode lead 51 becomes less likely to be damaged.

[0084] Furthermore, a portion of the positive electrode lead 51 is insulated from the lid portion 12 and the negative electrode 42 via the separator 43, sealant 61, and insulating film 62, respectively.

[0085] Specifically, as described above, the height of the separator 43 is greater than the height of the negative electrode 42. As a result, a portion of the positive electrode lead 51 is separated from the negative electrode 42 via the separator 43, and is therefore insulated from the negative electrode 42 via the separator 43. This prevents a short circuit between the positive electrode lead 51 and the negative electrode 42.

[0086] Furthermore, the positive lead 51 is surrounded by an insulating sealant 61. This insulates a portion of the positive lead 51 from the cover 12 and the negative electrode 42 via the sealant 61. This prevents short circuits between the positive lead 51 and the cover 12, as well as between the positive lead 51 and the negative electrode 42.

[0087] Furthermore, an insulating film 62 is placed between the lid 12 and the positive lead 51. This insulates a portion of the positive lead 51 from the lid 12 via the insulating film 62, thereby preventing a short circuit between the positive lead 51 and the lid 12.

[0088] Furthermore, an insulating film may also be placed between the battery element 40 and the positive electrode lead 51.

[0089] Details regarding the forming material of the positive electrode lead 51 are the same as details regarding the forming material of the positive electrode current collector 41A. However, the forming material of the positive electrode lead 51 and the forming material of the positive electrode current collector 41A may be the same or different.

[0090] Here, the positive lead 51 is connected to the positive electrode 41 in the region in front of the center line PC, that is, the region to the right of the center line PC in Figure 4. The positive lead 51 has a folded portion 513 on its way to the external terminal 20 in order to connect to the external terminal 20. The folded portion 513 is located in the region behind the center line PC, that is, the region to the left of the center line PC in Figure 4. The positive lead 51 is located from the point where it is connected to the positive electrode 41 to the center position P0 The positive electrode lead 51 has a first portion 511 as the part that passes through to the folded portion 513. The first portion 511 extends along the upper surface of the battery element 40 in a direction perpendicular to the height direction Z. Furthermore, the positive electrode lead 51 has a second portion 512 as the part that is intermediate from the folded portion 513 to the point where it is connected to the external terminal 20. The second portion 512 extends along the upper surface of the battery element 40 in a direction perpendicular to the height direction Z so as to cover the first portion 511. In this way, a part of the positive electrode lead 51 extends toward the external terminal 20 while being sandwiched between the cover portion 12 and the battery element 40 in both the region in front of the center line PC and the region behind the center line PC.

[0091] Here, the "region in front of the center line PC" is, as is clear from Figure 4, the region in which the battery element 40 is divided into two regions with respect to the center line PC in the direction along the outer diameter D, and the connection point of the positive electrode lead 51 to the positive electrode 41 exists. In Figure 4, the "region in front of the center line PC" is the region to the right of the center line PC. In contrast, the "region behind the center line PC" is, as is clear from Figure 4, the other of the two regions described above, and in Figure 4, it is the region to the left of the center line PC. That is, the "region behind the center line PC" is the other region in which the battery element 40 is divided into two regions with respect to the center line PC in the direction along the outer diameter D, and the connection point of the positive electrode lead 51 to the positive electrode 41 does not exist.

[0092] The connection position of the positive electrode lead 51 to the positive electrode 41 is not particularly limited and can be set arbitrarily. In particular, it is preferable that the positive electrode lead 51 is connected to the positive electrode 41 on the inner side of the positive electrode 41 rather than on the outermost side of the positive electrode 41. This is because, unlike when the positive electrode lead 51 is connected to the positive electrode 41 on the outermost side of the positive electrode 41, corrosion of the outer casing 10 caused by electrolyte creep is prevented. This "electrolyte creep" refers to the phenomenon where, when the positive electrode lead 51 is positioned close to the inner wall surface of the outer casing 10, the electrolyte in the battery element 40 creeps up the positive electrode lead 51 and reaches the inner wall surface of the outer casing 10. When the electrolyte comes into contact with the outer casing 10 due to this "electrolyte creep," the outer casing 10 may dissolve or discolor.

[0093] Here, the positive lead 51 is folded back at least once between the positive electrode 41 and the external terminal 20, so it is folded over at least once. The number of times the positive lead 51 is folded back is not particularly limited, as long as it is at least once. "The positive lead 51 is folded back" means that the direction of extension of the positive lead 51 changes so that it forms an angle greater than 90° at some point. The folded portion of the positive lead 51 may have a curved shape without bending, such as the folded portion 513. Also, although Figure 4 illustrates the case where the positive lead 51 includes one folded portion 513, it may also include multiple folded portions 513.

[0094] The positive lead 51 is folded back at the folded portion 513 located between the positive lead 41 and the external terminal 20. Specifically, Figure 4 As shown, the first portion 511 extends in a horizontal plane perpendicular to the height direction of the secondary battery from a first position P1 other than the center position P of the outer casing 10 to a second position P2 opposite to the first position P1 when viewed from the center position. The second portion 512 extends from the second position P2 toward the center position P. In the positive electrode lead 51, the overlapping portion of the first portion 511 and the second portion 512 is the surplus portion. In other words, the positive electrode lead 51 can be said to have a length margin in its longitudinal direction.

[0095] As a result, as will be described later, when forming the outer casing 10 using the storage section 11 and the lid section 12 in the secondary battery manufacturing process, there is room to change the orientation of the lid section 12 relative to the storage section 11. In addition, when the secondary battery is subjected to external forces such as vibration and shock, these external forces are mitigated by utilizing the length margin of the positive electrode lead 51, making the positive electrode lead 51 less susceptible to damage. Furthermore, by utilizing the length margin of the positive electrode lead 51, the connection position of the positive electrode lead 51 to the positive electrode 41 can be arbitrarily changed without changing the length of the positive electrode lead 51.

[0096] In this case, the length of the positive electrode lead 51 (total length including length margin) is not particularly limited and can be set arbitrarily. In particular, it is preferable that the length of the positive electrode lead 51 be at least half the outer diameter D of the outer can 10. This is because the length of the positive electrode lead 51 ensures a length margin for standing the lid 12 upright relative to the storage section 11, making it easier to stand the lid 12 upright relative to the storage section 11.

[0097] The connection range of the positive lead 51 to the external terminal 20 is not particularly limited. In particular, it is preferable that the connection range of the positive lead 51 to the external terminal 20 be wide enough to prevent the positive lead 51 from easily falling off the external terminal 20, and narrow enough to provide a sufficient length margin for the positive lead 51. The reason why a sufficiently narrow connection range of the positive lead 51 to the external terminal 20 is preferable is that the portion of the positive lead 51 not connected to the external terminal 20 becomes the length margin, thus making the length margin of the positive lead 51 sufficiently large.

[0098] The positive electrode lead 51 is provided separately from the positive electrode current collector 41A. However, since the positive electrode lead 51 is physically continuous with the positive electrode current collector 41A, it may be integrated with the positive electrode current collector 41A.

[0099] [Negative lead] The negative electrode lead 52 is housed inside the outer casing 10, as shown in Figure 4. The negative electrode lead 52 is connected to the negative electrode 42 and the outer casing 10 (storage section 11), respectively. Here, the secondary battery has one negative electrode lead 52. However, the secondary battery may have two or more negative electrode leads 52.

[0100] The negative electrode lead 52 is connected to the lower end of the negative electrode 42, and more specifically, to the lower end of the negative electrode current collector 42A. The negative electrode lead 52 is also connected to the bottom surface of the housing 11. Details regarding the connection method of the negative electrode lead 52 are the same as those regarding the connection method of the positive electrode lead 51.

[0101] Details regarding the forming material of the negative electrode lead 52 are the same as details regarding the forming material of the negative electrode current collector 42A. However, the forming material of the negative electrode lead 52 and the forming material of the negative electrode current collector 42A may be the same or different.

[0102] The connection position of the negative electrode lead 52 to the negative electrode 42 is not particularly limited and can be set arbitrarily. Here, the negative electrode lead 52 is connected to the outermost part of the negative electrode 42 that constitutes the wound electrode body.

[0103] The negative electrode lead 52 is provided separately from the negative electrode current collector 42A. However, since the negative electrode lead 52 is physically continuous with the negative electrode current collector 42A, it may be integrated with the negative electrode current collector 42A.

[0104] [Sealant] As shown in Figure 4, the sealant 61 is a first insulating member that covers the periphery of the positive electrode lead 51. The sealant 61 is constructed by attaching two insulating tapes to the front and back surfaces of the positive electrode lead 51, respectively. Here, the sealant 61 covers the periphery of the middle portion of the positive electrode lead 51 in order to connect the positive electrode lead 51 to the positive electrode 41 and the external terminal 20, respectively. Note that the sealant 61 is not limited to having a tape-like structure, but may also have a tubular structure, for example.

[0105] The sealant 61 contains one or more insulating materials, such as insulating polymer compounds, and these insulating materials include polyimide.

[0106] [Insulating film] As shown in Figure 4, the insulating film 62 is positioned between the lid portion 12 and the positive electrode lead 51 in the height direction Z. Here, the insulating film 62 has a ring-shaped planar form with an opening 62K at a location corresponding to the through-hole 12K in the height direction Z.

[0107] The insulating film 62 may have an adhesive layer (not shown) on one side and be bonded to either the lid portion 12 or the positive electrode lead 51 via this adhesive layer. Alternatively, the insulating film 62 may have adhesive layers on both sides and be bonded to both the lid portion 12 and the positive electrode lead 51 via these adhesive layers.

[0108] Furthermore, the insulating film 62 may contain one or more insulating materials, such as insulating polymer compounds. The insulating materials contained in the insulating film 62 are polyimide, etc.

[0109] As shown in Figure 4, the insulating film 63 is a third insulating member positioned 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 positioned to shield the winding center space 40K and to cover the battery element 40 around the winding center space 40K.

[0110] Details regarding the material for forming the insulating film 63 are the same as those regarding the material for forming the insulating film 62. However, the material for forming the insulating film 63 and the material for forming the insulating film 62 may be the same or different from each other.

[0111] [others] Furthermore, the secondary battery 1 may also include one or more other components.

[0112] Specifically, the secondary battery 1 is equipped with a safety valve mechanism. This safety valve mechanism disconnects the electrical connection between the outer casing 10 and the battery element 40 when the internal pressure of the outer casing 10 reaches a certain level. The causes of the internal pressure of the outer casing 10 reaching a certain level include a short circuit occurring inside the secondary battery 1 and the secondary battery being heated from the outside. The location of the safety valve mechanism is not particularly limited, but it is preferable that the safety valve mechanism be provided on either the bottom M1 or M2, and more preferably on the bottom M2 where the external terminal 20 is not attached.

[0113] Furthermore, the secondary battery 1 may include an insulator between the outer casing 10 and the battery element 40. This insulator includes one or more types of insulating films and insulating sheets, etc., and prevents short circuits between the outer casing 10 and the battery element 40. The installation range of the insulator is not particularly limited and can be set arbitrarily.

[0114] The outer container 10 is provided with an opening valve. This opening valve opens when the internal pressure of the outer container 10 reaches a certain level, thereby releasing the internal pressure. The location of the opening 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, with the bottom M2 being more preferred.

[0115] <1-2. Operation> During charging of the secondary battery 1, lithium is released from the positive electrode 41 in the battery element 40, and this lithium is absorbed into the negative electrode 42 via the electrolyte. Conversely, during discharging of the secondary battery, lithium is released from the negative electrode 42 in the battery element 40, and this lithium is absorbed into the positive electrode 41 via the electrolyte. During these charging and discharging processes, lithium is absorbed and released in an ionic state.

[0116] <1-3. Manufacturing method> Next, we will explain the manufacturing method of the battery unit.

[0117] (1-3-1. Method for manufacturing secondary batteries) First, the manufacturing method of the secondary battery 1 will be explained. Figure 6 shows a perspective view of the outer casing 10 used in the manufacturing process of the secondary battery 1, and corresponds to Figure 1B.

[0118] Figure 6 shows the state in which the lid 12 is separated from the storage section 11, before the lid 12 is welded to the storage section 11. In the following description, Figure 6 will be referred to as well as Figures 1A to 5, which have already been described.

[0119] Here, in order to form the outer container 10, a storage section 11 and a lid section 12, which are physically separated from each other, are prepared as shown in Figure 6. The storage section 11 is a substantially container-shaped member in which a bottom section 11B and a side wall section 11W are integrated with each other, and has an opening 11K. However, the storage section 11 may also be formed by preparing the bottom section 11B and the side wall section 11W separately and welding the side wall section 11W to the bottom section 11B. A protrusion 11P is provided on the inside of the side wall section 11W. The protrusion 11P is, for example, formed integrally with the side wall section 11W. Alternatively, the protrusion 11P may be formed separately from the side wall section 11W and attached to the inside of the side wall section 11W.

[0120] The lid portion 12 is a roughly plate-shaped member corresponding to the bottom portion M1, and as will be described later, the external terminals 20 are attached in advance to the lower surface of the lid portion 12 via a gasket 30 (omitted in Figure 6).

[0121] [Fabrication of the positive electrode] First, a positive electrode mixture is prepared by mixing positive electrode active material, positive electrode binder, and positive electrode conductive agent. Next, a paste-like positive electrode mixture slurry is prepared by adding the prepared positive electrode mixture to an organic solvent. Subsequently, the positive electrode mixture slurry is applied to both sides of the positive electrode current collector 41A to form a positive electrode active material layer 41B. Finally, the positive electrode active material layer 41B is compressed and molded using a roll press or the like. In this case, the positive electrode active material layer 41B may be heated, or the compression molding may be repeated multiple times. This produces the positive electrode 41.

[0122] [Fabrication of the negative electrode] The negative electrode 42 is manufactured using the same procedure as the positive electrode 41. Specifically, after preparing the negative electrode current collector 42A, a negative electrode mixture, which consists of a negative electrode active material, a negative electrode binder, and a negative electrode conductive agent, is added to an organic solvent to prepare a paste-like negative electrode mixture slurry. Next. Next, a negative electrode active material layer 42B is formed by applying a negative electrode mixture slurry to both sides of the negative electrode current collector 42A. After this, the negative electrode active material layer 42B is compressed and molded using a roll press or the like. This produces the negative electrode 42.

[0123] [Preparation of electrolyte solution] The electrolyte salt is added to the solvent. This disperses or dissolves the electrolyte salt in the solvent, thus preparing the electrolyte solution.

[0124] [Assembly of rechargeable batteries] First, using a welding method such as resistance welding, the positive lead 51, which is covered with sealant 61, is connected to the positive electrode 41 (positive electrode current collector 41A), and the negative lead 52 is connected to the negative electrode 42 (negative electrode current collector 42A).

[0125] Next, the positive electrode 41 and the negative electrode 42 are stacked with a separator 43 in between, and then the stacked body including the positive electrode 41, the negative electrode 42, and the separator 43 is wound up, Figure 6 As shown, the wound body 40Z is fabricated. The wound body 40Z has the same configuration as the battery element 40, except that the positive electrode 41, negative electrode 42, and separator 43 are not impregnated with electrolyte. Figure 6 Therefore, the illustrations of the positive lead 51 and the negative lead 52 have been omitted.

[0126] Next, the winding body 40Z, to which the positive lead 51 and the negative lead 52 are connected, is housed inside the storage section 11 through the opening 11K. At this time, the winding body 40Z is housed in the space below the protrusion 11P, that is, in the space between the protrusion 11P and the bottom 11B in the height direction Z. In this case, the negative lead 52 is connected to the storage section 11 using a welding method such as resistance welding. Subsequently, an insulating film 63 is placed on top of the winding body 40Z.

[0127] Next, a cover portion 12 is prepared, which already has the external terminals 20 attached via a gasket 30 and an insulating film 62 provided. Then, the positive lead 51 is connected to the external terminals 20 via the through-hole 12K using a welding method such as resistance welding.

[0128] As a result, the wound body 40Z (positive electrode 41) housed inside the storage section 11 and the external terminal 20 attached to the lid section 12 are connected to each other via the positive electrode lead 51.

[0129] Next, electrolyte is injected into the storage section 11 through the opening 11K. In this case, as described above, even though the battery element 40 and the external terminal 20 are connected to each other via the positive electrode lead 51, the lid 12 does not block the opening 11K, so the electrolyte can be easily injected into the storage section 11 through the opening 11K. As a result, the electrolyte is impregnated into the wound body 40Z, which includes the positive electrode 41, the negative electrode 42, and the separator 43, and the battery element 40, which is a wound electrode body, is fabricated.

[0130] Next, the lid 12 is tilted down so that it approaches the storage compartment 11, thereby closing the opening 11K with the lid 12, and then the lid 12 is welded to the storage compartment 11 using a welding method such as laser welding. In this case, Figure 4 As shown, a portion of the positive lead 51 is sandwiched between the lid 12 and the battery element 40, and the positive lead 51 is positioned further than the connection point to the external terminal 20. back A curved folded portion 513 is formed in this manner. This completes the formation of the outer casing 10, and the battery elements 40 and the like are housed inside the outer casing 10, thus completing the assembly of the secondary battery 1.

[0131] [Stabilization of secondary batteries] The assembled secondary battery 1 is charged and discharged. Various conditions such as ambient temperature, number of charge / discharge cycles, and charge / discharge conditions can be set arbitrarily. As a result, a coating is formed on the surface of the negative electrode 42, etc., and the state of the secondary battery 1 is electrochemically stabilized. Thus, the secondary battery 1 is completed.

[0132] (1-3-2. Method for manufacturing wiring units) Next, the manufacturing method of the wiring unit 2 will be explained with reference to Figures 2 and 3A to 3C.

[0133] First, a flexible wiring board 21 is fabricated. Specifically, a first layer F1 and a second layer F2 are obtained by punching out two flexible insulating films into predetermined shapes. Next, a conductive member 32 is attached to the area of ​​the second layer F2 that will become the first insulating member 23, and a conductive member 35 is attached to the area of ​​the second layer F2 that will become the second insulating member 26. Furthermore, a first wiring W1 and a second wiring W2 are formed in predetermined areas of the second layer F2 by printing or other means. After that, the first layer F1 is superimposed on the second layer F2 so that the conductive member 32, conductive member 35, first wiring W1, and second wiring W2 are sandwiched between them. Furthermore, a first output terminal 24 to which the first wiring W1 is connected and a second output terminal 27 to which the second wiring W2 is connected are formed at the end of the second layer F2.

[0134] Next, a solder layer 33 is applied to the upper surface 32U and lower surface 32L of the conductive member 32, and a solder layer 36 is applied to the upper surface 35U and lower surface 35L of the conductive member 35.

[0135] With the above steps, wiring unit 2 is completed.

[0136] (1-3-3. Method for manufacturing a battery unit) Next, the first connection terminal 31 of the wiring unit 2 is brought into contact with the surface 20FS of the external terminal 20 of the secondary battery 1, and then the solder layer 33 is melted to electrically and mechanically solder the first connection terminal 31 to the external terminal 20. Furthermore, the second connection terminal 34 of the wiring unit 2 is brought into contact with the lower surface 1LS of the bottom M2 of the outer casing 10 of the secondary battery 1, and then the solder layer 36 is melted to electrically and mechanically solder the second connection terminal 34 to the lower surface 1LS of the bottom M2.

[0137] By performing the above operations, a battery unit according to one embodiment of the present disclosure is completed.

[0138] <1-4. Mechanism and Effects> As described above, in the battery unit of one embodiment of this disclosure, a wiring unit 2 is provided in the secondary battery 1, so that the flexible wiring board 21 in the wiring unit 2 can electrically connect the external terminal 20, which serves as the positive terminal of the secondary battery 1, and the outer casing 10, which serves as the negative terminal, to external equipment.Here, a flexible wiring board 21 is adopted which has a structure in which a first wiring W1 and a second wiring W2 are sandwiched between two flexible insulating films, a first layer F1 and a second layer F2, so that an electrical short circuit between the positive electrode 41 and the negative electrode 42 can be avoided, and a relatively flexible wiring layout can be realized.

[0139] Furthermore, in one embodiment of the battery unit of this disclosure, the first connection terminal 31 is soldered to the external terminal 20 by a solder layer 33. Here, the solder layer 33 has a structure in which a first portion 331, a second portion 332, and a connecting portion 333 are integrated, extending continuously from the upper surface 32U of the conductive member 32 through the end surface 32T to the lower surface 32L. As a result, the wiring unit 2 can be thin while still being able to firmly connect the first connection terminal 31 to the external terminal 20 electrically and mechanically. Similarly, the solder layer 36 that solders the second connection terminal 34 to the bottom M2 of the outer casing 10 has a structure in which a first portion 361, a second portion 362, and a connecting portion 363 are integrated, extending continuously from the upper surface 35U of the conductive member 35 through the end surface 35T to the lower surface 35L. As a result, the wiring unit 2 can be thin while still being able to firmly connect the second connection terminal 34 to the bottom M2 electrically and mechanically. Therefore, it is possible to avoid connection failures between the first connection terminal 31 and the external terminal 20, and connection failures between the second connection terminal 34 and the bottom M2, caused by external factors such as shocks and vibrations applied from outside the battery unit. Furthermore, since the battery unit of this embodiment does not include circuits in the wiring unit 2, etc., it is not necessary to consider the effect of heat generated during soldering on the circuits. Therefore, the battery unit of this embodiment can achieve high reliability while accommodating miniaturization.

[0140] The above is one implementation form. attitudeAs explained above, the structure of this disclosure is one implementation form In a state The configuration is not limited to the one described, and can be modified in various ways.

[0141] Specifically, the layout of the flexible wiring board of the wiring unit is not limited to the flexible wiring board 21 described in the above embodiment. Figure 7 is an exploded perspective view showing a battery unit 100A of a first modified example of one embodiment of the present disclosure. The battery unit 100A in Figure 7 includes a wiring unit 2A. The wiring unit 2A has a flexible wiring board 21A. The flexible wiring board 21A has a first support portion 21U, a second support portion 21L, an intermediate portion 21M, and an output terminal portion 21C, similar to the flexible wiring board 21 shown in Figure 2. However, in the flexible wiring board 21A, the intermediate portion 21M has a connecting portion 28 that connects the first support portion 21U and the second support portion 21L, and a lead portion 29 that branches off from the connecting portion 28. Of the lead portion 29, the end opposite to the connecting portion 28 is provided with an output terminal portion 21C. The connecting portion 28 and the lead portion 29 are integrated and have a laminated structure of a first layer F1 and a second layer F2, similar to the first insulating member 23. The connecting portion 28 and the lead portion 29 are provided with a first wiring W1 and a second wiring W2 sandwiched between the first layer F1 and the second layer F2. In the example of the wiring unit 2A shown in Figure 7, the first wiring W1 extends from the first connection terminal 31 through the connecting portion 28 and the lead portion 29 to the first output terminal 24. The second wiring W2 extends from the second connection terminal 34 through the connecting portion 28 and the lead portion 29 to the second output terminal 27.

[0142] Furthermore, in the battery unit 100 of the above embodiment, the first connection terminal 31 of the wiring unit 2 is connected to the upper surface 1US of the secondary battery 1, and the second connection terminal 34 of the wiring unit 2 is connected to the lower surface 1LS of the secondary battery 1. However, the present disclosure is not limited thereto. For example, as shown in Figures 8A and 8B, in the battery unit 100B, a second modification of one embodiment of the present disclosure, the first connection terminal 31 of the wiring unit 2B is connected to the upper surface 1US of the secondary battery 1, and the second connection terminal 34 of the wiring unit 2B is connected to the side surface 1SS of the secondary battery 1. Even in that case, the battery unit 100B can obtain the same effects as the battery unit 100 of the above embodiment. Figure 8A is a perspective view showing an example of the overall configuration of the battery unit 100B as a second modification of one embodiment of the present disclosure. Figure 8B is an exploded perspective view showing an example of the overall configuration of the battery unit 100B. The battery unit 100B includes a wiring unit 2B. The wiring unit 2B has a flexible wiring board 21B including, for example, a roughly L-shaped trunk section 25. A second connection terminal 34 is provided at the first end of the trunk section 25, and an output terminal section 21C is provided at the second end of the trunk section 25. A first insulating member 23 is connected to the region between the second connection terminal 34 and the output terminal section 21C of the trunk section 25 via a connecting portion 28. The first insulating member 23 supports the first connection terminal 31. The wiring unit 2B is defined as the boundary between the first insulating member 23 and the connecting portion 28. The department By being bent almost vertically, the first connection terminal 31 faces the upper surface 1US of the secondary battery 1, and the second connection terminal 34 faces the side surface 1SS of the secondary battery 1.

[0143] Furthermore, although the above-described embodiment of the battery unit described the case where the outer casing 10 is a welded casing (crimped casing), the structure of the outer casing is not particularly limited, and a crimped casing may also be used. In this crimped casing, the storage section and the lid section, which are separated from each other, are crimped together via a gasket.

[0144] Furthermore, while we have described the case where the electrode reactant is lithium, the electrode reactant is not particularly limited. Therefore, as mentioned above, the electrode reactant may be other alkali metals such as sodium and potassium, or alkaline earth metals such as beryllium, magnesium, and calcium. In addition, the electrode reactant may be other light metals such as aluminum.

[0145] Furthermore, while the above-described embodiment of the battery unit has been explained in which a secondary battery is provided as the battery, this disclosure is not limited thereto, and a primary battery may also be provided. Figure 9 is a perspective view showing an example of the configuration of a battery unit 100C as a modification of this disclosure, in which a primary battery 9 is provided instead of a secondary battery 1. The battery unit of the above-described embodiment comprises a secondary battery 1 and a wiring unit 2 having a flexible wiring board 21 on which a first connection terminal 31 and a second connection terminal 34 are provided. In contrast, the battery unit 100C of Figure 9 comprises a wiring unit 90 instead of the wiring unit 2.

[0146] Figure 10 is an exploded perspective view showing an example of the configuration of the wiring unit 90 shown in Figure 9 in an unfolded state. The wiring unit 90 has a flexible wiring board 91, for example, on which a first connection terminal 81 and a second connection terminal 84 are provided. The first connection terminal 81 is a conductive member that is positioned opposite the positive terminal 9A of the primary battery 9 and is electrically connected to the positive terminal 9A by soldering or the like. The second connection terminal 84 is a conductive member that is positioned opposite the bottom surface 9B of the outer casing, which serves as the negative terminal of the primary battery 9, and is electrically connected to the bottom surface 9B of the outer casing by soldering or the like. The flexible wiring board 91 has a first support portion 91U, a second support portion 91L, an intermediate portion 91M, and an output terminal portion 91C.

[0147] The first support portion 91U is the part that supports the first connection terminal 81. The first support portion 91U is provided so as to face the positive terminal 9A exposed on the surface of the primary battery 9. The second support portion 91L is the part that supports the second connection terminal 84. The second support portion 91L is provided so as to face the bottom surface 9B of the primary battery 9. The intermediate portion 91M is the part that connects the first support portion 91U and the second support portion 91L. The intermediate portion 91M is provided along the side surface of the primary battery 9. In Figure 10, the flexible wiring board 91 is shown unfolded so that the first support portion 91U, the second support portion 91L, and the intermediate portion 91M all spread out along the same plane. However, in the battery unit 100C, the first support portion 91U is bent almost vertically at the boundary between the intermediate portion 91M and the second support portion 91L is bent almost vertically at the boundary between the intermediate portion 91M and the first support portion 91U. The primary battery 9 has a height H1 that is lower than the height H of the secondary battery 1. Therefore, in the battery unit 100C equipped with the primary battery 9, the length of the intermediate portion 91M of the flexible wiring board 91 is shorter than the length of the intermediate portion 21M of the flexible wiring board 21 (Figure 2).

[0148] As shown in Figure 10, the flexible wiring board 91 further includes a first wiring W1 extending from the first connection terminal 81 through the intermediate portion 91M and the second support portion 91L to the first output terminal 97, and a second wiring W2 extending from the second connection terminal 84 to the second output terminal 94. The first wiring W1 and the second wiring W2 are printed wiring made of a highly conductive material such as copper. The first wiring W1 and the second wiring W2 are sandwiched between two flexible insulating films (for example, polyimide films).

[0149] The first support portion 91U has a first insulating member 93 that holds the first connection terminal 81. The intermediate portion 91M is the part that connects the first support portion 91U and the second support portion 91L. The intermediate portion 91M is integrated with the first support portion 91U and the second support portion 91L. The intermediate portion 91M is Primary battery 9 It is provided along the side surface. The second support portion 91L has a second insulating member 96 that holds the second connection terminal 84.

[0150] In the battery unit 100C shown in Figures 9 and 10, the electromotive force of the primary battery 9 can be extracted from the output terminal 91C.

[0151] The effects described herein are illustrative only, and the effects of this technology are not limited to those described herein. Therefore, other effects may be obtained with respect to this technology.

[0152] Furthermore, this disclosure may take the following forms: <1> A battery having a first electrode terminal and a second electrode terminal, A wiring unit having a flexible wiring board provided with a first connection terminal joined to the first electrode terminal and a second connection terminal joined to the second electrode terminal, respectively. Equipped with, At least one of the first connection terminal and the second connection terminal has a conductive member and a solder layer, The conductive member includes a first surface, a second surface, and a through hole that penetrates from the first surface toward the second surface. The solder layer includes a first portion covering at least a part of the first surface of the conductive member, a second portion covering at least a part of the second surface of the conductive member, and a connecting portion connecting the first portion and the second portion through the through hole. Battery unit. <2> The aforementioned battery is The external terminal as the first electrode terminal, The outer casing, which serves as the second electrode terminal, includes a bottom portion facing the external terminal and a side wall portion erected along the outer edge of the bottom portion. has the above <1> The battery unit as described. <3> The wiring unit further comprises an insulating layer provided between the external terminal and the wiring unit. The external terminal is surrounded by the upper end of the side wall portion. The insulating layer includes an opening, The external terminal and the first connection terminal are soldered together through the opening. the above <2> The battery unit as described. <4> The aforementioned flexible wiring board is A first support portion that supports the first connection terminal, A second support portion that supports the second connection terminal, An intermediate portion connecting the first support portion and the second support portion, A first wiring extending from the first connection terminal through the intermediate section to the intermediate section, Includes a second wiring that extends from the second connection terminal through the intermediate portion to the intermediate portion. the above <1> from <3> The battery unit listed in any one of the following. <5> The battery has a lid portion that holds the first electrode terminal, and a housing member that serves as the second electrode terminal, which includes a bottom portion facing the lid portion and a side wall portion that is erected along the outer edge of the bottom portion. The intermediate portion is provided along the side wall portion of the battery. the above <1> from <4> The battery unit listed in any one of the following. <6> A battery wiring unit that can be attached to a battery having a first electrode terminal and a second electrode terminal, The flexible wiring board includes a first connection terminal joined to the first electrode terminal and a second connection terminal joined to the second electrode terminal, At least one of the first connection terminal and the second connection terminal has a conductive member and a solder layer, The conductive member includes a first surface, a second surface, and a through hole that penetrates from the first surface toward the second surface. The solder layer includes a first portion covering at least a part of the first surface of the conductive member, a second portion covering at least a part of the second surface of the conductive member, and a connecting portion connecting the first portion and the second portion through the through hole. Battery unit.

Claims

1. A battery having a first electrode terminal and a second electrode terminal, A wiring unit having a flexible wiring board, a first connection terminal provided on the flexible wiring board and joined to the first electrode terminal, and a second connection terminal provided on the flexible wiring board and joined to the second electrode terminal. Equipped with, At least one of the first connection terminal and the second connection terminal has a conductive member and a solder layer, The conductive member includes a first surface, a second surface, and a through hole extending from the first surface toward the second surface. The solder layer includes a first portion that covers at least a part of the first surface of the conductive member, a second portion that covers at least a part of the second surface of the conductive member, and a connecting portion that connects the first portion and the second portion through the through hole. The aforementioned flexible wiring board is A first support portion that supports the first connection terminal, A second support portion that supports the second connection terminal, An intermediate portion connecting the first support portion and the second support portion, An output terminal section having a first output terminal and a second output terminal, A first wiring extending from the first connection terminal through the intermediate portion to the first output terminal, The second wiring extends from the second connection terminal, sequentially passing through the intermediate portion and the first support portion, to the second output terminal, The battery has a lid portion that holds the first electrode terminal, and a housing member that serves as the second electrode terminal, which includes a bottom portion facing the lid portion and a side wall portion that is erected along the outer edge of the bottom portion. The intermediate portion is provided along the side wall portion of the battery. Battery unit.

2. The aforementioned battery is Having an external terminal as the first electrode terminal The battery unit according to claim 1.

3. The wiring unit further comprises an insulating layer provided between the external terminal and the wiring unit. The external terminal is surrounded by the upper end of the side wall portion. The insulating layer includes an opening, The external terminal and the first connection terminal are soldered together through the opening. The battery unit according to claim 2.

4. A battery wiring unit that can be attached to a battery having a first electrode terminal and a second electrode terminal, Flexible wiring board and A first connection terminal is provided on the flexible wiring board and is joined to the first electrode terminal, A second connection terminal provided on the flexible wiring board and joined to the second electrode terminal It has, At least one of the first connection terminal and the second connection terminal has a conductive member and a solder layer, The conductive member includes a first surface, a second surface, and a through hole extending from the first surface toward the second surface. The solder layer includes a first portion that covers at least a part of the first surface of the conductive member, a second portion that covers at least a part of the second surface of the conductive member, and a connecting portion that connects the first portion and the second portion through the through hole. The aforementioned flexible wiring board is A first support portion that supports the first connection terminal, A second support portion that supports the second connection terminal, An intermediate portion connecting the first support portion and the second support portion, An output terminal section having a first output terminal and a second output terminal, A first wiring extending from the first connection terminal through the intermediate portion to the first output terminal, The second wiring extends from the second connection terminal, sequentially passing through the intermediate portion and the first support portion, to the second output terminal, The battery has a lid portion that holds the first electrode terminal, and a housing member that serves as the second electrode terminal, which includes a bottom portion facing the lid portion and a side wall portion that is erected along the outer edge of the bottom portion. The intermediate portion is provided along the side wall portion of the battery. Battery wiring unit.

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