Secondary batteries

Abstract

The objective is to provide a secondary battery that ensures insulation. [Solution] The secondary battery of the embodiment comprises an electrode group having current-collecting tabs on opposite sides, an electrode group having current-collecting tabs on opposite sides, an outer case housing the electrode group having a rectangular opening having a long side and a short side, a long side surface formed with the long side as one side, and a short side surface formed with the short side as one side, a lid member disposed in the opening, a conductive member having a substrate portion provided between the electrode group and the lid member, and a leg portion in contact with the current-collecting tabs, and an insulator having a first portion provided between the leg portion and the long side surface of the conductive member, and a second portion continuous with the first portion and provided between the current-collecting tab and the short side surface. The insulator has an overlapping portion between the insulators in the first portion, and at least a part of the overlapping portion is provided on the leg portion of the conductive member.

Description

TECHNICAL FIELD

[0001] Embodiments of the present invention relate to a secondary battery.

BACKGROUND ART

[0002] In recent years, secondary batteries such as lead-acid batteries and nickel-metal hydride batteries have been used as power sources typified by electric vehicles, hybrid vehicles, electric motorcycles, forklifts and the like. Recently, development toward the adoption of lithium ion secondary batteries with high energy density has been active, and development is being carried out while giving consideration to long life, safety and the like.

[0003] In a general lithium ion secondary battery (hereinafter referred to as a secondary battery), an electrode group is housed in a metallic outer case. In order to extract the energy of the electrode group to the outside, a conductive member may be connected to the electrode group inside the outer case. In this case, for example, when the electrode group expands due to gas generated from the electrode group, or when heat is generated from the outside or the inside, the conductive member may be deformed accordingly. The deformed conductive member comes into contact with the inner wall of the outer case, which may cause a short circuit in the secondary battery.

PRIOR ART DOCUMENTS

PATENT DOCUMENTS

[0004]

PATENT DOCUMENT 1

PATENT DOCUMENT 2

SUMMARY OF THE INVENTION

PROBLEMS TO BE SOLVED BY THE INVENTION

[0005] The problem to be solved by the present invention is to provide a secondary battery that ensures insulating properties.

MEANS FOR SOLVING THE PROBLEMS

[0006] To solve the above problems, the secondary battery of the embodiment comprises an electrode group having current-collecting tabs on opposite sides, formed by winding or stacking electrodes and separators, the electrode group having current-collecting tabs on opposite sides, an outer case housing the electrode group having a rectangular opening having a long side and a short side, a long side surface formed with the long side as one side, and a short side surface formed with the short side as one side, a lid member disposed in the opening, a conductive member having a substrate portion provided between the electrode group and the lid member, and a leg portion in contact with at least one of the current-collecting tabs, and an insulator having a first portion provided between the leg portion and the long side surface of the conductive member, and a second portion continuous with the first portion and provided between at least one of the current-collecting tabs and the short side surface. The insulator has an overlapping portion between the insulators in the first portion. At least a part of the overlapping portion is provided on the leg portion of the conductive member. [Brief explanation of the drawing]

[0007] [Figure 1] A schematic perspective view showing a secondary battery according to the first embodiment. [Figure 2] A schematic perspective view showing the secondary battery of the first embodiment disassembled into its individual components. [Figure 3] A cross-sectional view of the area around the insulator, seen from the direction of the arrow, along line II in Figure 1. [Figure 4] A cross-sectional view of the area around modified example 1 of the insulator, seen from the direction of the arrow, along line II in Figure 1. [Figure 5] A cross-sectional view of the area around modified example 2 of the insulator, viewed from the direction of the arrow along line II in Figure 1. [Figure 6] A cross-sectional view of the area around modified example 3 of the insulator, viewed from the direction of the arrow along line II in Figure 1. [Figure 7] A schematic perspective view showing the secondary battery of the second embodiment disassembled into its components. [Figure 8] In the secondary battery of the second embodiment, this is a cross-sectional view of the area around the insulator, viewed from the direction of the arrow along line II in Figure 1. [Modes for carrying out the invention]

[0008] The secondary battery 1 of this embodiment will be described below with reference to the drawings.

[0009] (First Embodiment) The secondary battery 1 of the first embodiment will be described with reference to Figures 1 and 2. Figure 1 is a schematic perspective view showing the secondary battery 1 of the first embodiment, and Figure 2 is a schematic perspective view showing the secondary battery 1 of the first embodiment disassembled into its components.

[0010] As shown in Figures 1 and 2, the secondary battery 1 comprises an outer case 3, an electrode group 5 housed within the outer case 3, and an electrolyte (not shown). The outer case 3 is, for example, cylindrical in shape, and is provided with a rectangular opening 9 having a long side 12 and a short side 14. The outer case 3 has a long side surface 3a formed with the long side 12 of the opening 9 as one side, and a short side surface 3b formed with the short side 14 of the opening 9 as one side. A lid member 7 is placed in this opening 9, and the outer case 3 and the lid member 7 are made of a metal such as aluminum, aluminum alloy, iron, copper, or stainless steel.

[0011] The electrode group 5 is manufactured, for example, by winding the electrode 13 and a separator (not shown) around an axis, and then press-molding the entire assembly into a flattened cross-sectional shape. This press-molding is performed to reduce the volume of the electrode group 5 within the outer casing 3. The electrode 13 has an electrode current collector (not shown) and an electrode active material carrying portion (not shown) supported on the electrode current collector. The electrode current collector includes a current collecting tab 70 as an uncoated portion of the electrode active material carrying portion. In the electrode group 5 of this embodiment, the current collecting tabs 70 are provided leading out from opposite sides of the electrode group 5, with one current collecting tab 70 on the opposite side being the positive electrode current collecting tab and the other current collecting tab 70 on the opposite side being the negative electrode current collecting tab. The electrode group 5 may also be manufactured by laminating the electrode 13 and the separator.

[0012] The electrode group 5 is housed inside the outer case 3 (in the Z direction). In this case, to prevent contact between the electrode group 5 and the outer case 3 and cause a short circuit, the area around the electrode group 5 is insulated by covering it with an insulating film 34. However, the insulating film 34 does not cover the current-collecting tabs 70 of the electrode group 5.

[0013] In this embodiment, when current-collecting tabs 70 are provided on opposite sides of the electrode group 5, it is preferable that the tips of the current-collecting tabs 70 are clamped by two or more metal members 16. Here, clamping means that the metal members 16 bundle and integrate multiple layers of current-collecting tabs 70, and it is sufficient that at least a part of the metal members 16 is in contact with one surface and the other surface of the current-collecting tab 70. This allows the current-collecting tabs 70 to be stably clamped by the metal members 16, for example, when the weight of the electrode group 5 is increased as a means of increasing the capacity of the secondary battery 1. Here, increasing the weight of the electrode group 5 refers to cases where the dimensions of the electrode group 5 are increased or the number of turns of the electrode 13 is increased in order to increase the mass of the electrode active material in the electrode group 5. The number of metal members 16 placed on each of the current-collecting tabs 70 at both ends of the electrode group 5 is not limited to these, and it is preferable that at least one of the current-collecting tabs 70 is clamped by one or more metal members 16.

[0014] A conductive member 31 is provided inside the outer casing 3 to extract the electrical energy from the electrode group 5 to the outside. Here, the conductive member 31 has a substrate portion 31a provided between the electrode group 5 and the lid member 7, and leg portions 31b provided between the electrode group 5 and the long side surface 3a of the outer casing 3. In this embodiment, the conductive member 31 has two leg portions 31b for each substrate portion 31a, but the number of leg portions 31b is not limited to these.

[0015] And the leg portion 31b of the conductive member 31 is connected to at least one of the current collecting tabs 70 of the electrode group 5. The term "connected" herein may mean that the leg portion 31b is directly connected to the current collecting tab 70, or may be connected to the metal member 16 that clamps the current collecting tab 70. When the leg portion 31b of the conductive member 31 is connected to the metal member 16, tearing of the current collecting tab 70 during connection can be suppressed as compared with the case where the leg portion 31b of the conductive member 31 is directly connected to the current collecting tab 70. When the conductive member 31 has two leg portions 31b for one substrate portion 31a, the current collecting tab 70 can be sandwiched between the two leg portions 31b from both sides in the thickness direction (Y direction) of the electrode group 5, so that displacement of the electrode group 5 in the Y direction due to external vibration or the like can be suppressed by the leg portions 31b.

[0016] The conductive member 31 may further be connected to the terminal 23 disposed on the surface of the lid member 7. In addition, a terminal insulator 35 may be provided between the terminal 23 and the lid member 7, whereby the terminal 23 and the lid member 7 are electrically insulated.

[0017] In the secondary battery 1 of the present embodiment, the lid member 7 is provided with the liquid injection port 17 together with the gas discharge valve 21, but the liquid injection port 17 may not be provided. In addition, between the substrate portion 31a of the conductive member 31 and the lid member 7, an insulating electrode group presser 33 may be provided to insulate the two members from each other.

[0018] Further, in the present embodiment, the current collecting tab 70 and the leg portion 31b of the conductive member 31 connected to the current collecting tab 70 are electrically insulated from the outer case 3 by the insulator 36 provided between the current collecting tab 70 and the outer case 3. The insulator 36 of the present embodiment includes, on at least one side of the current collecting tab 70, a first portion 36a provided between the leg portion 31b of the conductive member 31 and the long side surface 3a of the outer case 3, and a second portion 36b that is continuous with the first portion 36a and provided between the current collecting tab 70 and the short side surface 3b of the outer case 3.

[0019] The insulator 36 used in the secondary battery 1 of the present embodiment will be described with reference to FIG. 3. FIG. 3 is a cross-sectional view of the vicinity of the insulator 36, showing the cross section taken along line I-I of FIG. 1 as viewed from the direction of the arrows. As shown in FIG. 3, the insulator 36 has a two-layer overlapping portion 50 of the insulator 36 itself at the first portion 36a of the insulator 36, and at least a part of the overlapping portion 50 is provided on the leg portion 31b of the conductive member 31. Here, the overlapping portion 50 refers to the region R in FIG. 3, and the overlapping portion 50 overlaps in the thickness direction (Y direction) of the electrode assembly 5. Here, the overlapping portion 50 is Z-folded perpendicularly to the storage direction of the electrode assembly 5, that is, the height direction (Z direction) of the secondary battery 1, and is preferably provided parallel to the Z direction, but is not limited thereto.

[0020] In FIG. 3, the length of the leg portion 31b of the conductive member 31 in the width direction (X direction) of the secondary battery 1 is shorter than the length of the current collecting tab 70 in the X direction, but is not limited thereto, and the length of the leg portion 31b in the X direction may be longer than the length of the current collecting tab 70 in the X direction.

[0021] In the present embodiment, since the overlapping portion 50 of the insulator 36 is provided on the leg portion 31b of the conductive member 31, even if the leg portion 31b of the conductive member 31 is deformed when the electrode assembly 5 expands due to gas generated from the electrode assembly 5, or when heat is generated from the outside or the inside, the overlapping portion 50 of the insulator 36 follows the deformed leg portion 31b. Thereby, even when the leg portion 31b of the conductive member 31 is deformed, the two layers of the insulator 36 formed by the overlapping portion 50 always exist between the leg portion 31b and the inner wall of the exterior case 3, so that the deformed leg portion 31b can be prevented from piercing through the insulator 36. Therefore, contact between the leg portion 31b of the conductive member 31 and the inner wall of the exterior case 3 can be suppressed, and the secondary battery 1 that ensures insulation between the leg portion 31b of the conductive member 31 and the inner wall of the exterior case 3 can be provided.

[0022] In this context, deformation of the legs 31b of the conductive member 31 occurs, for example, when gas is generated from the electrode group 5 due to overcharging. In this case, the generated gas causes the electrode group 5 to expand in the thickness direction (Y direction), and the legs 31b also spread toward the inner wall of the outer case 3 (Y direction). Furthermore, if heat is generated from the outside or inside, the legs 31b deform due to the heat. In this case, deformation may occur not only in the Y direction but also in the width direction (X direction) and height direction (Z direction) of the secondary battery 1.

[0023] Specifically, if the legs 31b of the conductive member 31 spread toward the inner wall of the outer case 3 (in the Y direction), the overlapping portion 50 of the insulator 36 follows the direction in which the legs 31b deform toward the inner wall of the outer case 3 (in the Y direction), and the Z-bend portion opens in the Y direction. Furthermore, even if the legs 31b deforms not only in the Y direction but also in the X and Z directions, the two layers of overlapping portion 50 are provided to cover the legs 31b in the X and Z directions, thereby preventing the deformed legs 31b from piercing the insulator 36 or protruding from the insulator 36 and coming into contact with the inner wall of the outer case 3.

[0024] The method for providing the insulator 36 in this embodiment will now be explained. First, the starting point P is placed on the insulating film 34 of the electrode group 5 in Figure 3. Then, the first portion 36a is provided toward the end (X direction) of the current collector tab 70 and along the long side surface 3a of the outer case 3, in close contact with the leg portion 31b of the conductive member 31. While providing the first portion 36a, the insulator 36 is folded into a Z shape to provide an overlap portion 50. Subsequently, the first portion 36a is provided toward the end (X direction) of the current collector tab 70. Then, the second portion 36b is provided along the short side surface 3b of the outer case 3 in the same manner as described above, and the first portion 36a with the overlap portion 50 is provided toward the endpoint Q along the other long side surface 3a and in close contact with the leg portion 31b of the other conductive member 31. The endpoint Q of the insulator 36 is on the insulating film 34 of the electrode group 5. Here, the overlapping portion 50 only needs to be provided on at least one of the first portion 36a of the insulator 36, and should be provided on the side on which the leg portion 31b of the conductive member 31 is provided.

[0025] Furthermore, in Figure 3, the overlapping portion 50 is located inside the boundary U between the current collector tab 70 and the insulating film 34 (on the current collector tab 70 side). This ensures that the overlapping portion 50 is long enough to follow the spread of the legs 31b of the conductive member 31, and minimizes the proportion occupied by the overlapping portion 50 within the secondary battery 1. Although the overlapping portion 50 is thick because it consists of two layers of insulator 36, minimizing the proportion occupied by this overlapping portion 50 within the secondary battery 1 makes it possible to increase the capacity of the electrode group 5 within the secondary battery 1 by increasing the dimensions of the electrode group 5 or increasing the number of turns of the electrodes 13.

[0026] The insulator 36 is preferably formed from a single tape or plate, and more preferably from a tape, from the viewpoint of ease of installation. The method of installing the insulator 36 in this embodiment is as described above, but tape is easily deformable and overlapping portions 50 can be easily created. Specifically, tapes made of polyimide or meta-aramid fibers can be used, but are not limited to these. For example, Kapton® or Nomex® can be used. The tape used is preferably adhesive, and the starting point P and ending point Q of the insulator 36 are preferably bonded to the insulating film 34 of the electrode group 5.

[0027] As a result, even if the legs 31b of the conductive member 31 deform, the positional displacement of the insulator 36 can be suppressed because the starting point P and ending point Q of the insulator 36 are fixed to the insulating film 34, and there will always be two layers of insulator 36 between the legs 31b and the inner wall of the outer case 3 due to the overlapping portion 50. Furthermore, since the insulator 36 is provided covering the boundary U between the current collector tab 70 and the insulating film 34, the winding misalignment of the insulating film 34 relative to the electrode group 5 can also be suppressed by the insulator 36.

[0028] As mentioned above, the overlapping portion 50 is not limited to a Z-fold. For example, the overlapping portion 50 when the insulator 36 uses two tapes will be explained with reference to Figure 4. Figure 4 is a cross-sectional view of the area around modified example 1 (insulator 361) of the insulator 36, viewed from the direction of the arrow along line II in Figure 1. As shown in Figure 4, when the insulator 36' is made up of two tapes, the overlapping portion 50 may be provided so that the two tapes overlap.

[0029] The maximum length R of the overlapping portion 50 is preferably 0.50 or less of the maximum length D of the first portion 36a of the insulator 36. By having the length R of the overlapping portion 50 be 0.50 or less of the length D of the first portion 36a, the ratio of length R to length D is appropriate, and as the overlapping portion 50 opens in the Y direction, the starting point P of the insulator 36 is pulled by the overlapping portion 50, which suppresses the peeling of the starting point P from the insulating film 34. This suppresses displacement of the insulator 36 within the secondary battery 1.

[0030] A second modification of the insulator 36 of the first embodiment will be described with reference to Figure 5. Figure 5 is a cross-sectional view of the area around the second modification of the insulator 36 (insulator 362), viewed from the direction of the arrow along line II in Figure 1. The difference between the insulator 362 of the second modification shown in Figure 5 and the insulator 36 in Figure 3 is the position where the overlapping portion 50 is provided; otherwise, it is the same as the insulator 36 in Figure 3. The overlapping portion 50 in Figure 5 is provided outside the boundary U between the current collector tab 70 and the insulating film 34 (on the insulating film 34 side). The overlapping portion 50 provided outside the boundary U is bonded to the insulating film 34.

[0031] As a result, the overlapping portion 50 is long enough to follow the spread of the leg portion 31b of the conductive member 31, and since the overlapping portion 50 located outside the boundary portion U is bonded to the insulating film 34, displacement of the insulator 36 can be suppressed not only at the starting point P and ending point Q but also at the overlapping portion 50, and a two-layer insulator 36 formed by the overlapping portion 50 is always present between the leg portion 31b and the inner wall of the outer case 3.

[0032] Furthermore, a third modification of the insulator 36 of the first embodiment will be described with reference to Figure 6. Figure 6 is a cross-sectional view of the area around the third modification of the insulator 36 (insulator 363) as seen from the direction of the arrow along line II in Figure 1. The only difference between the insulator 363 of the third modification shown in Figure 6 and the insulator 36 in Figure 3 is the position where the overlapping portion 50 is provided; otherwise, it is the same as the insulator 36 in Figure 3.

[0033] The method for providing the insulator 363 in the modified example 3 will now be explained. Similar to the insulator 36 in Figure 3, first a first portion 36a having an overlapping portion 50 is provided from the starting point P, and then it is folded into a Z shape in order to provide another overlapping portion 50 while providing the second portion 36b. Here, it is preferable that the overlapping portion 50 of the second portion 36b overlaps in the width direction (X direction) of the electrode group 5, is provided at both ends of the second portion 36b, and is longer than the thickness of the leg portion 31b of the conductive member 31. Specifically, it is preferable that the longest length F of the overlapping portion 50 of the second portion 36b in the direction parallel to the short side 14 of the short side surface 3b of the outer case 3 is longer than the thickness S of the leg portion 31b of the conductive member 31 in the direction parallel to the short side 14. After providing the overlapping portion 50 of the second portion 36b, the first portion 36a having an overlapping portion 50 is provided up to the end point Q, similar to the insulator 36 in Figure 3.

[0034] As mentioned above, the leg portion 31b of the conductive member 31 may deform not only in the Y direction but also in the X and Z directions. In this case, even if the leg portion 31b deforms in the X direction and deforms to the point where it approaches the second portion 36b, the overlapping portion 50 of the second portion 36b follows the deformed leg portion 31b. As a result, even if the leg portion 31b of the conductive member 31 deforms to approach the second portion 36b in the X direction, there is always a two-layer insulator 36 formed by the overlapping portion 50 between the leg portion 31b and the inner wall of the outer case 3, so that the deformed leg portion 31b does not break through the second portion 36b of the insulator 36.

[0035] Furthermore, the length F of the overlapping portion 50 of the second part 36b is longer than the thickness S of the leg portion 31b of the conductive member 31. Therefore, even if the leg portion 31b of the conductive member 31 deforms and spreads in the X direction, a sufficiently long overlapping portion 50 opens in the X direction, and a two-layer insulator 36 formed by the overlapping portion 50 always exists between the leg portion 31b and the inner wall of the outer case 3.

[0036] The secondary battery 1 of the first embodiment described above has an insulator 36, and the insulator 36 has a two-layer overlapping portion 50 in the first portion 36a, and at least a part of the overlapping portion 50 is provided on the leg portion 31b of the conductive member 31. The overlapping portion 50 overlaps in the thickness direction (Y direction) of the electrode group 5.

[0037] In this embodiment, since the overlapping portion 50 of the insulator 36 is provided on the leg portion 31b of the conductive member 31, even if the leg portion 31b of the conductive member 31 deforms due to expansion of the electrode group 5 caused by gas generated from the electrode group 5, or due to heat generated from the outside or inside, the overlapping portion 50 of the insulator 36 follows the deformed leg portion 31b. As a result, even if the leg portion 31b of the conductive member 31 deforms, there is always a two-layer insulator 36 formed by the overlapping portion 50 between the leg portion 31b and the inner wall of the outer case 3, so that the deformed leg portion 31b does not break through the insulator 36. Therefore, contact between the leg portion 31b of the conductive member 31 and the inner wall of the outer case 3 can be suppressed, and a secondary battery 1 can be provided that ensures insulation between the leg portion 31b of the conductive member 31 and the inner wall of the outer case 3.

[0038] (Second embodiment) The secondary battery 1' of the second embodiment will be described with reference to Figure 7. Figure 7 is a schematic perspective view showing the secondary battery 1' of the second embodiment disassembled into its components. The difference between the secondary battery 1' of the second embodiment and the secondary battery 1 of the first embodiment is that the secondary battery 1' has an insulating cover 20.

[0039] The insulating cover 20 has a side member 20a provided between the leg portion 31b of the conductive member 31 and the first portion 36a of the insulator 36, and a back member 20b provided between at least one of the current collector tabs 70 and the second portion 36b of the insulator 36. The electrode group 5 of the secondary battery 1' may be displaced due to external vibrations and shocks, but the insulating cover 20 plays a role in suppressing the displacement of the electrode group 5. The insulating cover 20 is preferably provided at both ends of the current collector tab 70, which is sufficient to suppress the displacement of the electrode group 5 in the X direction, but is not limited to these. Furthermore, since the insulating cover 20 also plays a role in ensuring insulation between the current collector tab 70 and the outer case 3, it is preferable that the side member 20a is provided outside the boundary U between the current collector tab 70 and the insulating film 34 (on the insulating film 34 side).

[0040] The structure around the insulator 36 used in the secondary battery 1' of this embodiment will be described with reference to Figure 8. Figure 8 is a cross-sectional view of the area around the insulator 36 in the secondary battery 1' of the second embodiment, viewed from the direction of the arrow along the line II in Figure 1. The insulator 36 shown in Figure 8 is the same as the insulator 36 shown in Figure 3, but differs in that the overlapping portion 50 of the insulator 36 is provided on the leg portion 31b of the conductive member 31 and on the side member 20a of the insulating cover 20.

[0041] In the secondary battery 1' of the second embodiment, the overlapping portion 50 of the insulator 36 is provided on the side member 20a of the insulating cover 20. This allows the overlapping portion 50 of the insulator 36 to follow the deformed legs 31b even if the legs 5 expand due to gas generated from the electrode group 5, or if heat is generated from the outside or inside. As a result, even if the legs 31b of the conductive member 31 are deformed, there is always a two-layer insulator 36 formed by the overlapping portion 50 between the legs 31b and the inner wall of the outer case 3, and the side member 20a of the insulating cover 20 is also present, thus preventing the deformed legs 31b from piercing the insulator 36. Therefore, contact between the legs 31b of the conductive member 31 and the inner wall of the outer case 3 can be suppressed, and a secondary battery 1' can be provided that ensures insulation between the legs 31b of the conductive member 31 and the inner wall of the outer case 3.

[0042] In this case, if heat is generated from the outside or inside, the leg portion 31b may deform due to the heat, and the insulating cover 20 may also deform. In this case, the leg portion 31b will deform not only in the Y direction but also in the width direction (X direction) and height direction (Z direction) of the secondary battery 1'. However, even in this case, the two overlapping portions 50 are provided to cover the leg portion 31b in the X and Z directions, which prevents the deformed leg portion 31b from piercing the insulator 36. Furthermore, even if the insulating cover 20 deforms and the leg portion 31b protrudes from the insulating cover 20, the overlapping portions 50 provided on the insulating cover 20 prevent the leg portion 31b from coming into contact with the inner wall of the outer case 3.

[0043] The secondary battery 1 of at least one embodiment described above has an insulator 36, and the insulator 36 has a two-layer overlap 50 in the first portion 36a, and at least a part of the overlap 50 is provided on the leg portion 31b of the conductive member 31. The overlap 50 overlaps in the thickness direction (Y direction) of the electrode group 5.

[0044] Because the overlapping portion 50 of the insulator 36 is provided on the leg portion 31b of the conductive member 31, even if the leg portion 31b of the conductive member 31 deforms due to expansion of the electrode group 5 caused by gas generated from the electrode group 5, or due to heat generated from the outside or inside, the overlapping portion 50 of the insulator 36 follows the deformed leg portion 31b. As a result, even if the leg portion 31b of the conductive member 31 deforms, there is always a two-layer insulator 36 formed by the overlapping portion 50 between the leg portion 31b and the inner wall of the outer case 3, so that the deformed leg portion 31b does not break through the insulator 36. Therefore, contact between the leg portion 31b of the conductive member 31 and the inner wall of the outer case 3 can be suppressed, and a secondary battery 1 can be provided that ensures insulation between the leg portion 31b of the conductive member 31 and the inner wall of the outer case 3.

[0045] While several embodiments of the present invention have been described, these embodiments are presented as examples only and are not intended to limit the scope of the invention. These embodiments can be carried out in a variety of other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their variations are included in the scope and spirit of the invention, as well as in the claims and their equivalents. [Explanation of symbols]

[0046] 1...Secondary battery, 3...Outer case, 3a...Long side, 3b...Short side, 5...Electrode group, 7...Lid member, 9...Opening, 12...Long side, 13...Electrode, 14...Short side, 16...Metal member, 17...Filling port, 20...Insulating cover, 20a...Side member, 20b...Back member, 21...Gas discharge valve, 23...Terminal, 31...Conductive member, 31a...Substrate part, 31b...Legs, 34...Insulating film, 35...Terminal insulator, 36...Insulator, 36a...First part, 36b...Second part, 50...Overlapping part, 70...Current collector tab.

Claims

1. An electrode having a current-collecting tab and a separator are wound or stacked, and the electrode group has the current-collecting tab on opposite sides, An outer case having a rectangular opening with a long side and a short side, a long side surface formed with the long side as one side, and a short side surface formed with the short side as one side, and housing the electrode group, A lid member placed in the opening, A conductive member having a substrate portion provided between the electrode group and the cover member, and a leg portion connected to at least one of the current collecting tabs, The conductive member comprises a first portion provided between the leg portion and the long side surface of the conductive member, and an insulator having a second portion continuous with the first portion and provided between at least one of the current collecting tabs and the short side surface, The insulator has an overlapping portion of the insulators in the first portion, At least a portion of the overlapping portion is a secondary battery provided on the leg portion of the conductive member.

2. The secondary battery according to claim 1, wherein the overlapping portion is Z-folded perpendicular to the direction in which the electrode group is housed.

3. At least a portion of the electrode group is covered with an insulating film. The secondary battery according to claim 1, wherein at least a portion of the overlapping portion is bonded to the insulating film.

4. The secondary battery according to claim 1, wherein the insulator also has the overlapping portion in the second portion.

5. The secondary battery according to claim 1, further comprising an insulating cover having a side member provided between the legs of the conductive member and the first portion, and a back member provided between at least one of the current collecting tabs and the second portion.

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