Secondary batteries

Abstract

This product provides a highly safe rechargeable battery with excellent vibration resistance. [Solution] The secondary battery of the embodiment includes a positive electrode, a negative electrode, and a separator, and has at least one end an electrode group having a plurality of layers of current-collecting tabs led out from the positive electrode and the negative electrode, and an outer case housing the electrode group. The current-collecting tab has a first clamping portion whose tip is clamped by an insulating cover, and an outgoing portion provided from the first clamping portion toward the one end of the electrode group and covered by the insulating cover.

Description

Technical Field

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

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, and forklifts. Recently, development towards the adoption of lithium-ion secondary batteries with high energy density has been actively carried out, and development has been carried out while considering long life, safety, and the like.

[0003] As one form of a general lithium-ion secondary battery (hereinafter referred to as a secondary battery), there is a secondary battery including an exterior case, an electrode group housed in the exterior case, a current collector tab led out from the electrode group, and positive and negative electrode leads joined to the current collector tab. Such secondary batteries are used in various applications. For example, when mounted on a vehicle, the secondary battery vibrates due to the vibration during running. Along with this vibration, the electrode group in the secondary battery is displaced, and if the current collector tab or the lead contacts the exterior case by chance, there is a risk of short circuit of the secondary battery.

[0004] [[ID=

ID=19

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] The problem that this invention aims to solve is to provide a highly safe secondary battery with excellent vibration resistance. [Means for solving the problem]

[0007] To achieve the above objectives, the secondary battery of the embodiment includes a positive electrode, a negative electrode, and a separator, and has at least one end an electrode group having multiple layers of current-collecting tabs led out from the positive electrode and the negative electrode, an outer case housing the electrode group, and an insulating cover covering the current-collecting tabs. The current-collecting tab has a first clamping portion whose tip is clamped by the insulating cover, and an outgoing portion provided from the first clamping portion toward the one end of the electrode group and covered by the insulating cover. [Brief explanation of the drawing]

[0008] [Figure 1] A schematic perspective view showing a secondary battery according to the first embodiment. [Figure 2] A schematic perspective view showing a secondary battery according to the first embodiment, disassembled into its individual components. [Figure 3] A schematic perspective view showing the area around the electrode group used in the secondary battery according to the first embodiment. [Figure 4] A cross-sectional view of the section along line II in Figure 3, viewed from the direction of the arrow. [Figure 5] A first perspective view schematically showing an insulating cover used in a secondary battery according to the first embodiment, viewed from the current collector tab 70. [Figure 6] A second perspective view schematically shows the insulating cover used in the secondary battery according to the first embodiment, viewed from the opposite side of Figure 5. [Figure 7] A first front view schematically showing the area around the electrode group used in the secondary battery according to the first embodiment. [Figure 8] A schematic perspective view showing a modified example 1 of the insulating cover used in a secondary battery according to the first embodiment. [Figure 9]A cross-sectional view of the cross-section along line II in Figure 3, viewed from the direction of the arrow, when using the insulating cover of Modification 1. [Figure 10] A schematic perspective view showing a modified example 2 of the insulating cover used in a secondary battery according to the first embodiment. [Figure 11] A cross-sectional view of the section along line II in Figure 3, viewed from the direction of the arrow, when using the insulating cover of Modification 2. [Figure 12] A second front view schematically showing the area around the electrode group used in the secondary battery according to the first embodiment. [Modes for carrying out the invention]

[0009] The secondary battery of this embodiment will be described below with reference to the drawings.

[0010] (First Embodiment) A 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 according to the first embodiment, and Figure 2 is a schematic perspective view showing the secondary battery 1 according to the first embodiment disassembled into its components. As shown in Figures 1 and 2, the secondary battery 1 comprises an outer casing 3 and an electrode group 5. The outer casing 3 is, for example, cylindrical in shape with side walls and a bottom wall. The outer casing 3 has an internal cavity, and an opening 9 is provided at the top. For example, a lid member 7 is placed in the opening 9, and the outer casing 3 and the lid member 7 are made of metal such as aluminum, aluminum alloy, iron, copper, or stainless steel. The secondary battery 1 only needs to have an outer casing 3 and an electrode group 5, and as in this embodiment, the bottom wall and opening 9 are not limited to a rectangular shape, and the outer casing 3 is not limited to a cylindrical shape.

[0011] The electrode group 5 is housed in the internal cavity of the outer case 3. The electrode group 5 is manufactured, for example, by winding a separator (not shown) between the positive electrode 13 and the negative electrode 15 around an axis, and then press-molding the entire assembly into a flattened shape. The positive electrode 13 has a positive electrode current collector 13a and a positive electrode active material carrying portion (not shown) supported on one or both sides of the positive electrode current collector 13a. Here, the positive electrode current collector 13a is a metal foil. The positive electrode current collector 13a has a positive electrode current collector tab 70a as an uncoated portion of the positive electrode active material carrying portion. On the other hand, the negative electrode 15 has a negative electrode current collector 15a and a negative electrode active material carrying portion (not shown) supported on one or both sides of the negative electrode current collector 15a. Here, the negative electrode current collector 15a is a metal foil. The negative electrode current collector 15a includes a negative electrode current collector tab 70b as an uncoated portion of the negative electrode active material carrying area. Hereinafter, the positive electrode current collector tab 70a and the negative electrode current collector tab 70b may be collectively referred to as the current collector tab 70. The electrode group 5 may be a stack structure manufactured by alternately stacking a plurality of positive electrodes 13 and a plurality of negative electrodes 15, with a separator provided between the positive electrodes 13 and the negative electrodes 15, and is not limited to a wound structure or a stack structure. When using an electrode group 5 with a stack structure instead of a wound structure, the connection structure with the outer case 3 should be modified as appropriate.

[0012] In this embodiment, the electrode group 5 is a wound body, and at least one end of the electrode group 5 is provided with multiple layers of current-collecting tabs 70, which are led out from the positive electrode 13 and the negative electrode 15. In this embodiment, the positive electrode current-collecting tab 70a is led out in the opposite direction to the lead-out direction of the negative electrode current-collecting tab 70b, and current-collecting tabs 70 are provided at both ends of the electrode group 5 in the winding axis direction, and are led out in a direction perpendicular to the direction (Z direction) in which the electrode group 5 is housed in the outer case 3. However, the lead-out directions of the positive electrode current-collecting tab 70a and the negative electrode current-collecting tab 70b are not limited to these. For example, both current-collecting tabs 70 may be led out in the same direction, and a current-collecting tab 70 may be provided at one end of the electrode group 5.

[0013] When using the wound electrode group 5 as in this embodiment and provided with the current collecting tabs 70 wound around both ends in the winding axis direction, it is preferable that the tips of the current collecting tabs 70 are sandwiched by two or more conductive members 16. Here, "sandwiching" means that the conductive members 16 bundle and integrate multiple layers of the current collecting tabs 70, and it is sufficient that at least a part of the conductive members 16 is in contact with one surface and the other surface of the current collecting tabs 70. Thereby, for example, as a means for increasing the capacity of the secondary battery 1, even when increasing the weight of the electrode group 5, the current collecting tabs 70 can be stably sandwiched by the conductive members 16. Here, the case of increasing the weight of the electrode group 5 refers to the case of increasing the dimensions of the electrode group or increasing the number of windings of the electrode in order to increase the mass of the electrode active material. The number of the conductive members 16 arranged 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 at both ends of the electrode group 5 is sandwiched by one or more conductive members 16.

[0014] The positive electrode 13 is manufactured by applying a slurry containing a positive electrode active material to a positive electrode current collector 13a made of aluminum foil, aluminum alloy foil, or the like. Examples of the positive electrode active material include, but are not limited to, oxides, sulfides, and their polymers that can occlude and release lithium ions. Preferred positive electrode active materials include lithium manganese composite oxides, lithium nickel composite oxides, lithium cobalt composite oxides, and lithium iron phosphate.

[0015] The negative electrode 15 is manufactured by applying a slurry containing a negative electrode active material to a negative electrode current collector 15a made of aluminum foil, aluminum alloy foil, or copper foil. Examples of the negative electrode active material include, but are not limited to, metal oxides, metal sulfides, metal nitrides, and carbon materials that can occlude and release lithium ions. Preferred negative electrode active materials include titanium oxides, lithium titanium oxides, niobium titanium oxides, niobium oxides, tungsten oxides, amorphous tin oxides, tin silicon oxides, silicon oxides, and silicon.

[0016] Inside the outer case 3, the electrode group 5 is impregnated with an electrolytic solution (not shown). The electrolytic solution is injected, for example, from a liquid injection port 17 provided in the lid member 7, and the liquid injection port 17 is sealed with a sealing plate 19 after the injection of the electrolytic solution. As the electrolytic solution, a non-aqueous electrolytic solution prepared by dissolving an electrolyte (for example, a lithium salt) in a non-aqueous solvent is used. The non-aqueous solvent may be used alone or in combination of two or more kinds.

[0017] On the surface of the lid member 7, a gas discharge valve 21 is formed together with the liquid injection port 17. Note that the liquid injection port 17 and the gas discharge valve 21 may not be provided on the lid member 7. Further, on the surface of the lid member 7, for example, a pair of external terminals 23 are attached, and the external terminals 23 are formed of a conductive material such as metal. The external terminals 23 are disposed in close contact with the lid member 7 via an insulating gasket 29, and are further connected to leads 31 respectively.

[0018] The electrode group 5 is preferably electrically connected to the external terminal 23 by joining the lead 31 to the conductive member 16 sandwiching the current collecting tab 70. When the lead 31 is joined to the conductive member 16, breakage of the current collecting tab 70 during joining can be suppressed as compared with the case where the lead 31 is directly joined to the current collecting tab 70.

[0019] Furthermore, an internal insulating member 33 may be provided between the lid member 7 and the lead 31, and the lid member 7 and the lead 31 are electrically insulated.

[0020] Also in this embodiment, the current collecting tab 70 is provided between the current collecting tab 70 and the outer case 3, and is electrically insulated from the outer case 3 by an insulating cover 34 covering the current collecting tab 70. The insulating cover 34 is fixed to the electrode group 5 by an insulating tape 36. A terminal insulator 35 may be provided between the external terminal 23 and the lid member 7, and the external terminal 23 and the lid member 7 are electrically insulated.

[0021] The insulating cover 34 covers the current collector tab 70, and the surrounding structure of the electrode group 5 when the current collector tab 70 is covered by the insulating cover 34 will be explained with reference to Figure 3. Furthermore, the structure in which the current collector tab 70 is covered by the insulating cover 34 will be explained with reference to Figure 4. Figure 3 is a schematic perspective view showing the area around the electrode group 5 used in the secondary battery 1 according to the first embodiment, and Figure 4 is a cross-sectional view of the cross section along line II in Figure 3, viewed from the direction of the arrow.

[0022] As shown in Figures 3 and 4, the insulating cover 34 covers the current collector tab 70 and clamps the tip of the current collector tab 70. Here, the portion of the current collector tab 70 clamped by the insulating cover 34 is referred to as the first clamping portion 80. The tip of the current collector tab 70 is region R in Figure 4, which is a region where a part of the insulating cover 34 is provided in parallel in the X direction in Figure 4. Clamping here means that a part of the tip of the current collector tab 70 (region R) is in contact with a part of the insulating cover 34 provided in parallel in the X direction.

[0023] Furthermore, in the current collector tab 70, the portion provided from the first clamping portion 80 toward one end (wire Q) of the electrode group 5 (the portion provided in region S) is defined as the lead portion 82. As shown in Figure 4, the lead portion 82 is covered by an insulating cover 34, similar to the first clamping portion 80. Here, one end of the electrode group 5 is wire Q, which is the boundary between the positive electrode 13 and the negative electrode 15 and the current collector tab 70 provided by leading from the positive electrode 13 and the negative electrode 15.

[0024] In the case of electrode group 5 of this embodiment, which has wound current-collecting tabs 70 at both ends in the direction of its winding axis, as shown in Figure 4, the first clamping portion 80 and the lead portion 82 of the current-collecting tab 70 are provided at the innermost circumference 704 and the outermost circumference 702 of the winding of the current-collecting tab 70. Therefore, the insulating cover 34 covers both the innermost circumference 704 and the outermost circumference 702 of the current-collecting tab 70.

[0025] In the secondary battery 1 of this embodiment, the current collector tab 70 has a first clamping portion 80 that is held by the insulating cover 34 and an outlet portion 82 that is covered by the insulating cover 34. As a result, even if the secondary battery 1 vibrates due to vibrations during vehicle operation, for example, the current collector tab 70 has a first clamping portion 80 that is held by the insulating cover 34 and an outlet portion 82 that is covered by the insulating cover 34, so the displacement of the current collector tab 70 can be suppressed by the insulating cover 34. Since the displacement of the current collector tab 70 can be suppressed by the insulating cover 34, a short circuit of the secondary battery 1 due to the current collector tab 70 coming into contact with the outer casing 3 can be prevented.

[0026] The structure of the insulating cover 34 will be described with reference to Figures 5 and 6. Figure 5 is a first perspective view schematically showing the insulating cover 34 used in the secondary battery 1 according to the first embodiment, viewed from the current collection tab 70 side, and Figure 6 is a second perspective view schematically showing the insulating cover 34 used in the secondary battery 1 according to the first embodiment, viewed from the opposite side of Figure 5.

[0027] As shown in Figures 5 and 6, the insulating cover 34 has a U-shaped member 40 having a pair of side walls, a rear member 42 connected to the U-shaped member 40, and a bottom member 44 extending from the U-shaped member 40 and the rear member 42. As mentioned above, the insulating cover 34 covers the current collector tab 70, but the current collector tab 70 only needs to be electrically insulated from the outer case 3, and the insulating cover 34 does not need to have a bottom member 44. Furthermore, the insulating cover 34 has a projection 60 protruding from the rear member 42.

[0028] The U-shaped member 40 and the base member 44 of the insulating cover 34 are provided in contact with the outermost periphery 702 of the current collection tab 70. Here, "contact" means that at least a portion of the U-shaped member 40 and the base member 44 is in contact with the outermost periphery 702 of the current collection tab 70. The projection 60 of the insulating cover 34 is inserted into the innermost periphery 704 of the current collection tab 70 and is positioned in contact with the innermost periphery 704. Here, "contact" means that at least a portion of the projection 60 is in contact with the innermost periphery 704 of the current collection tab 70.

[0029] The current collector tab 70 has a first clamping portion 80 and an outlet portion 82 covered by an insulating cover 34. The arrangement of the first clamping portion 80 and the outlet portion 82 will be explained with reference to Figure 7. Figure 7 is a first front view schematically showing the area around the electrode group 5 used in the secondary battery 1 according to the first embodiment. As shown in Figure 7, it is preferable that the first clamping portion 80 and the outlet portion 82 of the current collector tab 70 are provided in a region with a height of 0.5A from the bottom to the top of the electrode group 5, with respect to the height A in the housing direction (Z) of the electrode group 5. Here, it is sufficient that at least a part of the first clamping portion 80 and the outlet portion 82 of the current collector tab 70 are provided in a region with a height of 0.5A from the bottom to the top of the electrode group 5. This is because the region of 0.5A extending from the bottom to the top of electrode group 5 is more susceptible to displacement of the current collection tab 70 due to vibrations of the secondary battery 1 than the region of 0.5A to A extending from the bottom to the top of electrode group 5.

[0030] The insulating cover 34 of this embodiment will be described in more detail with reference to Figure 4 again. As shown in Figure 4, in the insulating cover 34, the angle p(p1·p2·p3·p4) formed by the first contact portion 800 with the first clamping portion 80 of the current collector tab 70 and the second contact portion 820 with the lead portion 82 is preferably 105° or more and 165° or less. Here, the first contact portion 800 is the portion of the insulating cover 34 that clamps the first clamping portion 80 of the current collector tab 70, and the second contact portion 820 is the portion of the insulating cover 34 that covers the lead portion 82 of the current collector tab 70. If the angle p(p1·p2·p3·p4) is 105° or more, the outermost 702 and innermost 704 portions of the current-collecting tab 70 at one end (wire Q) of the electrode group 5 will be pulled by the insulating cover 34 that clamps the first clamping portion 80 of the current-collecting tab 70, and this will prevent breakage. Also, if the angle p(p1·p2·p3·p4) is 165° or less, the angle formed by the projection 60 with respect to the insertion direction of the current-collecting tab 70 into the innermost 704 will be sharp, making it easier for the projection 60 to be inserted into the innermost 704 of the current-collecting tab 70.

[0031] Furthermore, in the insulating cover 34, it is more preferable that the angle p(p1·p2·p3·p4) formed by the first contact portion 800 with the first clamping portion 80 of the current collector tab 70 and the second contact portion 820 with the lead portion 82 is 120° or more and 150° or less. By having an angle p(p1·p2·p3·p4) of 120° or more, the current collector tab 70 at the outermost periphery 702 and the innermost periphery 704 at one end (wire Q) of the electrode group 5 is pulled by the insulating cover 34 that clamps the first clamping portion 80 of the current collector tab 70, and this prevents it from breaking. Furthermore, because the angle p(p1·p2·p3·p4) is 150° or less, the projection 60 of the insulating cover 34 is easily inserted into the innermost circumference 704 of the current collector tab 70, and contact between the insulating cover 34 and the lead-out portion 82 of the current collector tab 70 is facilitated.

[0032] As shown in Figure 4, the insulating cover 34 has multiple first contact points 800 with the first clamping portion 80 of the current collector tab 70 and multiple second contact points 820 with the outlet portion 82. As a result, multiple angles p(p1·p2·p3·p4) are formed by the first contact points 800 with the first clamping portion 80 and the second contact points 820 with the outlet portion 82. It is preferable that these angles p(p1·p2·p3·p4) are equal. By having equal angles p(p1·p2·p3·p4), for example, even if the secondary battery 1 vibrates due to vibrations during vehicle operation, the displacement of the current collector tab 70 can be suppressed evenly at each of the first contact points 800 and each of the second contact points 820. In the insulating cover 34 of Figure 8, angles p(p1·p2·p3·p4) are all equal at 135°.

[0033] The angles p(p1·p2·p3·p4) formed by the first contact portion 800 with the first clamping portion 80 and the second contact portion 820 with the lead-out portion 82 of the current collector tab 70 may be different. A modified example 1 of the insulating cover 34 of this embodiment will be described with reference to Figures 8 and 9. Figure 8 is a schematic perspective view showing a modified example 1 of the insulating cover 34 used in the secondary battery 1 according to the first embodiment, and Figure 9 is a cross-sectional view of the cross section along line II in Figure 3, viewed from the direction of the arrow, when the insulating cover 34 of modified example 1 is used. The difference between the insulating cover 34 of modified example 1 and the insulating cover 34 shown in Figures 5 and 6 is the angles p(p1·p2·p3·p4) formed by the first contact portion 800 with the first clamping portion 80 and the second contact portion 820 with the lead-out portion 82.

[0034] In the insulating cover 34 of the modified example 1, the angles p1 and p4 formed by the first contact portion 800 and the second contact portion 820 with the outermost periphery 702 of the current collector tab 70 are larger than the angles p2 and p3 formed by the first contact portion 800 and the second contact portion 820 with the innermost periphery 704 of the current collector tab 70. As a result, at one end (wire Q) of the electrode group 5, the outermost periphery 70 of the current collector tab 70 is less likely to be pulled by the insulating cover 34 that grips the first clamping portion 80 of the current collector tab 70 than at the innermost periphery 704, thus preventing the outermost periphery 702 of the current collector tab 70 from breaking. In the insulating cover 34 of Figure 9, angles p1 and p4 are 135°, and angles p2 and p3 are 120°.

[0035] A modified example 2 of the insulating cover 34 of this embodiment will be described with reference to Figures 10 and 11. Figure 10 is a schematic perspective view showing a modified example 2 of the insulating cover 34 used in the secondary battery 1 according to the first embodiment, and Figure 11 is a cross-sectional view taken from the direction of the arrow, showing the cross section along line II in Figure 3 when the insulating cover 34 of modified example 2 is used. The difference between the insulating cover 34 of modified example 2 and the insulating cover 34 shown in Figures 5 and 6 is the angle p(p1·p2·p3·p4) formed by the first contact portion 800 with the first clamping portion 80 and the second contact portion 820 with the outlet portion 820.

[0036] In the insulating cover 34 of the modified example 2, the angles p2 and p3 formed by the first contact portion 800 and the second contact portion 820 with the innermost circumference 704 of the current collector tab 70 are larger than the angles p1 and p4 formed by the first contact portion 800 and the second contact portion 820 with the outermost circumference 702 of the current collector tab 70. As a result, at one end (wire Q) of the electrode group 5, the innermost circumference 704 of the current collector tab 70 is less likely to be pulled by the insulating cover 34 that grips the first clamping portion 80 of the current collector tab 70 than the outermost circumference 702, thus preventing the innermost circumference 704 of the current collector tab 70 from breaking. Furthermore, because angles p2 and p3 are larger than angles p1 and p4, the angle formed by the projection 60 becomes sharper, making it easier for the projection 60 to be inserted into the innermost circumference 704 of the current collector tab 70. In the insulating cover 34 of Figure 11, angles p1 and p4 are 120°, and angles p2 and p3 are 135°.

[0037] In Modification 1 and Modification 2, angles p1 and p4 are equal, and angles p2 and p3 are equal, but each angle p(p1·p2·p3·p4) may be different.

[0038] Furthermore, in this embodiment, it is preferable that at least a portion of the first clamping portion 80 and the lead portion 82 of the current collector tab 70 are provided in a region of 0.5A extending upward from the bottom of the electrode group 5. In this case, it is even more preferable that the lead 31 is joined to the conductive member 16 to which the tip of the current collector tab 70 is clamped. Here, the portion of the tip of the current collector tab 70 that is clamped by the conductive member 16 is referred to as the second clamping portion 90. The arrangement position of the conductive member 16 to which the lead 31 is joined will be described with reference to Figure 12.

[0039] Figure 12 is a second front view schematicly showing the area around the electrode group 5 used in the secondary battery 1 according to the first embodiment. As shown in Figure 12, it is preferable that at least a part of the second clamping portion 90 of the current collecting tab 70 is provided in a region from 0.5A to A, from the bottom to the top of the electrode group 5, with respect to the height A in the housing direction (Z) of the electrode group 5. As mentioned above, since the lead 31 is electrically connected not only to the conductive member 16 but also to the external terminal 23, it is preferable that the position where the lead 31 is provided is close to the external terminal 23 from the viewpoint of current carrying characteristics. Therefore, it is preferable that the conductive member 16 is provided in a region from a height of 0.5A to A, from the bottom 66 to the top 68 of the electrode group 5, with respect to the height A. This makes it possible to extract electrical energy from the electrode group 5 via the lead 31 at a position close to the external terminal 23, and to obtain high current carrying characteristics. However, the lead 31 may be directly electrically connected to the current collector tab 70 without the conductive member 16, and even when the lead 31 and the current collector tab 70 are directly connected, it is preferable that the connection be made in the region from 0.5A to A from the bottom to the top of the electrode group 5.

[0040] As a result, even if the secondary battery 1 vibrates, the displacement of the current collector tab 70 can be suppressed by the conductive member 16 and lead 31 in the region from 0.5A to A extending from the bottom to the top of the electrode group 5. Furthermore, by using the insulating cover 34 of this embodiment, the displacement of the current collector tab 70 can also be suppressed by the insulating cover 34 in the region from 0.5A extending from the bottom to the top of the electrode group 5, that is, in the region where displacement of the current collector tab 70 is likely to occur. As a result, the displacement of the current collector tab 70 due to vibration of the secondary battery 1 can be suppressed in the entire region from the bottom to the top of the electrode group 5.

[0041] Furthermore, even if the weight of the electrode group 5 increases by increasing the dimensions of the electrode group 5 or increasing the number of turns of the electrode group 5, the displacement of the current collecting tab 70 can be suppressed by the conductive member 16 and the insulating cover 34.

[0042] According to the secondary battery 1 of at least one embodiment described above, the current collector tab 70 has a first clamping portion 80 that is clamped by the insulating cover 34 and an outlet portion 82 that is covered by the insulating cover 34. As a result, even if the secondary battery 1 vibrates due to vibrations during vehicle operation, for example, the current collector tab 70 has a first clamping portion 80 that is clamped by the insulating cover 34 and an outlet portion 82 that is covered by the insulating cover 34, so the displacement of the current collector tab 70 can be suppressed by the insulating cover 34. Since the displacement of the current collector tab 70 can be suppressed by the insulating cover 34, a short circuit of the secondary battery 1 due to the current collector tab 70 coming into contact with the outer case 3 can be prevented, and a highly safe secondary battery 1 with excellent vibration resistance can be provided.

[0043] Furthermore, as the capacity of the secondary battery 1 increases, even if the weight of the electrode group 5 increases by increasing the size of the electrode group 5 or increasing the number of turns of the electrode group 5, the displacement of the current collector tab 70 can be suppressed not only by the conductive member 16 but also by the insulating cover 34, thereby suppressing the displacement of the current collector tab 70. This prevents short circuits of the secondary battery 1 caused by the current collector tab 70 coming into contact with the outer case 3, and provides a highly safe secondary battery 1 with excellent vibration resistance.

[0044] 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]

[0045] 1...Secondary battery, 3...Outer case, 5...Electrode group, 7...Lid member, 9...Opening, 13...Positive electrode, 13a...Positive electrode current collector, 15...Negative electrode, 15a...Negative electrode current collector, 16...Conductive member, 16a...Positive electrode conductive member, 16b...Negative electrode conductive member, 17...Filling port, 19...Sealing plate, 21...Gas release valve, 23...External terminal, 23a...Positive electrode external terminal, 23b...Negative electrode external terminal, 29...Insulating gasket, 31...Lead, 31a...Positive electrode lead, 31b...negative lead, 33...internal insulating member, 34...insulating cover, 35...terminal insulator, 36...insulating tape, 40...U-shaped member, 42...back member, 44...bottom member, 60...protrusion, 70...current collector tab, 70a...positive current collector tab, 70b...negative current collector tab, 80...first clamping part, 82...outlet part, 90...second clamping part, 702...outermost part, 704...innermost part, 800...first contact part, 820...second contact part.

Claims

1. An electrode group comprising a positive electrode, a negative electrode, and a separator, having at least one end having multiple layers of current-collecting tabs derived from the positive electrode and the negative electrode, An outer case for housing the aforementioned electrode group, The system comprises an insulating cover that covers the current collection tab, The current collector tab has a first clamping portion whose tip is clamped by the insulating cover, A secondary battery having a lead-out portion provided from the first clamping portion toward one end of the electrode group and covered by the insulating cover.

2. The electrode group has wound current-collecting tabs at both ends in the direction of its winding axis, The secondary battery according to claim 1, wherein the first clamping portion and the discharge portion are provided on the innermost and outermost circumferences of the winding of the current collecting tab.

3. The secondary battery according to claim 2, wherein the insulating cover has a projection disposed on the innermost circumference of the winding structure of the current collector tab.

4. The current collection tab is led out in a direction perpendicular to the direction in which the electrode group is housed in the outer casing, At least a portion of the first clamping portion and the lead portion of the current collection tab is With respect to the height A of the electrode group in the direction in which the electrode group is housed in the outer case, The secondary battery according to claim 1, wherein the electrode group is provided in a region with a height of 0.5A extending upward from the bottom to the top.

5. The secondary battery according to claim 1, wherein the angle between the first contact portion of the insulating cover with the first clamping portion of the current collection tab and the second contact portion with the current outlet portion is 105° or more and 165° or less.

6. The secondary battery according to claim 1, wherein the angle between the first contact portion of the insulating cover with the first clamping portion of the current collection tab and the second contact portion with the current outlet portion is 120° or more and 150° or less.

7. The secondary battery according to claim 5, wherein the insulating cover has a plurality of first contact portions with the first clamping portion of the current collector tab and a plurality of second contact portions with the outlet portion, and the angles of the first contact portions with the first clamping portion of the current collector tab and the second contact portions with the outlet portion are equal.

8. The current collector tab has a second clamping portion at its tip that is clamped between it and the insulating cover by a conductive member, The secondary battery according to claim 4, wherein at least a portion of the second clamping portion of the conductive member is provided in a region from a height of 0.5A to A extending upward from the bottom of the electrode group.

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