Secondary battery

Abstract

A secondary battery according to an embodiment of the present invention comprises: an electrode group including a positive electrode and a negative electrode, and having a plurality of layers of collector tabs led out from the positive electrode and the negative electrode at least at one end; and an exterior case for housing the electrode group. The collector tab includes: a first holding part having a tip that is sandwiched and held by an insulating cover; and a lead-out part provided from the first holding part toward the one end of the electrode group and covered with the insulating cover.

Description

Secondary battery

[0001] An embodiment of the present invention relates to a secondary battery.

[0002] In recent years, as a typical power source used in electric vehicles, hybrid vehicles, electric motorcycles, forklifts, etc., secondary batteries such as lead-acid batteries and nickel-metal hydride batteries are known. Recently, lithium-ion secondary batteries with high energy density have been actively developed for adoption, and further development has been carried out while considering long life, safety, etc.

[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 collecting tab led out from the electrode group, and leads of positive and negative electrodes joined to this current collecting 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 driving. Along with this vibration, the electrode group in the secondary battery is displaced, and if the current collecting tab or the lead contacts the exterior case by chance, a short circuit of the secondary battery may occur.

[0004] Also, secondary batteries are generally required to have a high capacity. As means for increasing the capacity, in order to increase the mass of the electrode active material, it is conceivable to increase the dimensions of the electrode group or increase the number of windings of the electrode. However, with such means, the electrode group becomes heavy. The above-described vibration increases according to the weight of the electrode group, and there is a possibility that a short circuit of the secondary battery may occur along with the displacement of the electrode group.

[0005] Japanese Patent Application Laid-Open No. 2015-92507

[0006] The problem of the embodiment of the present invention is to provide a highly safe secondary battery with excellent vibration resistance.

[0007] To achieve the above objectives, the secondary battery of the embodiment includes an electrode group having a positive electrode and a negative electrode, and at least one end having a plurality of 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 output portion provided between the first clamping portion and the one end of the electrode group and covered by the insulating cover.

[0008] Figure 1 is a schematic perspective view showing a secondary battery according to the first embodiment. Figure 2 is a schematic exploded perspective view showing the secondary battery according to the first embodiment disassembled into its components. Figure 3 is a schematic perspective view showing the area around the electrode group used in the secondary battery according to the first embodiment. Figure 4 is a cross-sectional view of the section along line I-I in Figure 3, viewed from the direction of the arrow. Figure 5 is a first perspective view showing the insulating cover used in the secondary battery according to the first embodiment from the viewpoint of the current collector tab 70. Figure 6 is a second perspective view showing the insulating cover used in the secondary battery according to the first embodiment from the viewpoint on the opposite side of Figure 5. Figure 7 is a first front view showing the area around the electrode group used in the secondary battery according to the first embodiment. Figure 8 is a schematic perspective view showing modification 1 of the insulating cover used in the secondary battery according to the first embodiment. Figure 9 is a cross-sectional view of the section along line I-I in Figure 3, viewed from the direction of the arrow, when using the insulating cover of modification 1. Figure 10 is a schematic perspective view showing a modified example 2 of the insulating cover used in the secondary battery according to the first embodiment. Figure 11 is a cross-sectional view taken from the direction of the arrow, showing the cross section along line I-I in Figure 3 when using the insulating cover of modified example 2. Figure 12 is a second front view schematicly showing the area around the electrode group used in the secondary battery according to the first embodiment.

[0009] A secondary battery according to an embodiment of this invention will be described below with reference to the drawings. Note that the disclosure is merely an example, and modifications that are easily conceivable by those skilled in the art while maintaining the spirit of the invention are naturally included within the scope of this invention. Furthermore, in order to clarify the explanation, the drawings may schematically represent the width, thickness, shape, etc., of each part compared to the actual embodiment, but these are merely examples and do not limit the interpretation of this invention. In this specification and in each drawing, elements similar to those described above with respect to previously shown drawings are denoted by the same reference numerals, and detailed explanations may be appropriately simplified or omitted.

[0010] (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 according to the first embodiment, and Figure 2 is an exploded 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 case 3 and an electrode group 5. The outer case 3 is, for example, cylindrical in shape with side walls and a bottom wall. The outer case 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. The outer case 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 case 3 and an electrode group 5, and the outer case 3 is not limited to a cylindrical shape. The bottom wall and opening 9 of the outer case 3 are not limited to a rectangular shape and may be other shapes.

[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 positive electrode 13, a negative electrode 15, and a separator (not shown) sandwiched between the positive electrode 13 and the negative electrode 15 around a winding shaft C, and then press-molding the whole into a flattened shape. In other words, in this embodiment, the electrode group 5 has a wound structure. 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.

[0012] 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 has a negative electrode current collecting tab 70b as an uncoated portion of the negative electrode active material carrying portion. Hereinafter, the positive electrode current collecting tab 70a and the negative electrode current collecting tab 70b may be collectively referred to as the current collecting tab 70. The electrode group 5 is not limited to a wound structure, but may also 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. When using an electrode group 5 with a stack structure, the connection structure with the outer case 3 is changed as appropriate. Furthermore, the electrode group 5 is not limited to a wound structure or a stack structure.

[0013] 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 leading from the positive electrode 13 and the negative electrode 15. In this embodiment, a positive electrode current-collecting tab 70a is provided at one end of the electrode group 5 in the direction of the winding axis C, and a negative electrode current-collecting tab 70b is provided at the other end in the direction of the winding axis C. The positive electrode current-collecting tab 70a and the negative electrode current-collecting tab 70b 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. Furthermore, 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. Note that 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 70a and 70b may be led out in the same direction, and the current-collecting tabs 70a and 70b may be provided at one end of the electrode group 5.

[0014] In this embodiment, when a wound electrode group 5 is used and current-collecting tabs 70 wound at both ends in the direction of the winding axis C, it is preferable that the tips of the current-collecting tabs 70 are clamped by two or more conductive members 16. Here, clamping means that the conductive member 16 bundles and integrates multiple layers of current-collecting tabs 70, and it is sufficient that at least a part of the conductive member 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 conductive member 16, for example, even 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 increasing the size of the electrode group or increasing the number of windings of the electrodes in order to increase the mass of the electrode active material. The number of conductive 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 at both ends of the electrode group 5 is sandwiched by one or more conductive members 16.

[0015] 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 or aluminum alloy foil. Examples of positive electrode active materials include oxides, sulfides, and polymers thereof that can intercept and deintercept lithium ions, but are not limited to these. Preferred positive electrode active materials include lithium manganese composite oxide, lithium nickel composite oxide, lithium cobalt composite oxide, and lithium iron phosphate.

[0016] 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 negative electrode active materials include, but are not limited to, metal oxides, metal sulfides, metal nitrides, and carbon materials that can intercept and deintercept lithium ions. Preferred negative electrode active materials include titanium oxide, lithium titanium oxide, niobium titanium oxide, niobium oxide, tungsten oxide, amorphous tin oxide, tin silicon oxide, silicon oxide, and silicon.

[0017] Inside the outer casing 3, the electrode group 5 is impregnated with an electrolyte (not shown). The electrolyte is injected into the outer casing 3, for example, through an injection port 17 provided on the lid member 7. The injection port 17 is sealed with a sealing plate 19 after the electrolyte has been injected. The electrolyte used is a non-aqueous electrolyte prepared by dissolving an electrolyte (for example, a lithium salt) in a non-aqueous solvent. The non-aqueous solvent may be used alone or in a mixture of two or more types.

[0018] A gas discharge valve 21 is formed on the surface of the lid member 7 along with the liquid injection port 17. Note that the liquid injection port 17 and the gas discharge valve 21 do not necessarily have to be provided on the lid member 7. Furthermore, for example, a pair of external terminals 23 are attached to the surface of the lid member 7. The external terminals 23 are made of a conductive material such as metal. The external terminals 23 are arranged in close contact with the lid member 7 via an insulating gasket 29 and are further connected to the leads 31.

[0019] Preferably, the electrode group 5 is electrically connected to the external terminal 23 by joining the lead 31 to the conductive member 16 that holds the current collecting tab 70. When the lead 31 is joined to the conductive member 16, compared to when the lead 31 is directly joined to the current collecting tab 70, the tearing of the current collecting tab 70 during joining can be suppressed. An internal insulating member 33 may be provided between the cover member 7 and the lead 31, and the cover member 7 and the lead 31 are electrically insulated by the internal insulating member 33. Furthermore, a terminal insulator 35 may be provided between the external terminal 23 and the cover member 7, and the external terminal 23 and the cover member 7 are electrically insulated by the terminal insulator 35.

[0020] In this embodiment, an insulating cover 34 is provided between the current collector tab 70 and the outer casing 3, covering the current collector tab 70. The current collector tab 70 is electrically insulated from the outer casing 3 by the insulating cover 34. The insulating cover 34 is fixed to the electrode group 5 by insulating tape 36.

[0021] The surrounding structure of the electrode group 5 when the current collector tab 70 is covered by the insulating cover 34 will be described with reference to Figure 3. The structure in which the current collector tab 70 is covered by the insulating cover 34 will also be described 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 I-I 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 the region R in Figure 4, which is the 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-out portion 82. As shown in Figure 4, the lead-out 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 C, as shown in Figure 4, the first clamping portion 80 and the lead portion 82 of the current-collecting tab 70 are provided between 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 collection 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. Therefore, even if the secondary battery 1 vibrates due to vibrations during vehicle operation, for example, the displacement of the current collection tab 70 can be suppressed by the insulating cover 34. This prevents the secondary battery 1 from short-circuiting due to the current collection tab 70 coming into contact with the outer casing 3.

[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 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 back member 42 connected to the U-shaped member 40, and a bottom member 44 extending from the U-shaped member 40 and the back member 42. Furthermore, the insulating cover 34 has a projection 60 protruding from the back 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. The bottom member 44 of the insulating cover 34 is optional.

[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 portion 66 to the top portion 68 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 portion 66 to the top portion 68 of the electrode group 5. This is because the region of 0.5A extending from the bottom 66 to the top 68 of the electrode group 5 is more susceptible to displacement of the current collecting tab 70 due to vibrations of the secondary battery 1 than the region of 0.5A to A extending from the bottom 66 to the top 68 of the 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 that abuts the first clamping portion 80 of the current collection tab 70 and the second contact portion 820 that abuts 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 collection 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 collection tab 70. If the angle p(p1, p2, p3, p4) is 105° or more, the current collector tabs 70 at the outermost 702 and innermost 704 of 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 collector tab 70, and this will prevent them from breaking. 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 collector tab 70 into the innermost 704 becomes sharp, making it easier for the projection 60 to be inserted into the innermost 704 of the current collector tab 70.

[0031] 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-out 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 702 and innermost 704 of one end (wire Q) of the electrode group 5 is not pulled by the insulating cover 34 that clamps the first clamping portion 80 of the current collector tab 70, and this does not cause it to break. Also, by having an angle p(p1, p2, p3, p4) of 150° or less, the projection 60 of the insulating cover 34 is more easily inserted into the innermost 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 easier.

[0032] As shown in Figure 4, the insulating cover 34 has multiple first contact portions 800 with the first clamping portion 80 of the current collection tab 70 and multiple second contact portions 820 with the outlet portion 82. As a result, multiple angles p(p1, p2, p3, p4) are formed by the first contact portions 800 with the first clamping portion 80 and the second contact portions 820 with the outlet portion 82. It is preferable that these angles p(p1, p2, p3, p4) are all 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 collection tab 70 can be suppressed evenly at each of the first contact portions 800 and each of the second contact portions 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 that abuts the first clamping portion 80 of the current collection tab 70 and the second contact portion 820 that abuts the lead-out portion 82 may be different. Modification 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 Modification 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 I-I in Figure 3 when the insulating cover 34 of Modification 1 is used, viewed from the direction of the arrow. The difference between the insulating cover 34 of Modification 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 and the second contact portion 820.

[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 that abut against the outermost circumference 702 of the current collector tab 70 are greater than the angles p2 and p3 formed by the first contact portion 800 and the second contact portion 820 that abut against the innermost circumference 704 of the current collector tab 70. As a result, the pulling force exerted by the insulating cover 34 gripping the first clamping portion 80 of the current collector tab 70 is suppressed at the outermost circumference 702 of the current collector tab 70 at one end (wire Q) of the electrode group 5 compared to the pulling force exerted at the innermost circumference 704, thereby suppressing the breakage of the outermost circumference 702 of the current collector tab 70. In one example, in the insulating cover 34 of Figure 9, angles p1 and p4 are 135°, and angles p2 and p3 are 120°.

[0035] A second modification 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 second modification 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, along the line I-I in Figure 3 when the insulating cover 34 of the second modification is used. The difference between the insulating cover 34 of the second modification 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 that abuts the first clamping portion 80 and the second contact portion 820 that abuts the outlet portion 82.

[0036] In the insulating cover 34 of the modified example 2, the angles p2 and p3 formed by the first contact portion 800 that abuts the first clamping portion 80 on the side of the innermost circumference 704 of the current collector tab 70 and the second contact portion 820 that abuts the innermost circumference 704 are larger than the angles p1 and p4 formed by the first contact portion 800 that abuts the first clamping portion 80 on the side of the outermost circumference 702 of the current collector tab 70 and the second contact portion 820 that abuts the outermost circumference 702. As a result, at the innermost circumference 704 of the current collector tab 70 at one end (wire Q) of the electrode group 5, the pulling force by the insulating cover 34 that clamps the first clamping portion 80 of the current collector tab 70 is suppressed more than at the outermost circumference 702, thus suppressing the breakage of the innermost circumference 704 of the current collector tab 70. 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 one example, in the insulating cover 34 of Figure 11, angles p1 and p4 are 120°, and angles p2 and p3 are 135°.

[0037] In the first and second modifications, 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 from the bottom to the top 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 schematically 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 with respect to the height A in the housing direction (Z) of the electrode group 5, from the bottom portion 66 to the top portion 68 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 0.5A to A with respect to the height A, from the bottom portion 66 to the top portion 68 of the electrode group 5. 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 a region from 0.5A to A from the bottom 66 to the top 68 of the electrode group 5.

[0040] As a result, even if the secondary battery 1 vibrates, the displacement of the current collecting 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 66 to the top 68 of the electrode group 5. Furthermore, by using the insulating cover 34 of this embodiment, the displacement of the current collecting tab 70 can be suppressed by the insulating cover 34 even in the region from the bottom 66 to the top 68 of the electrode group 5, i.e., the region where displacement of the current collecting tab 70 is likely to occur. As a result, the displacement of the current collecting tab 70 due to vibration of the secondary battery 1 can be suppressed in the entire region from the bottom 66 to the top 68 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 collecting tab 70 can be suppressed not only by the conductive member 16 but also by the insulating cover 34. This prevents short circuits of the secondary battery 1 caused by the current collecting 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 implemented in various 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. For example, the electrode body is not limited to a so-called wound electrode body in which an electrode plate is wound, but a so-called laminated electrode body constructed by stacking multiple electrode plates in the thickness direction may also be applied. The forming materials, shapes, sizes, etc., of the elements constituting the secondary battery are not limited to the embodiments described above and can be changed in various ways as needed.

Claims

1. A secondary battery comprising: an electrode group including a positive electrode and a negative electrode, having at least one end having a plurality of layers of current-collecting tabs led out from the positive electrode and the negative electrode; an outer case for housing the electrode group; and an insulating cover covering the current-collecting tabs, wherein the current-collecting tabs have a first clamping portion whose tip is clamped by the insulating cover, and an outgoing portion provided between the first clamping portion and the one end of the electrode group and covered by the insulating cover.

2. The secondary battery according to claim 1, wherein the electrode group is formed by winding the positive electrode and the negative electrode around a winding shaft, the electrode group includes current collecting tabs led out from one end and the other end in the winding axis direction, and the first clamping portion and the lead portion are provided at 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 is inserted between the multiple layers of current-collecting tabs and has a projection positioned on the innermost circumference.

4. The secondary battery according to claim 1, wherein the current collecting tab is led out in a direction perpendicular to the direction in which the electrode group is housed in the outer casing, and at least a part of the first clamping portion and the leading portion of the current collecting tab is provided in a region with a height of 0.5A from the bottom to the top of the electrode group, with respect to the height A of the electrode group in the direction in which the electrode group is housed in the outer casing.

5. The secondary battery according to claim 1, wherein the insulating cover has a first contact portion that abuts against the first clamping portion of the current collector tab and a second contact portion that abuts against the outlet portion, and the angle formed by the first contact portion and the second contact portion is 105° or more and 165° or less.

6. The secondary battery according to claim 1, wherein the insulating cover has a first contact portion that abuts against the first clamping portion of the current collector tab and a second contact portion that abuts against the outlet portion, and the angle formed by the first contact portion and the second contact 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 sets of first contact portions that abut against the first clamping portion of the current collecting tab and second contact portions that abut against the outlet portion, and the angles formed by the first contact portion and the second contact portion of each set are equal.

8. The secondary battery according to claim 4, wherein 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, and when the height from the bottom to the top of the electrode group is A, at least a part of the conductive member and the second clamping portion is provided in a region from a height of 0.5A to A from the bottom to the top of the electrode group.

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