Secondary battery

Abstract

To provide a secondary battery capable of dealing with a large current.SOLUTION: A secondary battery 1 comprises: a first electrode 50 and a second electrode 60 that are wound along a predetermined direction D1. A first collector 51 of the first electrode 50 is projected along the predetermined direction D1, and includes a first projection part 51b that is not overlapped with a first active material layer 52 of the first electrode 50. A second collector 61 of the second electrode 60 is projected along an orthogonal direction D2 orthogonal to the predetermined direction D1, and includes a second projection part 61b that is not overlapped with a second active material layer 62 of the second electrode 60. A first tub 30 is electrically connected to the first projection part 51b. A second tub 40 is electrically connected to the second projection part 61b.SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to secondary batteries. [Background technology]

[0002] In the lithium secondary battery disclosed in Patent Document 1, a positive electrode current collector and a negative electrode current collector form a flat electrode body. The current collecting tab of the positive electrode current collector and the current collecting tab of the negative electrode current collector are arranged on the outermost periphery of the flat electrode body. At least one of the current collecting tab of the positive electrode current collector and the current collecting tab of the negative electrode current collector is arranged parallel to the winding direction of the flat electrode body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2007-087842 A Summary of the Invention [Problem to be solved by the invention]

[0004] In recent years, secondary batteries have become larger in capacity and current. As the current of secondary batteries increases, the amount of heat generated at the connection between the current collector and the current collecting tab and the amount of heat generated by the current collecting tab also increase. Therefore, it is desirable to increase the connection area between the current collector and the current collecting tab and the cross-sectional area of ​​the current collecting tab to reduce the amount of heat generated. In addition, it is desirable that the two current collecting tabs are separated from each other in a plan view along the thickness direction of the flat electrode body from the viewpoints of electrical insulation and reduction in the amount of heat generated.

[0005] However, in the lithium secondary battery (secondary battery) of Patent Document 1, both the current collecting tab on the positive electrode current collector and the current collecting tab on the negative electrode current collector are disposed at the outermost periphery of the flat electrode body. Therefore, when the two current collecting tabs are separated from each other, it may be impossible to ensure a sufficient connection area between the current collector and the current collecting tab. In addition, when the two current collecting tabs are disposed so as to extend parallel to each other, it may be impossible to ensure a sufficient width of the current collecting tab, and therefore, it may be impossible to ensure a sufficient cross-sectional area of ​​the current collecting tab.

[0006] The present disclosure has been made in view of the above, and has an object to provide a secondary battery capable of handling a large current. [Means for solving the problem]

[0007] The secondary battery of the present disclosure has a first electrode, a second electrode having a different potential from the first electrode, and a separator between the first electrode and the second electrode, and is provided with an electrode assembly in which the first electrode, the second electrode, and the separator are wound along a predetermined direction, a first tab electrically connected to the first electrode, and a second tab electrically connected to the second electrode, the first electrode comprising a foil-shaped first current collector and a first active material layer overlapping the first current collector and containing an active material of the first electrode, the second electrode comprising a foil-shaped second current collector and a second active material layer overlapping the second current collector and containing an active material of the second electrode, the first current collector being perpendicular to the predetermined direction in a plan view in a state where it is spread out flat. the second current collector has a first side extending along the predetermined direction and overlaps the first active material layer, and is integral with a first protruding portion that protrudes from the first side along the predetermined direction in a plan view when spread out flat and does not overlap with the first active material layer, the second current collector has a second side extending along the predetermined direction in a plan view when spread out flat and overlaps the second active material layer, and is integral with a second protruding portion that protrudes from the second side along a direction perpendicular to the predetermined direction in a plan view when spread out flat and does not overlap with the second active material layer, the first tab is electrically connected to the first protruding portion, and the second tab is electrically connected to the second protruding portion. Effect of the Invention

[0008] The secondary battery of the present disclosure can handle large currents. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a plan view of a secondary battery according to an embodiment of the present disclosure. [Diagram 2] FIG. 2 is an exploded perspective view of the secondary battery shown in FIG. [Diagram 3] FIG. 3 is a plan view of the electrode body shown in FIG. [Figure 4] FIG. 4 is a cross-sectional view of the electrode body taken along line IX-IX shown in FIG. [Diagram 5] FIG. 5 is a partial cross-sectional view of the first pole. [Figure 6] FIG. 6 is a plan view showing the first current collector in a flat laid out state. [Figure 7] FIG. 7 is a partial cross-sectional view of the second pole. [Figure 8] FIG. 8 is a plan view showing the second current collector in a flat laid out state. [Figure 9] FIG. 9 is a plan view of an electrode assembly according to a comparative example of the embodiment of the present disclosure. [Figure 10] FIG. 10 is a cross-sectional view of an electrode body of a comparative example taken along line XX shown in FIG. [Figure 11] FIG. 11 is a plan view showing a state in which the second current collector of the second electrode of the electrode assembly of the comparative example shown in FIG. 9 is spread out flat. [Figure 12] FIG. 12 is a plan view of an electrode assembly of a secondary battery according to a first modified example of an embodiment of the present disclosure. [Figure 13] FIG. 13 is a plan view showing a second current collector in a state where it is spread out flat in a secondary battery according to a second modified example of the embodiment of the present disclosure. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the embodiments will be described in detail with reference to the drawings. Note that the present disclosure is not limited to these embodiments. It goes without saying that each embodiment is an example, and partial replacement or combination of the configurations shown in different embodiments is possible.

[0011] Fig. 1 is a plan view of a secondary battery 1 according to an embodiment of the present disclosure. Fig. 2 is an exploded perspective view of the secondary battery 1 shown in Fig. 1.

[0012] The secondary battery 1 is, for example, a lithium battery. The secondary battery 1 includes an electrode body 10, an exterior body 20, a first tab 30, and a second tab 40.

[0013] The exterior body 20 integrally has a housing portion 21 and a flange portion 22. The housing portion 21 houses the electrode body 10. The housing portion 21 also houses an electrolyte (e.g., a non-aqueous electrolyte). The flange portion 22 extends around the entire periphery of the housing portion 21. In the plan view shown in Fig. 1, the periphery of the flange portion 22 is rectangular.

[0014] As shown in Fig. 2, the exterior body 20 is formed by folding back a single film F at a folding back portion. A protrusion Fa is formed on the film F before folding back, for example, by press working. The protrusion Fa constitutes the housing portion 21. The film F is folded back with the electrode body 10 and the electrolyte housed inside the protrusion Fa. The overlapping portions of the film F around the protrusion Fa are joined to form a flange portion 22.

[0015] Fig. 3 is a plan view of the electrode body 10 shown in Fig. 2. Fig. 4 is a cross-sectional view of the electrode body 10 taken along line IX-IX shown in Fig. 3. Fig. 3 shows a predetermined direction D1, which will be described later, and an orthogonal direction D2 that is orthogonal to the predetermined direction D1.

[0016] The electrode body 10 is a wound type electrode body. As shown in Fig. 4, the electrode body 10 includes a first electrode 50, a second electrode 60, and a separator 70. The first electrode 50 is a positive electrode. The second electrode 60 is a negative electrode. The first electrode 50 and the second electrode 60 have different electric potentials.

[0017] The first pole 50, the second pole 60, and the separator 70 are each in a sheet shape. The first pole 50, the separator 70, and the second pole 60 are laminated in this order. That is, the separator 70 is between the first pole 50 and the second pole 60. The separator 70 electrically insulates the first pole 50 and the second pole 60.

[0018] The first pole 50, the second pole 60 and the separator 70 are wound along a predetermined direction D1, which is the counterclockwise direction in FIG.

[0019] 5 is a partial cross-sectional view of the first electrode 50. The first electrode 50 includes a first current collector 51 and a first active material layer 52.

[0020] The first current collector 51 is in the form of a foil and is made of a material such as aluminum.

[0021] Fig. 6 is a plan view showing the first current collector 51 in a flat, unfolded state. In other words, the first current collector 51 shown in Fig. 6 is not wound along the predetermined direction D1 and is in a flat state. The predetermined direction D1 is the direction in which the arrow shown in Fig. 6 extends. The side indicated by the arrow in Fig. 6 corresponds to the outside of the electrode body 10 when the first pole 50 is wound. The first current collector 51 integrally has a first main body portion 51a and a first protruding portion 51b.

[0022] The first body portion 51a has a rectangular shape with the predetermined direction D1 as the longitudinal direction. In the plan view of the first body portion 51a shown in FIG. 6, the first body portion 51a has a first first side S11 (corresponding to the "first side") and a first second side S12. The first first side S11 extends along the perpendicular direction D2 and is located outside the electrode body 10 when the first pole 50 is wound. The first second side S12 extends along the predetermined direction D1. That is, the first first side S11 and the first second side S12 are perpendicular to each other. The first second side S12 overlaps with the side Sa of the electrode body 10 in the plan view shown in FIG. 3.

[0023] In the plan view shown in Fig. 6, the first protrusion 51b has a rectangular shape protruding from the first side S11 along a predetermined direction D1. In the perpendicular direction D2, the length of the first protrusion 51b is equal to the length of the first main body 51a. The first protrusion 51b is located outside the electrode body 10 as shown in Figs. 3 and 4.

[0024] 5 is disposed on both sides of the first main body portion 51a. In a plan view of the first pole 50 in a state in which the first pole 50 is spread out flat, the periphery of the first main body portion 51a and the periphery of the first active material layer 52 overlap. In other words, in a state in which the first pole 50 is spread out flat, the first active material layer 52 has a rectangular shape with the longitudinal direction being the predetermined direction D1. The first active material layer 52 is not disposed on the first protruding portion 51b.

[0025] The first active material layer 52 contains the active material of the first electrode 50. The active material of the first electrode 50 is preferably, for example, a lithium transition metal composite oxide. Examples of the lithium transition metal composite oxide include LiCoO2, LiNiO2, LiMn2O4, LiMnO2, LiCo 0.5 Ni 0.5 O2, LiNi 0.33 Co 0.33 Mn 0.34 O2, etc., but in particular, LiCoO2 and a lithium transition metal composite oxide having a layered structure containing Li, Ni, Mn, and Co can be preferably used.

[0026] 7 is a partial cross-sectional view of the second electrode 60. The second electrode 60 includes a second current collector 61 and a second active material layer 62.

[0027] The second current collector 61 is in the form of a foil. The material of the second current collector 61 is, for example, a metal such as copper, nickel, iron, titanium, or cobalt, or an alloy or mixture of a combination of these metals.

[0028] Fig. 8 is a plan view showing the second current collector 61 in a flat, unfolded state. In other words, the second current collector 61 shown in Fig. 8 is not wound along the specific direction D1 and is in a flat state. The side indicated by the arrow representing the specific direction D1 in Fig. 8 corresponds to the outside of the electrode assembly 10 when the second pole 60 is wound. The second current collector 61 integrally has a second main body portion 61a and a second protrusion portion 61b.

[0029] The second body portion 61a has a rectangular shape with the predetermined direction D1 as the longitudinal direction. In the plan view of the second body portion 61a shown in FIG. 8, the second body portion 61a has a second first side S21 and a second second side S22 (corresponding to the "second side"). The second first side S21 extends along the perpendicular direction D2 and is located outside the electrode body 10 when the second pole 60 is wound. The second second side S22 extends along the predetermined direction D1. That is, the second first side S21 and the second second side S22 are perpendicular to each other. The second second side S22 overlaps with the side Sa of the electrode body 10 in the plan view shown in FIG. 3.

[0030] In the plan view shown in Fig. 8, the second protrusion 61b has a rectangular shape protruding from the second side S22 along the orthogonal direction D2. There are multiple second protrusions 61b. The multiple second protrusions 61b overlap each other in the plan view of the electrode body 10 shown in Fig. 3.

[0031] The second active material layer 62 shown in Fig. 7 is disposed on both sides of the second main body portion 61a. In a plan view of the second pole 60 in a state in which the second pole 60 is spread out flat, the periphery of the second main body portion 61a and the periphery of the second active material layer 62 overlap. In other words, in a state in which the second pole 60 is spread out flat, the second active material layer 62 has a rectangular shape with the longitudinal direction being the predetermined direction D1. The second active material layer 62 is not disposed on the second protruding portion 61b.

[0032] The second active material layer 62 contains the active material of the second electrode 60. The active material of the second electrode 60 is, for example, silicon.

[0033] In the plan views shown in Fig. 1 and Fig. 3, the first tab 30 has a rectangular flat plate shape. The material of the first tab 30 is, for example, aluminum. The first tab 30 is electrically connected to the first pole 50. Specifically, the first tab 30 is electrically connected to the first protrusion 51b by, for example, laser welding, resistance welding, vibration welding, or the like. In the plan view shown in Fig. 3, the range where the first tab 30 and the first protrusion 51b are electrically connected (hereinafter, referred to as the first range H1) is indicated by hatching.

[0034] The first tab 30 is disposed so as to extend along the predetermined direction D1. In the plan views shown in Figs. 1 and 3, the short side direction of the first tab 30 is along the predetermined direction D1. As shown in Fig. 1, a part of the first tab 30 is exposed to the outside. The first tab 30 is sandwiched between the exterior body 20.

[0035] The second tab 40 has a rectangular flat plate shape in the plan views shown in Figs. 1 and 3. The material of the second tab 40 is, for example, nickel. The second tab 40 is electrically connected to the second pole 60. Specifically, the second protrusions 61b are electrically connected to each other by, for example, laser welding, resistance welding, vibration welding, etc., and the second tab 40 is electrically connected to at least one of the second protrusions 61b by, for example, laser welding, resistance welding, vibration welding, etc. In the plan view shown in Fig. 3, the range in which the second tab 40 and the second protrusion 61b are electrically connected (hereinafter, referred to as the second range H2) is indicated by hatching.

[0036] The second tab 40 is disposed so as to extend along the orthogonal direction D2. In the plan views of Figs. 1 and 3, the longitudinal direction of the second tab 40 is along the orthogonal direction D2. As shown in Fig. 1, a part of the second tab 40 is exposed to the outside. The second tab 40 is sandwiched between the exterior body 20.

[0037] In the plan view shown in Fig. 1, the side overlapping with the first tab 30 and the side overlapping with the second tab 40 are adjacent to each other on the periphery of the flange portion 22. Also, in the plan view of the electrode body 10 shown in Fig. 3, the side Sa of the electrode body 10 faces the second tab 40, and the side Sb of the electrode body 10 overlaps with the first tab 30. In the plan view shown in Fig. 3, the sides Sa and Sb are adjacent to each other.

[0038] Fig. 9 is a plan view of an electrode body 10z according to a comparative example of the embodiment of the present disclosure. Fig. 10 is a cross-sectional view of the electrode body 10z of the comparative example taken along line XX shown in Fig. 9. Fig. 11 is a plan view showing a state in which the second current collector 61z of the second pole 60z of the electrode body 10z of the comparative example shown in Fig. 9 is spread out flat.

[0039] The electrode body 10z of the comparative example differs from the electrode body 10 of the present embodiment in the following two points, and is otherwise configured in the same manner. Note that the reference numerals of the components of the electrode body 10z of the comparative example are those of the components of the electrode body 10 of the present embodiment that correspond to the components of the electrode body 10z of the comparative example, with "z" added to the end. For example, the electrode body 10z includes a first pole 50z and a second pole 60z, the first pole 50z includes a first protrusion 51bz, and the second pole 60z includes a second protrusion 61bz.

[0040] The electrode body 10z of the comparative example differs from the electrode body 10 of the present embodiment in the following two points: In the electrode body 10z of the comparative example, compared to the electrode body 10 of the present embodiment, the second protruding portion 61bz of the second current collector 61z shown in Fig. 11 has a rectangular shape that protrudes from the second first side S21z along a predetermined direction D1 and is located outside the electrode body 10 as shown in Figs. 9 and 10, and the longitudinal direction of the first tab 30z and the longitudinal direction of the second tab 40 are both aligned along the orthogonal direction D2 as shown in Fig. 9, and the first tab 30z and the second tab 40z both overlap with the side Saz.

[0041] Naturally, the first tabs 30, 30z and the second tabs 40, 40z must be electrically insulated and cannot overlap each other in the plan views shown in Figures 3 and 9. Thus, in the plan view of the electrode body 10z of the comparative example shown in Figure 9, the first tab 30z and the second tab 40z overlap the same side Saz in the electrode body 10z and are adjacent to each other while being spaced apart from each other.

[0042] On the other hand, in the plan view of the electrode body 10 of this embodiment shown in Fig. 3, the second tab 40 faces the side Sa of the electrode body 10, and the first tab 30 overlaps with the side Sb of the electrode body 10. Therefore, in the plan views shown in Figs. 3 and 9, with regard to the lengths W2, W2z in the width direction perpendicular to the direction in which the second tabs 40, 40z extend, the length W2 of the second tab 40 of this embodiment can be made greater than the length W2z of the second tab 40z of the comparative example.

[0043] As described above, in the plan view of the electrode body 10z of the comparative example shown in FIG. 9, the first tab 30z and the second tab 40z overlap the same side Saz of the electrode body 10z and are adjacent to each other while being spaced apart from each other. On the other hand, in the plan view of the electrode body 10 of the present embodiment shown in FIG. 3, the second tab 40 faces the side Sa of the electrode body 10, and the first tab 30 overlaps the side Sb of the electrode body 10. Furthermore, in the plan views shown in FIGS. 3 and 9, the sides Sb and Sbz are longer than the sides Sa and Saz. Therefore, in the plan views shown in FIGS. 3 and 9, with respect to the lengths W1 and W1z in the width direction perpendicular to the direction in which the first tabs 30 and 30z extend, the length W1 of the first tab 30 of the present embodiment can be made larger than the length W1z of the first tab 30z of the comparative example.

[0044] Therefore, the cross-sectional area of ​​the second tabs 40, 40z in a plane perpendicular to the direction in which the second tabs 40, 40z extend, and the cross-sectional area of ​​the first tabs 30, 30z in a plane perpendicular to the direction in which the first tabs 30, 30z extend, can be made larger for the first tab 30 and the second tab 40 of the electrode body 10 of this embodiment than for the first tab 30z and the second tab 40z of the electrode body 10z of the comparative example.

[0045] The direction in which the first tab 30 extends (i.e., the predetermined direction D1) is the same as the direction in which the current flows in the first tab 30. The direction in which the second tab 40 extends (i.e., the perpendicular direction D2) is the same as the direction in which the current flows in the second tab 40. Therefore, during charging and discharging of the secondary battery 1, the first tab 30 and the second tab 40 of the electrode body 10 of this embodiment can suppress the amount of heat generated by the second tab 40 and the amount of heat generated by the first tab 30 more than the first tab 30z and the second tab 40z of the electrode body 10z of the comparative example. Therefore, the secondary battery 1 of this embodiment can handle a large current compared to the secondary battery 1 including the electrode body 10z of the comparative example.

[0046] In addition, in the plan view shown in Figure 3, the ratio of the widthwise length L1 (hereinafter sometimes referred to as the first length L1) of the first protrusion 51b along the orthogonal direction D2 perpendicular to the specified direction D1 to the length L2 (same as the length W1: hereinafter sometimes referred to as the second length L2) of the first tab 30 along the orthogonal direction D2 is 0.3 or more.

[0047] As described above, in the plan view of the electrode assembly 10z of the comparative example shown in FIG. 9, the first tab 30z and the second tab 40z are adjacent to each other while being spaced apart from each other on the same side Saz of the electrode assembly 10. In the plan view shown in FIG. 9, when the widthwise length W1z of the first tab 30z and the widthwise length W2z of the second tab 40z are equal to each other, the ratio of the widthwise length W1z of the first tab 30z to the length L3z of the side Saz of the electrode assembly 10z where the first tab 30z and the second tab 40z overlap is smaller than 0.3. In addition, the length L3z of the side Saz of the electrode assembly 10z shown in FIG. 9 is equal to the length of the side Sa of the electrode assembly 10 shown in FIG. 3. Furthermore, the side Sb is longer than the side Sa in the plan view of the electrode assembly 10 shown in FIG. 3.

[0048] Therefore, in the electrode body 10 of this embodiment, when the ratio of the second length L2 of the first tab 30 to the first length L1 of the first protrusion 51b is 0.3 or more, the length W1 of the first tab 30 of this embodiment can be reliably made greater than the length W1z of the first tab 30z of the comparative example in the plan views shown in Figures 3 and 9. Therefore, the secondary battery 1 of this embodiment can reliably handle larger currents than the secondary battery 1 including the electrode body 10z of the comparative example.

[0049] The ratio of the second length L2 of the first tab 30 along the orthogonal direction D2 to the first length L1 of the first protrusion 51b along the orthogonal direction D2 perpendicular to the predetermined direction D1 is 0.9 or less.

[0050] If the ratio of the second length L2 to the first length L1 is greater than 0.9, when an external force such as an impact acts on the secondary battery 1, the first tab 30 presses the electrode body 10, causing the periphery of the electrode body 10 to deform, which may cause a short circuit between the first pole 50 and the second pole 60. Therefore, in the secondary battery 1 of this embodiment, by setting the ratio of the second length L2 to the first length L1 to 0.9 or less, deformation of the periphery of the electrode body 10 is suppressed even when the first tab 30 presses the electrode body 10 when an external force acts on the secondary battery 1. Therefore, it is possible to suppress a short circuit between the first pole 50 and the second pole 60.

[0051] Also, as described above, the length W1 of the first tab 30 of the electrode body 10 of this embodiment can be made larger than the length W1z of the first tab 30z of the electrode body 10z of the comparative example. Furthermore, the length of the side Sb overlapping with the first tab 30 in the plan view of the electrode body 10 of this embodiment shown in Fig. 3 is longer than the length of the side Saz overlapping with the first tab 30z in the plan view of the electrode body 10z of the comparative example shown in Fig. 9. Therefore, the first area H1 of the electrode body 10 of this embodiment can be made larger than the first area H1z of the electrode body 10z of the comparative example.

[0052] Also, as described above, the length W2 of the second tab 40 of the electrode body 10 of this embodiment can be made larger than the length W2z of the second tab 40z of the electrode body 10z of the comparative example. Furthermore, the length of the side Sa facing the second tab 40 in the plan view of the electrode body 10 of this embodiment shown in Fig. 3 is equal to the length of the side Saz overlapping with the second tab 40z in the plan view of the electrode body 10z of the comparative example shown in Fig. 9. Therefore, the second area H2 of the electrode body 10 of this embodiment can be made larger than the second area H2z of the electrode body 10z of the comparative example.

[0053] Therefore, the amount of heat generated in the first area H1 and the second area H2 of the electrode body 10 of this embodiment during charging and discharging of the secondary battery 1 can be suppressed more than the amount of heat generated in the first area H1z and the second area H2z of the electrode body 10z of the comparative example. Therefore, the secondary battery 1 of this embodiment can handle a large current compared to a secondary battery including the electrode body 10z of the comparative example.

[0054] The above-described embodiment is for facilitating understanding of the present disclosure, and is not intended to limit the present disclosure. The present disclosure may be modified or improved without departing from the spirit of the present disclosure, and equivalents thereof are also included in the present disclosure.

[0055] For example, the first pole 50 may be a negative pole and the second pole 60 may be a positive pole.

[0056] 3, the length of side Sb may be shorter than the length of side Sa. In this case, in the plan view of electrode body 10z shown in FIG 9, the length of side Sbz is shorter than the length of side Saz.

[0057] 3, the first tab 30 may be arranged such that the longitudinal direction of the first tab 30 is aligned with the predetermined direction D1. Furthermore, the second tab 40 may be arranged such that the lateral direction of the second tab 40 is aligned with the orthogonal direction D2.

[0058] 12 is a plan view of the electrode assembly 10 of the secondary battery 1 according to a first modified example of the embodiment of the present disclosure. The electrode assembly 10 of this first modified example is different from the electrode assembly 10 of the above embodiment in that the first tab 130 overlaps with the side Sa of the electrode assembly 10. In addition, in this first modified example, the first tab 130 is formed so that the length L14 of the first area H1 along the predetermined direction D1 is longer than the length L15 of the portion of the first tab 130 that does not overlap with the first pole 50 along the predetermined direction D1. As a result, even when the first tab 130 overlaps with the side Sa of the electrode assembly 10 in the plan view of FIG. 12, the amount of heat generated in the first area H1 can be suppressed.

[0059] 13 is a plan view showing the second current collector 261 in a state where the secondary battery 1 according to the second modification of the embodiment of the present disclosure is laid out flat. The second current collector 261 has one second protrusion 261b. The second protrusion 261b is a rectangular shape that protrudes from the entire second side S22 along the orthogonal direction D2. In this second modification, the second tab 40 is electrically connected to the second protrusion 61b in a state where the second protrusion 61b is wound along the predetermined direction D1.

[0060] The present disclosure may also be implemented in the following combinations:

[0061] (1) an electrode assembly including a first electrode, a second electrode having a different potential from the first electrode, and a separator between the first electrode and the second electrode, the first electrode, the second electrode, and the separator being wound in a predetermined direction; a first tab electrically connected to the first pole; a second tab electrically connected to the second pole; the first electrode comprises a foil-shaped first current collector and a first active material layer overlapping the first current collector and containing an active material of the first electrode; the second electrode comprises a foil-like second current collector and a second active material layer overlapping the second current collector and containing an active material of the second electrode; The first current collector is a first main body portion that has a first side extending along a direction perpendicular to the predetermined direction in a plan view in a state where the first main body portion is spread out flat and overlaps with the first active material layer; a first protruding portion that protrudes from the first side along the predetermined direction in a plan view in a state where the electrode is spread out flat and does not overlap with the first active material layer, The second current collector is a second main body portion having a second side extending along the predetermined direction in a plan view in a state where the substrate is spread out flat and overlapping the second active material layer; a second protruding portion that protrudes from the second side along a direction perpendicular to the predetermined direction in a plan view in a state where the electrode is spread out flat and does not overlap with the second active material layer, the first tab is electrically connected to the first protrusion; The second tab is electrically connected to the second protrusion. Secondary battery.

[0062] (2) The first tab is disposed in a state of extending along the predetermined direction, The second tab is disposed so as to extend along a direction perpendicular to the predetermined direction. The secondary battery according to (1).

[0063] (3) a ratio of a second length of the first tab along a direction perpendicular to the predetermined direction to a first length of the first protrusion along the direction perpendicular to the predetermined direction is 0.3 or more; A secondary battery according to (1) or (2).

[0064] (4) a ratio of a second length of the first tab along a direction perpendicular to the predetermined direction to a first length of the first protrusion along the direction perpendicular to the predetermined direction is 0.9 or less; A secondary battery according to any one of (1) to (3).

[0065] (5) The second current collector has a plurality of the second protrusions. A secondary battery according to any one of (1) to (4). [Explanation of symbols]

[0066] 1 Secondary battery 10 Electrode body 30 First Tab 40 Second Tab 50 1st pole 51 First current collector 51a 1st body part 51b 1st protrusion 52 1st active material layer 60 2nd pole 61 Second current collector 61a Second main body part 61b Second protrusion 62 Second active material layer 70 Separator D1 Specified direction S11 1st side (1st side) S22 2nd side (2nd side)

Claims

1. an electrode assembly including a first electrode, a second electrode having a potential different from that of the first electrode, and a separator between the first electrode and the second electrode, the first electrode, the second electrode, and the separator being wound in a predetermined direction; a first tab electrically connected to the first pole; a second tab electrically connected to the second pole; the first electrode comprises a foil-shaped first current collector and a first active material layer overlapping the first current collector and containing an active material of the first electrode; the second electrode comprises a foil-shaped second current collector and a second active material layer overlapping the second current collector and containing an active material of the second electrode; The first current collector is a first main body portion having a first side extending along a direction perpendicular to the predetermined direction in a plan view in a flat spread state and overlapping with the first active material layer; a first protruding portion that protrudes from the first side along the predetermined direction in a plan view in a state where the electrode is spread out flat and does not overlap with the first active material layer, The second current collector is a second main body portion having a second side extending along the predetermined direction in a plan view in a state where the substrate is spread out flat and overlapping the second active material layer; a second protruding portion that protrudes from the second side along a direction perpendicular to the predetermined direction in a plan view in a state where the electrode is spread out flat and does not overlap with the second active material layer, the first tab is electrically connected to the first protrusion; The second tab is electrically connected to the second protrusion. Secondary battery.

2. The first tab is disposed in a state of extending along the predetermined direction, The second tab is disposed so as to extend along a direction perpendicular to the predetermined direction. The secondary battery according to claim 1 .

3. a ratio of a second length of the first tab along a direction perpendicular to the predetermined direction to a first length of the first protrusion along the direction perpendicular to the predetermined direction is 0.3 or more; The secondary battery according to claim 1 .

4. a ratio of a second length of the first tab along a direction perpendicular to the predetermined direction to a first length of the first protrusion along the direction perpendicular to the predetermined direction is 0.9 or less; The secondary battery according to claim 1 .

5. The second current collector has a plurality of the second protrusions. The secondary battery according to claim 1 .

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