JP2020057587A - Electrode body, secondary battery and secondary battery manufacturing method - Google Patents

Abstract

To provide an electrode body, a secondary battery and a secondary battery manufacturing method, with which it is possible to increase a power storage capacity of the electrode body without causing short circuit due to breakage of a separator in the electrode body, in which a positive electrode sheet, a negative electrode sheet and the separator are laminated, and without causing lowering of battery performance.SOLUTION: In an electrode body 30 according to the present invention, positive electrode sheets 200 to 202, negative electrode sheets 210 to 212, and separators 220 to 226 are laminated. In a positive electrode current collecting end part of the electrode body 30, the positive electrode sheets, the negative electrode sheets, and the separators are buckled at least in part inwardly in a lamination direction at a first buckling position positioned inside with respect to end parts of the negative electrode sheets in a width direction. In a negative electrode current collecting end part of the electrode body 30, the negative electrode sheets, the positive electrode sheets, and the separators are buckled at least in part inwardly in the lamination direction at a second buckling position positioned inside with respect to end parts of the positive electrode sheets in the width direction.SELECTED DRAWING: Figure 2

Description

  The present invention relates to an electrode assembly, a secondary battery, and a method for manufacturing a secondary battery, and in particular, an electrode assembly in which a positive electrode sheet, a negative electrode sheet, and a separator are stacked, a secondary battery including the electrode assembly, and a method for manufacturing the secondary battery. About the method.

  At present, rectangular secondary batteries such as lithium-ion batteries and nickel-metal hydride batteries are used in electric vehicles, hybrid vehicles, plug-in hybrid vehicles, and the like. Such a prismatic secondary battery includes an electrode body such as a wound electrode body or a stacked electrode body. At the end in the width direction of the electrode body, the active material uncoated portion of the current collector extends in the width direction and is joined to the current collector plate. At this time, since the ends of the electrode body are bonded to the current collector plate in a bundled state, as shown in FIG. 3, the active material uncoated portion of the extended current collector extends outside the lamination direction of the electrode body. However, the separator buckles inward in the stacking direction at the end of the adjacent electrode sheet, and the separator comes into contact with the end of the electrode sheet to apply pressure to the separator. As a result, there is a problem that the separator is damaged and a short circuit occurs.

  In this regard, in the electrode assembly disclosed in Patent Document 1, by buckling the current collector near the current collector, the current collector is prevented from contacting the adjacent counter electrode plate, Prevent short circuit from occurring.

JP-A-2015-82499

  However, the electrode assembly disclosed in Patent Literature 1 employs a configuration in which the current collector buckles in the vicinity of the current collector in order to prevent the current collector from contacting the adjacent counter electrode plate. (FIG. 3 of Patent Document 1), it is necessary to secure a bent area of a certain size at the current collecting end of the electrode body. For this reason, the region of the positive electrode mixture layer and the region of the negative electrode mixture layer cannot be expanded outward in the width direction, and there is a problem that the storage capacity of the electrode body cannot be increased.

  The present invention has been made in order to solve such a problem, and does not cause a short circuit due to breakage of a separator in an electrode body in which a positive electrode sheet, a negative electrode sheet and a separator are laminated, and improve battery performance. It is an object of the present invention to provide an electrode body, a secondary battery, and a method for manufacturing a secondary battery, which can increase the storage capacity of the electrode body without lowering the battery capacity.

  The electrode body according to one embodiment of the present invention is an electrode body in which a positive electrode sheet, a negative electrode sheet, and a separator that insulates the positive electrode sheet and the negative electrode sheet are stacked, and a positive electrode current collecting end of the electrode body has At least a part of the positive electrode sheet, the negative electrode sheet, and the separator is seated inward in the stacking direction at a first buckling position located inside an end of the negative electrode sheet in a width direction substantially perpendicular to the stacking direction. At the negative electrode current collecting end of the electrode body, at least a part of the negative electrode sheet, the positive electrode sheet, and the separator is located in a second seat located inside the end of the positive electrode sheet in the width direction. Buckled in the stacking direction at the bending position.

  Further, the positive electrode sheet includes a positive electrode current collector, and a positive electrode mixture layer formed on both surfaces of the positive electrode current collector, and at a positive electrode current collecting end of the electrode body, an end of the positive electrode mixture layer The portion is disposed inside the end of the negative electrode sheet in the width direction, and the first buckling position is between the end of the positive electrode mixture layer and the end of the negative electrode sheet. Is preferred. Further, the negative electrode sheet includes a negative electrode current collector, and a negative electrode mixture layer formed on both surfaces of the negative electrode current collector, and at a negative electrode current collecting end of the electrode body, an end of the negative electrode mixture layer The portion is disposed inside the end of the positive electrode sheet in the width direction, and the second buckling position is between the end of the negative electrode mixture layer and the end of the positive electrode sheet. Is preferred.

  Further, when the end of the positive electrode mixture layer and the end of the negative electrode mixture layer have a tapered shape, the first buckling position is a taper start position of the positive electrode mixture layer, It is preferable that the second buckling position is between an end of the positive electrode sheet and the end of the positive electrode sheet. In this case, the buckling angle of the positive electrode sheet, the negative electrode sheet, and the separator at the positive electrode current collecting end is substantially the same as the angle formed by the tapered shape of the positive electrode mixture layer, and at the negative electrode current collecting end. The buckling angles of the positive electrode sheet, the negative electrode sheet, and the separator are preferably substantially the same as the angle formed by the tapered shape of the negative electrode mixture layer.

  Furthermore, when the end of the positive electrode mixture layer and the end of the negative electrode mixture layer have a substantially vertical surface, the first buckling position is substantially perpendicular to the positive electrode mixture layer and the negative electrode sheet. It is preferable that the second buckling position is between a substantially vertical surface of the negative electrode mixture layer and an end of the positive electrode sheet.

  Further, the electrode body may be a wound electrode body or a laminated electrode body.

  Further, the electrode body according to one embodiment of the present invention has a contact surface that is in contact with the positive electrode current collecting end portion, and applies stress to the positive electrode current collecting end portion through the contact surface, thereby forming the positive electrode A sheet, a positive electrode terminal that buckles at least a part of the negative electrode sheet and the separator, and a contact surface that is in contact with the negative electrode current collecting end portion. Stress is applied to the negative electrode current collecting end portion through the contact surface. In addition, a negative electrode terminal that buckles at least a part of the negative electrode sheet, the positive electrode sheet, and the separator can be provided. It is preferable that the widthwise inner end of the contact surface of the positive electrode terminal and the widthwise inner end of the contact surface of the negative electrode terminal are curved.

  Further, a secondary battery according to an embodiment of the present invention includes the electrode body.

  Furthermore, the method for manufacturing a secondary battery according to one embodiment of the present invention includes manufacturing a secondary battery including an electrode body in which a positive electrode sheet, a negative electrode sheet, and a separator that insulates the positive electrode sheet and the negative electrode sheet are stacked. A method, wherein at least a part of the positive electrode sheet, the negative electrode sheet and the separator at a positive electrode current collecting end of the electrode body are located inside an end of the negative electrode sheet in a width direction substantially perpendicular to a laminating direction. A first buckling step of buckling inward in the stacking direction at a first buckling position, and at least a part of the negative electrode sheet, the positive electrode sheet, and the separator at a negative electrode current collecting end of the electrode body, A second buckling step of buckling inward in the stacking direction at a second buckling position located inside the end of the positive electrode sheet in the width direction.

  Furthermore, in the method for manufacturing a secondary battery according to one embodiment of the present invention, in the first buckling step, a stress is applied to the positive electrode current collecting end portion via the pressing surfaces of the upper pressing member and the lower pressing member. In addition, at least a part of the positive electrode sheet, the negative electrode sheet, and the separator are buckled, and in the second buckling step, the negative electrode current is collected via pressing surfaces of an upper pressing member and a lower pressing member. By applying a stress to the end, at least a part of the negative electrode sheet, the positive electrode sheet, and the separator can be buckled. It is preferable that an end of the pressing surface of the upper pressing member on the electrode body side and an end of the pressing surface of the lower pressing member on the electrode body side are curved.

  According to the present invention, it is possible to increase the storage capacity of an electrode body without causing a short circuit due to breakage of the separator in an electrode body in which a positive electrode sheet, a negative electrode sheet and a separator are laminated, and without lowering battery performance. The present invention can provide an electrode body, a secondary battery, and a method for manufacturing a secondary battery, which can perform the following.

1 is a schematic diagram illustrating a battery module that is a secondary battery according to an embodiment of the present invention. FIG. 3 is a horizontal cross-sectional view showing a positive electrode current collecting end on the outer side in the stacking direction of the electrode body according to one embodiment of the present invention. It is a figure which shows the mode of buckling in the current collection end part of the conventional electrode body. It is a figure which shows the mode of buckling in the current collection end part of the conventional electrode body. It is a figure which shows an example of the upper side pressing member and the lower side pressing member for buckling the collector end of the electrode body which concerns on one Embodiment of this invention. FIG. 6 is a diagram illustrating a state where a current collecting end of an electrode body is buckled using the upper pressing member and the lower pressing member illustrated in FIG. 5.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. 1 is a schematic diagram illustrating a battery module 10 that is a rectangular secondary battery according to an embodiment of the present invention. The battery module 10 houses an electrode body such as a wound electrode body or a laminated electrode body which is a battery cell. These electrode bodies include an electrode sheet constituting a positive electrode (hereinafter, referred to as “positive sheet”) and an electrode sheet constituting a negative electrode (hereinafter, referred to as “negative electrode sheet”). The electricity stored in the positive electrode sheet and the negative electrode sheet is collected at the positive current collecting end and the negative current collecting end, respectively, and output from the positive terminal 11 and the negative terminal 12.

  In the following description, a direction in which the positive electrode sheet and the negative electrode sheet in the battery module 10 are stacked is referred to as a stacking direction, and a direction substantially perpendicular to the stacking direction is referred to as a width direction. In the present embodiment, the positive electrode terminal 11 and the negative electrode terminal 12 are arranged on the upper surface of the battery module 10, but the positive electrode terminal 11 and the negative electrode terminal 12 may be arranged on the side surface in the width direction of the battery module 10.

  FIG. 2 is a horizontal cross-sectional view showing the positive electrode collecting end on the outer side in the stacking direction of the electrode body according to one embodiment of the present invention, and the electrode body 20 before being pressed and pressed from both sides in the stacking direction. The rear electrode body 30 is shown. FIG. 2 shows only one outside of the positive electrode current collecting ends of the electrode bodies 20 and 30 in the stacking direction, but the other outside of the positive electrode current collecting ends of the electrode bodies 20 and 30 is similarly seated. Succumbed.

  The electrode body 20 includes positive electrode sheets 200, 201, 202, negative electrode sheets 210, 211, 212, and separators 220 to 226, and the positive electrode sheet, the negative electrode sheet, and the separator are stacked. The separators 221 to 226 that are not the outermost in the laminating direction are arranged between the positive electrode sheets 200, 201, 202 and the negative electrode sheets 210, 211, 212, and insulate these positive electrode sheets and negative electrode sheets. Here, the wound electrode body is formed, for example, by laminating and winding one positive electrode sheet, one negative electrode sheet, and two separators. On the other hand, a laminated electrode body is formed by laminating a plurality of positive electrode sheets, a plurality of negative electrode sheets, and a plurality of separators.

  The positive electrode sheets 200, 201, and 202 include positive electrode current collectors 200a, 201a, and 202a, respectively, and positive electrode mixture layers 200b, 201b, and 202b formed on both surfaces of these positive electrode current collectors. The positive electrode current collectors 200a, 201a, and 202a extend outward in the width direction and are joined to a positive electrode current collector plate (not shown). The positive electrode mixture layers 200b, 201b, and 202b are composed of a positive electrode mixture slurry containing a positive electrode active material (such as lithium cobalt oxide), a conductive agent, and a binder, and the positive electrode mixture slurry is applied to a positive electrode current collector (such as aluminum). Formed by dry quenching. As shown in the drawing, at the positive electrode current collecting end, the ends of the tapered positive electrode mixture layers 200b, 201b, and 202b are arranged inside the ends of the negative electrode sheets 210, 211, and 212 in the width direction. You.

  Negative electrode sheets 210, 211, 212 include negative electrode current collectors 210a, 211a, 212a, respectively, and negative electrode mixture layers 210b, 211b, 212b formed on both surfaces of these negative electrode current collectors. The negative electrode current collectors 210a, 211a, and 212a extend outward in the width direction and are joined to the negative electrode current collector plate (not shown). The negative electrode mixture layers 210b, 211b, and 212b are formed of a negative electrode mixture slurry containing a negative electrode active material (eg, graphite), a conductive agent, and a binder, and the negative electrode mixture slurry is applied to a negative electrode current collector (eg, copper). It is formed by dry quenching. Similarly to the positive electrode current collecting end, at the negative electrode current collecting end, the ends of the tapered negative electrode mixture layers 210b, 211b, and 212b are located inside the ends of the positive electrode sheets 200, 201, and 202 in the width direction. (Not shown).

  In the method of manufacturing a secondary battery of the present invention, pressure is applied to the positive electrode current collecting end and the negative electrode current collecting end of the electrode body 20 from both sides in the stacking direction. More specifically, at the positive electrode current collecting end of the electrode body 20, as shown in the figure, the taper start positions of the positive electrode mixture layers 200b, 201b, and 202b and the end positions of the negative electrode sheets 210, 211, and 212 The electrode body 20 is pressed so that the electrode body 20 is buckled at the first buckling position between the two. Here, the taper start position of the positive electrode mixture layers 200b, 201b, and 202b is the outermost position in the width direction among the positions where the positive electrode mixture layers 200b, 201b, and 202b are in contact with the separators 221 to 226.

  When the electrode body 20 is pressed from the outside in the stacking direction, the positive electrode current collecting end of the electrode body 20 changes into a shape like the electrode body 30. At the positive electrode current collecting end of the electrode body 30, the positive electrode current collectors 200a, 201a, and 202a, the negative electrode sheets 211 and 212, and the separators 222, 223, 224, 225, and 226 are stacked in the first buckling position in the stacking direction. Buckle inward.

  Similarly, at the negative electrode current collecting end of the electrode body 20, the second buckling position between the taper start position of the negative electrode mixture layers 210b, 211b, 212b and the end position of the positive electrode sheets 200, 201, 202 The electrode body 20 is pressed so that the electrode body 20 is buckled. Here, the taper start position of the negative electrode mixture layers 210b, 211b, 212b is the outermost position in the width direction among the positions where the negative electrode mixture layers 210b, 211b, 212b and the separators 221 to 226 are in contact. When the electrode body 20 is pressed from the outside in the stacking direction, the negative electrode current collectors 210a, 211a, 212a, the positive electrode sheets 200, 201, 202, the separators 222, 223, 224, and 225 are formed at the negative electrode current collecting end of the electrode body 20. , 226 buckle in the stacking direction in the second buckling position.

  In this figure, the negative electrode sheet 210 and the separators 220 and 221 do not buckle inward in the stacking direction for convenience of explanation, but the magnitude of the pressing force applied to the electrode body by the method of manufacturing a secondary battery of the present invention. , The negative electrode sheet 210 and the separators 220 and 221 buckle inward in the stacking direction. The degree of buckling of the positive electrode sheet, the negative electrode sheet, and the separator on the outer side in the stacking direction is larger than that of the positive electrode sheet, the negative electrode sheet, and the separator on the inner side in the stacking direction. Further, the positive electrode sheet, the negative electrode sheet and the separator at the center do not buckle. That is, according to the method for manufacturing a secondary battery of the present invention, at least a part of the positive electrode sheet, the negative electrode sheet and the separator buckle in the laminating direction.

  FIG. 5 is a diagram illustrating the upper pressing member 40 and the lower pressing member 50 for buckling the current collecting end of the electrode body 30. FIG. 6 is a diagram illustrating a state where the current collecting end of the electrode body 30 is buckled using the upper pressing member 40 and the lower pressing member 50.

  The upper pressing member 40 is a member that is fixed to the horn and that presses the positive current collecting end and the negative current collecting end of the electrode body 30 from above. The upper pressing member 40 buckles the positive electrode sheet, the negative electrode sheet, and the separator at the current collecting end of the electrode body 30 by applying stress to the current collecting end of the electrode body 30 via the bottom surface that is the pressing surface. The end 41 of the pressing surface of the upper pressing member 40 on the electrode body side is curved as shown in FIG. The upper pressing member 40 can be provided with an opening 42 in order to avoid interference with the current collecting terminal attached to the current collecting end of the electrode body 30.

  The lower pressing member 50 is a member that is fixed to the anvil and presses the positive electrode collecting end and the negative electrode collecting end of the electrode body 30 from below. The lower pressing member 50 buckles the positive electrode sheet, the negative electrode sheet, and the separator at the current collecting end of the electrode body 30 by applying stress to the current collecting end of the electrode body 30 via the upper surface that is the pressing surface. . The end 51 of the pressing surface of the lower pressing member 50 on the electrode body side is curved as shown in FIG.

  As the horn moves downward, the upper pressing member 40 moves toward the lower pressing member 50, and as shown in FIG. 6, the pressing surface of the upper pressing member 40 and the lower pressing member Since stress is applied to the current collecting end of the electrode body 30 via the pressing surface of the member 50, stress can be dispersedly applied to the current collecting end of the electrode body 30. For this reason, since stress is not intensively applied to a part of the separator included in the current collecting end portion, it is possible to prevent the separator from being damaged and to prevent a short circuit caused by this. . In addition, since the end surfaces 41 and 51 of the pressing surfaces of the upper pressing member 40 and the lower pressing member 50 on the electrode body side are curved, the current collecting end of the electrode body 30 in contact with these ends is smoothly seated. And the separator included in the current collecting end can be reliably prevented from being broken.

  In the above-described embodiment, the positive electrode current collector, the negative electrode sheet, and the separator are buckled at the first buckling position on the inner side in the width direction from the end of the negative electrode sheet at the positive electrode current collecting end, and at the negative electrode current collecting end. The negative electrode current collector, the positive electrode sheet, and the separator are buckled at the second buckling position on the inner side in the width direction from the end of the positive electrode sheet. For this reason, the positive electrode current collector is bent at the end position of the negative electrode sheet as shown in FIG. 3 or the positive electrode current collector is bent at the end position of the negative electrode sheet as compared with the positive electrode current collector. The current collector and the negative electrode current collector can reduce stress applied to adjacent separators, respectively, and can prevent short circuit due to breakage of the separator. Further, unlike the configuration in which the current collector is buckled at the current collector end of the electrode body in the width direction outside of the end of the separator as shown in FIG. 4, a buckling region is formed outside the end of the separator in the width direction. There is no need to provide For this reason, the area of the positive electrode mixture layer at the positive electrode current collecting end can be expanded, and the area of the negative electrode mixture layer at the negative electrode current collecting end can be expanded, so that the storage capacity of the electrode body can be increased. .

  Further, in the above-described embodiment, the positive electrode current collector and the negative electrode sheet are buckled at the first buckling position where the positive electrode mixture layer does not exist, and the negative electrode current collector and the positive electrode sheet are Although buckling is performed at the second buckling position that does not exist, in the process of creating the present invention, even if both the positive electrode sheet and the negative electrode sheet buckle at such a buckling position, there is no adverse effect on battery performance. It is newly found. That is, according to the present invention, the battery performance can be prevented from deteriorating by buckling the electrode sheet at the above-described first and second buckling positions.

  The present invention is not limited to the above-described embodiment, and can be appropriately changed without departing from the gist. For example, in the embodiment shown in FIG. 2, the electrode sheet and the separator are buckled at a position outside the taper start position of the positive electrode mixture layer in the width direction and at a position outside the taper start position of the negative electrode mixture layer in the width direction. However, in another embodiment, the electrode sheet and the separator may be buckled at the taper start position of the positive electrode mixture layer and the taper start position of the negative electrode mixture layer. This is because the tapered portion of these mixture layers has a small contribution to battery performance, and therefore, even if the electrode sheet adjacent to the tapered portion is buckled, the battery performance is not adversely affected. In this case, the buckling angle of the electrode sheet and the separator at the positive electrode current collecting end is substantially equal to the angle formed by the tapered shape of the positive electrode mixture layer, and the buckling angle of the electrode sheet and the separator at the negative electrode current collecting end is It is preferable that the angle is approximately the same as the angle formed by the tapered shape of the negative electrode mixture layer. Thereby, the positive electrode mixture layer and the negative electrode mixture layer are not pressed against each other, and the adverse effect on the battery performance can be reliably prevented.

  In the above-described embodiment, the end of the positive electrode mixture layer and the end of the negative electrode mixture layer have a tapered shape. In other embodiments, the end of the positive electrode mixture layer and the negative electrode mixture layer have a tapered shape. May have a substantially vertical surface. In this case, the first buckling position is between the substantially vertical surface of the end of the positive electrode mixture layer and the end of the negative electrode sheet, and the second buckling position is the end of the negative electrode mixture layer. And the edge of the positive electrode sheet.

  Further, in the above-described embodiment, the widthwise inner limit position of the first buckling position at the positive electrode current collecting end is the taper start position of the positive electrode mixture layers 200b, 201b, and 202b. Then, as long as the battery performance is not adversely affected, the position in the width direction from the taper start position of the positive electrode mixture layers 200b, 201b, and 202b may be set as the limit position in the width direction inside of the first buckling position. . Similarly, at the negative electrode current collecting end, a position in the width direction inside of the taper start position of the negative electrode mixture layers 210b, 211b, 212b may be set as a widthwise inner limit position of the second buckling position.

  Further, in another embodiment, a positive electrode terminal and a negative electrode terminal having the same shape as the lower shape of the upper pressing member 40 and the upper shape of the lower pressing member 50 can be attached to the current collecting end of the electrode body 30. The positive electrode terminal has a contact surface that comes into contact with the positive electrode current collecting end of the electrode body 30, and applies stress to the positive electrode current collecting end via the contact surface to form a positive electrode sheet, a negative electrode sheet, and a separator. At least a portion can be buckled. The negative electrode terminal has a contact surface that comes into contact with the negative electrode current collecting end of the electrode body 30, and by applying stress to the negative electrode current collecting end via the contact surface, the negative electrode sheet, the positive electrode sheet, and the separator At least a portion can be buckled. The widthwise inner end of the contact surface of the positive terminal and the widthwise inner end of the contact surface of the negative terminal are similar to the ends 41 and 51 of the pressing surfaces of the upper pressing member 40 and the lower pressing member 50 on the electrode body side. Preferably it is curved.

Reference Signs List 10 battery module 11 positive electrode terminal 12 negative electrode terminal 20 electrode body 30 electrode body 200 to 202 positive electrode sheet 200a to 202a positive electrode current collector 200b to 202b positive electrode mixture layer 210 to 212 negative electrode sheet 210a to 212a negative electrode current collector 210b to 212b negative electrode Mixture layer 220-226 Separator

Claims (12)

A positive electrode sheet, a negative electrode sheet, and an electrode body in which a separator for insulating the positive electrode sheet and the negative electrode sheet is laminated,
At the positive electrode current collecting end of the electrode body, at least a part of the positive electrode sheet, the negative electrode sheet and the separator is located inside the end of the negative electrode sheet in the width direction substantially perpendicular to the laminating direction. Buckled in the stacking direction at the buckling position
At the negative electrode current collecting end of the electrode body, at least a part of the negative electrode sheet, the positive electrode sheet, and the separator are at a second buckling position located inside the end of the positive electrode sheet in the width direction. An electrode body characterized in that it is buckled inward in the stacking direction. The positive electrode sheet includes a positive electrode current collector, and a positive electrode material mixture layer formed on both surfaces of the positive electrode current collector,
At the positive electrode current collecting end, an end of the positive electrode mixture layer is disposed inside an end of the negative electrode sheet in the width direction,
The first buckling position is between an end of the positive electrode mixture layer and an end of the negative electrode sheet,
The negative electrode sheet includes a negative electrode current collector, and a negative electrode mixture layer formed on both surfaces of the negative electrode current collector,
At the negative electrode current collecting end, an end of the negative electrode mixture layer is disposed inside an end of the positive electrode sheet in the width direction,
The electrode body according to claim 1, wherein the second buckling position is between an end of the negative electrode mixture layer and an end of the positive electrode sheet. When the end of the positive electrode mixture layer and the end of the negative electrode mixture layer have a tapered shape,
The first buckling position is between a taper start position of the positive electrode mixture layer and an end of the negative electrode sheet,
The electrode body according to claim 2, wherein the second buckling position is between a taper start position of the negative electrode mixture layer and an end of the positive electrode sheet. The buckling angle of the positive electrode sheet, the negative electrode sheet and the separator at the positive electrode current collecting end is substantially the same as the angle formed by the tapered shape of the positive electrode mixture layer,
4. The electrode body according to claim 3, wherein a buckling angle of the positive electrode sheet, the negative electrode sheet, and the separator at the negative electrode current collecting end is substantially equal to an angle formed by a tapered shape of the negative electrode mixture layer. When the end of the positive electrode mixture layer and the end of the negative electrode mixture layer have a substantially vertical surface,
The first buckling position is between a substantially vertical surface of the positive electrode mixture layer and an end of the negative electrode sheet,
The electrode body according to claim 2, wherein the second buckling position is between a substantially vertical surface of the negative electrode mixture layer and an end of the positive electrode sheet.   The electrode body according to any one of claims 1 to 5, wherein the electrode body is a wound electrode body or a laminated electrode body. A contact surface that contacts the positive electrode current collecting end portion, and stress is applied to the positive electrode current collecting end portion through the contact surface to seat at least a part of the positive electrode sheet, the negative electrode sheet, and the separator. A positive terminal to bend,
A contact surface that contacts the negative electrode current collecting end portion, and stress is applied to the negative electrode current collecting end portion through the contact surface to seat at least a part of the negative electrode sheet, the positive electrode sheet, and the separator. The electrode body according to any one of claims 1 to 6, further comprising: a negative electrode terminal that bends.   The electrode body according to claim 7, wherein a width direction inner end of the contact surface of the positive electrode terminal and a width direction inner end of the contact surface of the negative electrode terminal are curved.   A secondary battery comprising the electrode body according to claim 1. A method for manufacturing a secondary battery including a positive electrode sheet, a negative electrode sheet, and an electrode body in which a separator for insulating the positive electrode sheet and the negative electrode sheet is stacked,
At least a part of the positive electrode sheet, the negative electrode sheet, and the separator at the positive electrode current collecting end of the electrode body is located inside the end of the negative electrode sheet in the width direction substantially perpendicular to the laminating direction. A first buckling step of buckling inward in the stacking direction at the buckling position;
At least a part of the negative electrode sheet, the positive electrode sheet, and the separator at the negative electrode current collecting end of the electrode body are stacked at a second buckling position located inside the end of the positive electrode sheet in the width direction. And a second buckling step of buckling inward in the direction. In the first buckling step, at least a portion of the positive electrode sheet, the negative electrode sheet, and the separator is formed by applying stress to the positive electrode current collecting end via the pressing surfaces of the upper pressing member and the lower pressing member. Buckle,
In the second buckling step, at least a part of the negative electrode sheet, the positive electrode sheet, and the separator is formed by applying stress to the negative electrode current collecting end portion via the pressing surfaces of the upper pressing member and the lower pressing member. The method for manufacturing a secondary battery according to claim 10, wherein the secondary battery is buckled.   The secondary according to claim 11, wherein an end of the pressing surface of the upper pressing member on the electrode body side and an end of the pressing surface of the lower pressing member on the electrode body side are curved. Battery manufacturing method.

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