JP2015090774A - Power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device with improved collapse resistance of an electrode assembly.SOLUTION: A secondary battery 1 comprises an electrode assembly 20, a conductive member 31, and a case 10. The electrode assembly 20 comprises: a main body part 21 composed of a first active material part 26 provided with an active material of a positive electrode 24, a second active material part 28 provided with an active material of a negative electrode 25, and a separator S; a first collector part 22; and a second collector part 23. The conductive member 31 includes a base part 41 bonded to the first collector part 22 and a flange part 42 erected in an end on the main body part 21 side of the base part 41. The shortest distance D1 between a tip 42a of the flange part 42 and a first inner surface 10a facing a principal surface 22a to which the base part 41 of the first collector part 22 or the second collector part 23 is bonded in an inner surface of the case 10 is shorter than the shortest distance D2 between the positive electrode 24 to which the base part 41 is bonded and the first inner surface 10a.

Description

  The present invention relates to a power storage device.

  Conventionally, as a secondary battery which is a kind of power storage device, for example, a lithium ion secondary battery, a nickel metal hydride secondary battery, and the like are well known. Such a secondary battery accommodates an electrode assembly having a separator provided between a portion provided with a positive electrode active material and a portion provided with a negative electrode active material. The electrode assembly has a main body and a current collector, and a rectangular sheet-like conductive member extending to an external terminal is joined to the current collector.

  In such a secondary battery, when the conductive member is pressed toward the main body by the external force from the side surface, the conductive member contacts the electrode assembly other than the current collector, and in some cases, the conductive member may be the electrode assembly. As a result, the secondary battery is crushed (side crushed). This is considered to be due to stress concentration at the contacted portion when the conductive member contacts the electrode assembly other than the current collector. Therefore, by setting up a flange at the end of the main body side of the conductive member, the contact area of the conductive member is increased, the stress concentration during the contact of the conductive member is reduced, and the above-mentioned resistance to collapse (crushing) For example, Patent Literatures 1 to 3 listed below disclose techniques for improving tolerance.

JP 2006-236790 A

  However, even in the secondary battery described above, the tip of the flange portion may break through the electrode assembly, and sufficient crush resistance could not be obtained.

  In view of the above, an object of the present invention is to provide a power storage device with improved crush resistance.

  A power storage device according to one embodiment of the present invention includes a positive electrode and a negative electrode each provided with an active material, a first active material portion provided with a positive electrode active material, and a second active material provided with a negative electrode active material. A power storage device comprising: an electrode assembly having a separator provided between the electrode portion; a conductive member; and a case in which the electrode assembly and the conductive member are accommodated. A main body composed of a portion provided with a material, a portion provided with a negative electrode active material, and a separator, a first current collector composed of a portion where no active material in the positive electrode is provided, and a negative electrode A second current collecting part configured with a portion where no active material is provided, and the positive electrode includes a first active material part on which the separator and the negative electrode are stacked, and a first current constituting the first current collecting part A terminal portion, a first active material portion and a first terminal portion located between the first terminal portion; A negative electrode, a second active material portion on which the separator and the positive electrode are stacked, a second terminal portion constituting the second current collector, and a second active material portion and a second terminal portion. A second connecting portion located between the first current collecting portion and the second current collecting portion; It has a flange portion that is spaced apart from the one connection portion or the second connection portion, and the tip of the flange portion is joined to the base of the first current collector or the second current collector among the inner surfaces of the case. The shortest distance D1 between the first inner surface facing the surface is shorter than the shortest distance D2 between the positive electrode or negative electrode to which the base is bonded and the first inner surface.

  In this power storage device, the shortest distance D1 between the front end of the flange portion and the first inner surface is shorter than the shortest distance D2 between the positive electrode or negative electrode to which the base is joined and the first inner surface, so that the conductive member is the main body portion. Even when the flange is in contact with the electrode assembly, the tip of the flange does not contact the electrode assembly. Thereby, since the electrode assembly is suppressed from being crushed by the tip of the flange portion, the crush resistance of the electrode assembly can be improved.

  The power storage device includes a sheet provided between the first inner surface and the electrode assembly, and a shortest distance D1 between the front end of the flange portion and the first inner surface is a surface facing the first inner surface of the sheet. The distance may be shorter than the shortest distance D3 between the opposite surface and the first inner surface. In this case, the tip of the flange portion comes into contact with the sheet when pressed to the main body portion side.

  Note that the power storage device may be a secondary battery.

  ADVANTAGE OF THE INVENTION According to this invention, the electrical storage apparatus with which the improvement of the crush tolerance of an electrode assembly was achieved is provided.

It is the schematic which showed a part of internal structure of the secondary battery which concerns on embodiment of this invention. It is sectional drawing along the II-II line of FIG. It is a partial exploded perspective view of the electrode assembly concerning a first embodiment. It is sectional drawing along the IV-IV line of FIG. It is sectional drawing of a part of conventional secondary battery. It is a figure by which the electrode assembly of the conventional secondary battery is pressed by a case. It is a figure by which the electrode assembly of the secondary battery which concerns on this embodiment is pressed by a case. It is a partial exploded perspective view of the electrode assembly in a modification. It is sectional drawing of a part of secondary battery which concerns on a modification.

  Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected about the same or equivalent element, and the description is abbreviate | omitted when description overlaps.

  First, the configuration of the secondary battery 1 as the power storage device according to the present embodiment will be described with reference to FIGS. 1 and 2.

  As shown in FIG. 1, the secondary battery 1 includes a case 10, an electrode assembly 20 accommodated in the case 10, and conductive members 31 and 32 joined to the electrode assembly 20.

  The case 10 includes a can portion and a lid portion made of a metal such as stainless steel or aluminum. The case 10 forms a rectangular parallelepiped sealed space inside. The case 10 is filled with an electrolyte (electrolytic solution) corresponding to the type of the secondary battery 1 such as a lithium ion secondary battery or a nickel hydrogen secondary battery. When the case 10 is made of the above-described metal, the inner peripheral surface of the case 10 may be insulated.

  The electrode assembly 20 includes a main body portion 21, a first current collecting portion 22, and a second current collecting portion 23, and is a portion that stores and supplies power by charging.

  As shown in FIGS. 2 and 3, the electrode assembly 20 is a laminate in which the positive electrodes 24 and the negative electrodes 25 are alternately laminated with the separators S interposed therebetween. The positive electrode 24 includes a rectangular positive electrode metal foil 24a (for example, an aluminum foil) and a positive electrode active material layer 24b provided on both surfaces (surfaces) of the positive electrode metal foil 24a. The positive electrode 24 includes a first active material portion 26 in which a positive electrode active material layer 24b is provided on a positive electrode metal foil 24a, and an uncoated positive electrode in which the positive electrode active material layer 24b is not provided on the positive electrode metal foil 24a. It is comprised from the engineering part 27. In the present embodiment, the positive electrode uncoated portion 27 is provided on one end side in the longitudinal direction of the positive electrode metal foil 24a.

  The negative electrode 25 has a rectangular negative electrode metal foil 25a (for example, copper foil) and a negative electrode active material layer 25b provided on both surfaces (surfaces) of the negative electrode metal foil 25a. The negative electrode 25 includes a second active material portion 28 in which a negative electrode active material layer 25b is provided on a negative electrode metal foil 25a, and a negative electrode that is not provided with a negative electrode active material layer 25b on the negative electrode metal foil 25a. It is comprised from the engineering part 29. FIG. In the present embodiment, the negative electrode uncoated portion 29 is provided on one end side in the longitudinal direction of the negative electrode metal foil 25a.

  The separator S is provided between the positive electrode 24 and the negative electrode 25 and prevents a short circuit between the positive electrode 24 and the negative electrode 25. Specifically, the separator S is provided between the first active material part 26 of the positive electrode 24 and the second active material part 28 of the negative electrode 25. That is, the separator S and the negative electrode 25 are stacked on the first active material portion 26 of the positive electrode 24, and the separator S and the positive electrode 24 are stacked on the second active material portion 28 of the negative electrode 25.

  As described above, the electrode assembly 20 in the present embodiment includes a plurality of positive electrodes 24 and negative electrodes 25, and the positive electrode uncoated portions 27 of the plurality of positive electrodes 24 are respectively arranged on one end side in the longitudinal direction of the positive electrode 24 (or the negative electrode 25). The positive electrode 24 and the negative electrode 25 are laminated so that the negative electrode uncoated portions 29 of the plurality of negative electrodes 25 are respectively disposed on the other end side in the longitudinal direction of the positive electrode 24 (or the negative electrode 25).

  The main body 21 is configured by laminating a first active material part 26, a separator S, and a second active material part 28. The first current collector 22 is configured by laminating a plurality of positive electrode uncoated portions 27 of the positive electrodes 24. Of the positive electrode uncoated portion 27, the positive electrode uncoated portion 27 constituting the first current collector 22 corresponds to the first terminal portion 27a. In addition, in the positive electrode uncoated portion 27, the positive electrode uncoated portion 27 positioned between the first active material portion 26 and the first current collector 22 corresponds to the first connecting portion 27b.

  The second current collector 23 is configured by laminating a plurality of negative electrode uncoated portions 29 of the negative electrodes 25. Of the negative electrode uncoated portion 29, the negative electrode uncoated portion 29 constituting the second current collector 23 corresponds to the second terminal portion 29a. Further, in the negative electrode uncoated portion 29, the negative electrode uncoated portion 29 located between the second active material portion 28 and the second current collecting portion 23 corresponds to the second connecting portion 29b.

  In the present embodiment, the first current collector 22 is provided on one end in the longitudinal direction of the positive electrode 24 (or negative electrode 25), and the second current collector 23 is disposed in the longitudinal direction of the positive electrode 24 (or negative electrode 25). Although it is provided on the other end side, the first current collector 22 and the second current collector 23 are provided anywhere as long as the first current collector 22 and the second current collector 23 are not short-circuited. It may be. In the present embodiment, the active material is not provided in the first connecting portion 27b and the second connecting portion 29b, but an active material may be provided.

  The conductive members 31 and 32 are made of a substantially rectangular metal plate (aluminum plate, copper plate, etc.) having conductivity, and are formed by bending a flat plate of this metal. One end of each of the conductive members 31, 32 is electrically connected to the first current collector 22 and the second current collector 23 of the electrode assembly 20, and the other end is connected to an external terminal (not shown). Yes. The conductive member 31 is disposed on one main surface 22a of the first current collector 22 (one surface of the first current collector 22 that intersects the stacking direction of the positive electrode uncoated portion 27). The conductive members 31 and 32 are welded and electrically connected to the first current collector 22 and the second current collector 23, respectively, by irradiating laser from the lamination direction of the positive electrode uncoated portion 27. Since the conductive members 31 and 32 have the same shape (symmetrical shape), only the conductive member 31 will be described below, and the description of the conductive member 32 will be omitted.

  As shown in FIG. 4, the conductive member 31 includes a base 41 joined to the main surface 22 a of the first current collector 22, and a flat flange portion 42 standing from the end of the base 41 on the main body 21 side. It has. The flange portion 42 is formed by bending the conductive member 31 by press working or the like.

  The flange portion 42 is joined to an end portion of the flange portion 42 opposite to the base portion 41 (hereinafter, the distal end 42 a of the flange portion 42) and the base portion 41 of the first current collector 22 among the inner surface of the case 10. The shortest distance D1 between the first inner surface 10a facing the surface is formed and arranged so as to be shorter than the shortest distance D2 between the positive electrode 24 to which the base 41 of the first current collector 22 is joined and the first inner surface 10a. ing. In the present embodiment, the shortest distance D1 between the edge E on the body portion 21 side at the tip 42a of the flange portion 42 and the first inner surface 10a is the positive electrode active material layer 24b in the first active material portion 26 of the positive electrode 24. The first inner surface 10a is formed and arranged to be shorter than the shortest distance D2.

  A sheet 50 that protects the main body 21 is further disposed in the case 10. The sheet 50 is provided between the main body 21 and the case 10. The sheet 50 is an insulating sheet made of, for example, an organic resin, and is arranged to prevent contact and short circuit between the first inner surface 10 a of the case 10 and the main body 21. Further, the sheet 50 and the first inner surface 10a of the case 10 are in contact with each other without a gap. The shortest distance D1 between the tip 42a of the flange portion 42 and the first inner surface 10a is the surface 50a opposite to the surface facing the first inner surface 10a (the inner surface of the sheet 50) and the first inner surface 10a of the sheet 50. The shortest distance (that is, the thickness of the sheet 50) is shorter than D3. That is, the front end 42 a of the flange portion 42 faces a part of the surface that intersects the extending direction of the seat 50. The thickness D3 of the sheet 50 is 0.1 μm to 3 mm, preferably 0.2 μm to 2 mm, and more preferably 0.3 μm to 1 mm. Note that when the first inner surface 10 a of the case 10 is insulated, the tip 42 a of the flange portion 42 may be in contact with the first inner surface 10 a of the case 10.

  Next, prior to description of the operation of the configuration of the secondary battery 1 according to the first embodiment, the operation of the configuration of the conventional secondary battery 101 will be described with reference to FIGS. 5 and 6.

As shown in FIG. 5, the conventional secondary battery 101 is the same as the secondary battery 1 according to the first embodiment except for the conductive member 131 and the sheet 150. The flange portion 142 formed on the conductive member 131 has a shape that stands vertically from the end portion of the base portion 141 on the main surface 21 side of the first current collecting portion 22 on the main body portion 21 side. That is, the angle θ ₂ formed by the base portion 141 and the flange portion 142 of the conventional secondary battery 101 is a right angle (90 °). The sheet 150 is provided in contact with the entire first inner surface 10a.

  A case where an external force is applied from the side surface of the case 10 in the secondary battery 101 will be described with reference to FIG.

As shown in FIG. 6A, in the case 10, the case 10 is placed on the side surface 10 b facing the end surface opposite to the side where the flange portion 142 of the base portion 141 is provided (hereinafter, the end surface 141 a opposite to the base portion 141). When the force _{F L} toward the inside is added, as shown in (b) of FIG. 6, the first collector section 22 is deformed, the side surface 10b of the case 10 reaches the opposite end surface 141a of the base 141. At the same time, between the first inner surface 10a and the sheet 150 of the case 10, the frictional force corresponding to the force _{F L} (binding) _{F R} acts. This kind of frictional force F _R occurs is because the main body portion 21 is in contact with the casing 10 through the sheet 150.

When the base 141 is further pressed toward the main body 21, the conductive member 131 moves to the main body 21 as shown in FIG. 6C, and the flange 142 is the first connecting portion 27 b of the positive electrode 24. contact with, pressing the first connecting portion 27b with a force _{F C.}

  As a result, stress concentration occurs at the portion of the first connecting portion 27b that contacts the edge E of the tip 142a of the flange portion 142, and the first connecting portion 27b is crushed.

As described above, when the sheets 50 and 150 and the first inner surface 10a of the case 10 and the sheets 50 and 150 and the electrode assembly 20 are in contact with each other with no gap, the vicinity of the case 10 of the electrode assembly 20 is a frictional force. greatly influenced by the F _R. Therefore, the vicinity of the portion of the electrode assembly 20 that is directly or indirectly in contact with the case 10 has a lower tolerance for plastic deformation than the vicinity of the center of the electrode assembly 20.

On the other hand, in the secondary battery 1 according to the first embodiment, as shown in FIG. 7A, in the case 10, the end surface (hereinafter referred to as the side surface) opposite to the side on which the flange portion 42 of the base 41 is provided. the opposite end face 41a) and the opposite sides 10b of the base 41, the force F _L toward the inner case 10 is added, as shown in FIG. 7 (b), so that first current collector 22 is contracted The side surface 10b of the case 10 reaches the opposite end surface 41a of the base 41. When the base 41 is pressed toward the main body 21, the conductive member 31 moves toward the main body 21 as shown in FIG. 7C, and the tip 42 a of the flange 42 contacts the sheet 50. Touch. Thereby, even if the base 41 is further pressed toward the main body 21, the movement of the conductive member 31 toward the main body 21 is suppressed by the sheet 50. Even if the flange portion 42 comes into contact with the first connecting portion 27b, the edge E of the tip 42a of the flange portion 42 does not contact the positive electrode 24. Therefore, the edge of the tip 42a of the flange portion 42 that is the most stress-concentrated portion. E prevents the electrode assembly 20 from being crushed. Accordingly, the crush resistance of the electrode assembly 20 can be improved.

  In the secondary battery 1 according to the first embodiment described above, the shortest distance D1 between the tip 42a of the flange portion 42 and the first inner surface 10a is the positive electrode 24 to which the base portion 41 is joined and the first inner surface 10a. Therefore, even when the conductive member 31 is pressed toward the main body portion 21 and the flange portion 42 contacts the main body portion 21, the tip 42 a of the flange portion 42 is in contact with the positive electrode 24. do not do. As a result, the electrode assembly 20 is prevented from being crushed by the edge E of the tip 42a of the flange portion 42, which is the most stress-concentrated portion, and thus the crush resistance of the electrode assembly 20 is improved.

  Further, the secondary battery 1 has a sheet 50 provided between the first inner surface 10a and the electrode assembly 20, and the shortest distance D1 between the tip 42a of the flange portion 42 and the first inner surface 10a is a sheet. 50, which is shorter than the shortest distance D3 between the surface 50a opposite to the surface facing the first inner surface 10a and the first inner surface 10a. For this reason, the edge E of the front-end | tip 42a of the flange part 42 will contact the sheet | seat 50, if it presses on the main-body part 21 side.

  In addition, this invention is not restricted to the said embodiment, Various deformation | transformation are possible. For example, as shown in FIG. 8, the positive electrode uncoated portion 27 and the negative electrode uncoated portion 29 in the electrode assembly 20 may be tab-shaped. Of the tab-shaped positive electrode uncoated portion 27, the positive electrode uncoated portion 27 constituting the first current collector 22 corresponds to the first terminal portion 27c, and the first active material portion 26 and the first current collector. The positive electrode uncoated portion 27 positioned between the first connecting portion 27 and the second connecting portion 27d corresponds to the first connecting portion 27d. Of the tab-shaped negative electrode uncoated portion 29, the negative electrode uncoated portion 29 constituting the second current collector 23 corresponds to the second terminal portion 29c, and the second active material portion 28 and the second current collector The negative electrode uncoated portion 29 positioned between the portion 23 corresponds to the second connecting portion 29d. The tab-shaped first current collector 22 (second current collector 23) may be formed by laminating a plurality of first terminal portions 27c (a plurality of second terminal portions 29c), or a plurality of tab-shaped first current collectors 22 (second current collectors 23). The first terminal portion 27c (a plurality of second terminal portions 29c) may be formed from one layer.

  For example, as shown in FIG. 9, the conductive member 31 </ b> A may be provided on one main surface 22 a of the first current collector 22, and the conductive member 31 </ b> B may be provided on the other main surface 22 b of the first current collector 22. Good.

  In the above embodiment, the electrode assembly 20 is described as an example of a laminate in which the positive electrode 24 and the negative electrode 25 are laminated via the separator S. A wound body wound so as to overlap with the negative electrode 25 may be used.

  Further, in the above embodiment, the sheet 50 is in direct contact with the case 10, but the sheet 50 may not be in direct contact with the case 10. The electrode assembly 20 may not be in contact with the case 10 and the sheet 50. The power storage device is not limited to a secondary battery such as a lithium ion secondary battery, but may be another power storage device (for example, an electric double layer capacitor, a lithium ion capacitor, or the like).

DESCRIPTION OF SYMBOLS 1,101 ... Secondary battery, 10 ... Case, 10a ... 1st inner surface, 10b ... Side surface, 20 ... Electrode assembly, 21 ... Main-body part, 22 ... 1st current collection part, 22a ... Main surface, 23 ... 2nd Current collecting part, 24 ... positive electrode, 25 ... negative electrode, 26 ... first active material part, 27 ... positive electrode uncoated part, 27b ... first connecting part, 28 ... second active material part, 29 ... negative electrode uncoated part 29b ... second connecting part 31, 31A, 31B, 32, 131 ... conductive member, 41, 141 ... base part, 42, 142 ... flange part, 42a, 142a ... tip, 50, 150 ... sheet, D1-D3 ... the shortest distance, E ... _{edge, F C, F L, F} R ... force, S ... separator.

Claims (3)

A separator provided between a positive electrode and a negative electrode each provided with an active material, a first active material part provided with the positive electrode active material, and a second active material part provided with the negative electrode active material; A power storage device comprising: an electrode assembly including: a conductive member; and a case in which the electrode assembly and the conductive member are accommodated,
The electrode assembly includes:
A main body composed of a portion provided with an active material of the positive electrode, a portion provided with an active material of the negative electrode, and the separator;
A first current collector composed of a portion of the positive electrode where the active material is not provided;
A second current collector formed of a portion of the negative electrode where the active material is not provided;
Have
The positive electrode includes: a first active material portion on which the separator and the negative electrode are stacked; a first terminal portion constituting the first current collector; and the first active material portion and the first terminal portion. A first connecting portion located between
The negative electrode includes: the second active material part on which the separator and the positive electrode are stacked; a second terminal part that constitutes the second current collecting part; and the second active material part and the second terminal part. A second connecting portion located between the two,
The conductive member is erected at a base portion joined to the first current collector or the second current collector, and an end of the base on the main body side, and the first connecting portion or the second Having a flange portion facing the connecting portion at a distance,
The shortest distance D1 between the front end of the flange portion and the first inner surface of the inner surface of the case facing the surface to which the base of the first current collector or the second current collector is joined is the base A power storage device shorter than a shortest distance D2 between the positive electrode or the negative electrode to be joined and the first inner surface. A sheet provided between the first inner surface and the electrode assembly;
The shortest distance D1 between the front end of the flange portion and the first inner surface is shorter than the shortest distance D3 between the surface opposite to the surface facing the first inner surface of the sheet and the first inner surface. The power storage device according to 1.   The power storage device according to claim 1 or 2, wherein the power storage device is a secondary battery.

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