JP2018200755A - Power storage device and manufacturing method thereof - Google Patents

Abstract

To provide a power storage device in which short circuit of electrode assemblies due to a foreign matter can be restrained, without lowering the capacity, and to provide a manufacturing method of power storage device.SOLUTION: A secondary battery 10 includes first and second electrode assemblies 12a, 12b where a positive electrode 30 having a positive electrode active material layer 34, and a negative electrode 31 having a negative electrode active material layer 37 are laminated via a separator 32. The first and second electrode assemblies 12a, 12b have lamination directions matching each other. The secondary battery 10 includes an insulation sheet 50 interposed between the first and second electrode assemblies 12a, 12b adjoining in the lamination direction. Second end faces 23a, 23b of the first and second electrode assemblies 12a, 12b face the insulation sheet 50. The second end face 23a is constituted of the positive electrode 30, and the second end face 23b is constituted of the negative electrode 31. The insulation sheet 50 is thicker than the positive electrode active material layer 34, and the negative electrode active material layer 37, and has a pore structure capable of permeating active material ions.SELECTED DRAWING: Figure 2

Description

  The present invention includes a plurality of electrode assemblies in which a plurality of positive electrodes and negative electrodes each having an active material layer are alternately stacked via separators, and the plurality of electrode assemblies includes a positive electrode and a negative electrode in each electrode assembly. The present invention relates to a power storage device and a method for manufacturing the power storage device that are arranged such that the stacking directions of electrodes and separators coincide with each other.

  Conventionally, vehicles such as EV (Electric Vehicle) and PHV (Plug in Hybrid Vehicle) are mounted with a lithium ion secondary battery or the like as a power storage device that stores electric power supplied to an electric motor or the like. The secondary battery includes an electrode assembly in which a plurality of positive electrodes and negative electrodes having an active material layer are stacked with a separator interposed therebetween, and a metal case that houses the electrode assembly and an electrolytic solution. The secondary battery disclosed in Patent Document 1 includes a plurality of electrode assemblies, and the plurality of electrode assemblies are arranged so that the stacking directions of the positive electrode, the negative electrode, and the separator in each electrode assembly are the same. . The secondary battery includes an insulating member interposed between a pair of electrode assemblies adjacent in the stacking direction. Each of the pair of electrode assemblies includes a facing surface facing the insulating member.

JP 2012-190587 A

  By the way, a part of the active material layer dropped from the positive electrode and the negative electrode is mixed between the opposing surface of the electrode assembly and the insulating member when arranging the plurality of electrode assemblies via the insulating member, It may become a foreign object. If the electrode assembly expands in the stacking direction when the secondary battery is charged, such foreign matter may bite into the insulating member and break through the insulating member. Patent Document 1 does not describe in detail the polarity of the electrode serving as the facing surface. For example, when the facing surface of one electrode assembly is a positive electrode and the facing surface of the other electrode assembly is a negative electrode, mixing is performed. When the insulating member is pierced by the foreign matter, the positive electrode of one electrode assembly and the negative electrode of the other electrode assembly are short-circuited. Further, it is not preferable that the capacity of the secondary battery is reduced by providing the insulating member.

  The present invention has been made to solve the above-described problems, and an object of the present invention is to provide a power storage device and a method for manufacturing the power storage device that can suppress short-circuiting between electrode assemblies due to foreign matters without reducing the capacity. There is.

  A power storage device for solving the above problems includes a plurality of electrode assemblies in which a plurality of sheet-like positive electrodes and negative electrodes each having an active material layer are alternately stacked via separators, and the plurality of electrode assemblies A solid body is a power storage device arranged such that the stacking direction of the positive electrode, the negative electrode, and the separator in each electrode assembly is the same among the plurality of electrode assemblies, and is adjacent to the stacking direction. An insulating sheet interposed between the pair of electrode assemblies is provided, and one end surface of the pair of electrode assemblies that is opposed to the insulating sheet in the one electrode assembly is configured by the positive electrode. The one end surface of the other electrode assembly that faces the insulating sheet is constituted by the negative electrode, and the insulating sheet is thicker than the active material layer of the positive electrode, One said thicker than the active material layer of the negative electrode, ions of the active material is summarized in that having a pore structure capable of transmitting.

  When foreign matter (a part of the active material layer that has fallen off from the positive electrode or the negative electrode) enters between the one end surface of the electrode assembly and the insulating sheet, the electrode assembly in the stacking direction during charging of the power storage device Due to the expansion, the foreign matter bites into the insulating sheet. However, since the thickness of the insulating sheet is thicker than the active material layer of the positive electrode and thicker than the active material layer of the negative electrode, the insulating sheet breaks through any foreign material generated from any active material layer. Is suppressed. Therefore, a short circuit between the electrode assemblies due to foreign matters can be suppressed. In addition, by using an insulating sheet through which ions can permeate, ions can reciprocate between electrode assemblies adjacent in the stacking direction. Therefore, even if an insulating sheet is provided, the capacity of the power storage device does not decrease.

  Further, in the power storage device, the conductive members of each electrode electrically connected to the plurality of electrode assemblies and the tabs protruding from a part of one side of the positive electrode and the negative electrode have the same polarity and the electrodes Preferably, the tab group gathered for each assembly and the tab group gathered for each electrode assembly each include a plurality of welds welded to the conductive member.

  According to this, since the tab groups gathered for each electrode assembly are welded to the conductive members, respectively, the tab groups of all electrode assemblies are welded at one time as compared with the case where the tab groups are collectively welded to the conductive members. The number of tabs is reduced. Therefore, the energy required for one-time welding can be reduced. As a result, for example, an increase in size of the welding apparatus is suppressed.

In the power storage device, the insulating sheet material is preferably the same as the separator material.
According to this, it is not necessary to prepare another material for the insulating sheet.

  In addition, a power storage device that solves the above problem includes a plurality of sheet-like negative electrodes having an active material layer and a plurality of electrode storage separators in which a positive electrode having an active material layer is sandwiched between separator members. A plurality of electrode assemblies, wherein the plurality of electrode assemblies are arranged such that a stacking direction of the negative electrode and the electrode storage separator in each electrode assembly is the same among the plurality of electrode assemblies. A device comprising an insulating sheet interposed between a pair of electrode assemblies adjacent to each other in the stacking direction, and one of the pair of electrode assemblies facing the insulating sheet in one of the electrode assemblies One end surface that is configured by the electrode storage separator, and the other end surface that is the surface facing the insulating sheet in the other electrode assembly is configured by the negative electrode. The thickness of the separator member and the thickness of the insulating sheet is thicker than the active material layer of the positive electrode and thicker than the active material layer of the negative electrode, and the insulating sheet is made of an active material. The gist is to have a pore structure through which ions can permeate.

  When foreign matter (a part of the active material layer that has fallen off from the positive electrode or the negative electrode) enters between the one end surface of the electrode assembly and the insulating sheet, the electrode assembly in the stacking direction during charging of the power storage device Due to the expansion, the foreign matter bites into the separator member and the insulating sheet. However, the total thickness of the separator member and the insulating sheet is thicker than the active material layer of the positive electrode and thicker than the active material layer of the negative electrode. Even if it is the foreign material which was done, it is suppressed that a separator member and an insulating sheet are pierced. Therefore, a short circuit between the electrode assemblies due to foreign matters can be suppressed. In addition, by using an insulating sheet through which ions can permeate, ions can reciprocate between electrode assemblies adjacent in the stacking direction. Therefore, even if an insulating sheet is provided, the capacity of the power storage device does not decrease. Moreover, the thickness of an insulating sheet can be made thin by comprising the thickness of a separator member, and the thickness of an insulating sheet together, compared with the case where thickness is comprised only with one insulating sheet.

  A method for manufacturing a power storage device that solves the above problems includes a first electrode assembly and a second electrode assembly in which a plurality of sheet-like positive electrodes and negative electrodes each having an active material layer are alternately stacked via separators. A first electrode assembly and a second electrode assembly, the first electrode assembly, the negative electrode, and the separator are stacked in the first electrode assembly; and the second electrode A method of manufacturing a power storage device arranged so that a stacking direction of the positive electrode, the negative electrode, and the separator in an assembly coincides, wherein one end surface of the first electrode assembly in the stacking direction is One end surface of the positive electrode and the second electrode assembly in the stacking direction is the negative electrode, and a surface orthogonal to the one end surface of the first electrode assembly and an end surface of the second electrode assembly are orthogonal to each other. Facing each other and facing one end up An insulating sheet having a hole structure that is thicker than the active material layer of the positive electrode and thicker than the active material layer of the negative electrode and is capable of transmitting ions. The first electrode assembly is overlapped with one end surface of the electrode assembly or one end surface of the second electrode assembly, and the one end surfaces of the first electrode assembly and the second electrode assembly are brought close to each other. The gist is to interpose the insulating sheet between one end surface of the solid body and one end surface of the second electrode assembly.

  In such a manufacturing method, when one end surfaces of the first and second electrode assemblies are brought close to each other and an insulating sheet is interposed, foreign matter (part of the active material layer dropped off from the positive electrode or the negative electrode) There is a possibility of contamination between the electrode assemblies. When foreign matter is mixed between one end surface of the first electrode assembly and the insulating sheet and between one end surface of the second electrode assembly and the insulating sheet, the stacking direction of the electrode assemblies during charging of the power storage device Due to the expansion, the foreign material bites into the insulating sheet. However, the thickness of the insulating sheet interposed between the one end surface of the first electrode assembly and the one end surface of the second electrode assembly is made larger than the thickness of the active material layer of the positive electrode, and the active electrode of the negative electrode is activated. By making it thicker than the thickness of the material layer, it is possible to prevent the insulating sheet from being pierced by any foreign material generated from any active material layer. Therefore, even if it is an electrical storage apparatus provided with the 1st and 2nd electrode assembly, the short circuit of the electrode assemblies by a foreign material can be suppressed. In addition, by using an insulating sheet through which ions can permeate, ions can reciprocate between electrode assemblies adjacent in the stacking direction. Therefore, even if an insulating sheet is provided, the capacity of the power storage device does not decrease.

  In the method for manufacturing the power storage device, a surface orthogonal to one end surface of the first electrode assembly is formed from a part of one side of the positive electrode and the negative electrode stacked in the first electrode assembly. A tab side end surface where the first tab group in which the protruding tabs are gathered together with the same polarity exists is provided, and a surface orthogonal to one end surface of the second electrode assembly is laminated in the second electrode assembly. The tabs projecting from a part of one side of the positive electrode and the negative electrode are tab side end surfaces where there is a second tab group in which the tabs are gathered with the same polarity, and one end surface of the first electrode assembly and the The first tab group and the second tab group are preferably welded to the conductive member before the insulating sheet is interposed between the one end surface of the second electrode assembly.

  According to this, by welding the tab group and the conductive member with the tab side end surface of the first electrode assembly and the tab side end surface of the second electrode assembly facing each other, the first and second When one end face of the electrode assembly is brought close to each other and an insulating sheet is interposed, the first tab group is bent toward the second electrode assembly side in the stacking direction, and the second tab group is The tip is bent toward the first electrode assembly in the stacking direction. Therefore, a short circuit between the tab group and the case housing the first and second electrode assemblies can be suppressed. Also, when welding the tab group to the conductive member, the first tab group and the second tab group are separately performed, so that both the first tab group and the second tab group are welded together. The number of tabs to be welded at a time is reduced. Therefore, the energy required for one-time welding can be reduced. As a result, for example, an increase in size of the welding apparatus is suppressed.

  According to the present invention, it is possible to suppress a short circuit between electrode assemblies due to a foreign substance without reducing the capacity.

The disassembled perspective view of the secondary battery of embodiment. (A) is sectional drawing of the secondary battery of embodiment, (b) is an enlarged view of (a). (A), (b) is a perspective view which shows the manufacturing method of a secondary battery typically. (A) is sectional drawing of the secondary battery of another example, (b) is an enlarged view of (a).

Hereinafter, an embodiment in which the power storage device is embodied as a secondary battery will be described with reference to FIGS.
As shown in FIGS. 1 and 2A, the secondary battery 10 as a power storage device includes a case 11. The secondary battery 10 includes a first electrode assembly 12a as an electrode assembly housed in a case 11, a second electrode assembly 12b as an electrode assembly, and an electrolyte (not shown). . The case 11 includes a rectangular parallelepiped case main body 13 and a rectangular flat lid 14 that closes the opening 13 a of the case main body 13. Both the case main body 13 and the lid 14 constituting the case 11 are made of metal (for example, stainless steel or aluminum). Further, the secondary battery 10 of the present embodiment is a prismatic battery whose appearance is square. Further, the secondary battery 10 of the present embodiment is a lithium ion battery.

  The case main body 13 includes a rectangular plate-like bottom wall 13b and first to fourth wall portions 13c to 13f that are erected from the periphery of the bottom wall 13b. The case body 13 includes a first wall portion 13c on one of the wall portions connected to the pair of long edges of the bottom wall 13b, and a second wall on the other wall portion facing the first wall portion 13c. A portion 13d is provided. The case main body 13 includes a third wall portion 13e on one of the wall portions connecting the first wall portion 13c and the second wall portion 13d and connecting to the pair of short edge portions of the bottom wall 13b. The other wall portion facing the third wall portion 13e is provided with a fourth wall portion 13f.

  The secondary battery 10 includes a positive electrode terminal 15 and a negative electrode terminal 16 for taking out electricity from the first and second electrode assemblies 12a and 12b. The positive electrode terminal 15 and the negative electrode terminal 16 penetrate the through hole 14 a of the lid 14 and protrude out of the case 11. A ring-shaped insulating ring 17 for insulating from the lid 14 is attached to the positive terminal 15 and the negative terminal 16, respectively. The secondary battery 10 includes a positive electrode conductive member 15 a as a rectangular plate-shaped conductive member in the case 11. The secondary battery 10 includes a negative electrode conductive member 16 a as a rectangular plate-shaped conductive member in the case 11. The positive electrode terminal 15 is electrically connected to the positive electrode conductive member 15a, and the negative electrode terminal 16 is electrically connected to the negative electrode conductive member 16a.

  The first electrode assembly 12 a and the second electrode assembly 12 b include a plurality of sheet-like positive electrodes 30, a plurality of sheet-like negative electrodes 31, and a plurality of sheet-like separators 32. The first electrode assembly 12 a and the second electrode assembly 12 b have a structure in which a separator 32 is interposed between the positive electrode 30 and the negative electrode 31 and are laminated in a state of being insulated from each other.

  In the first electrode assembly 12a, the direction in which the positive electrode 30, the negative electrode 31, and the separator 32 are stacked is a first stacking direction. In the second electrode assembly 12b, the positive electrode 30, the negative electrode 31, The direction in which the separators 32 are stacked is defined as a second stacking direction. The 1st electrode assembly 12a and the 2nd electrode assembly 12b are arrange | positioned so that a 1st lamination direction and a 2nd lamination direction may correspond. Hereinafter, the first stacking direction and the second stacking direction are simply referred to as a stacking direction. Moreover, let the dimension in a lamination direction be thickness.

  The positive electrode 30 includes a rectangular sheet-like positive electrode metal foil (for example, an aluminum foil) 33 and a positive electrode active material layer 34 as an active material layer present on both surfaces of the positive electrode metal foil 33. The positive electrode 30 includes a first edge 30a on one edge of the edges along the pair of long sides. The positive electrode 30 has a positive electrode tab 35 as a tab protruding from a part of the first edge 30a. The positive electrode tab 35 is composed of the positive electrode metal foil 33 itself without the positive electrode active material layer 34. The direction in which the positive electrode tab 35 protrudes from the first edge 30 a of the positive electrode 30 is defined as the protruding direction of the positive electrode tab 35.

  As shown in FIG. 2A and FIG. 2B, the negative electrode 31 includes a rectangular sheet-like negative electrode metal foil (for example, copper foil) 36 and active material layers existing on both sides of the negative electrode metal foil 36. A negative electrode active material layer 37. The thickness H37 of the negative electrode active material layer 37 is thinner than the thickness H34 of the positive electrode active material layer. In other words, the thickness H34 of the positive electrode active material layer 34 is thicker than the thickness H37 of the negative electrode active material layer 37. The negative electrode 31 includes a first edge portion 31a on one edge portion of the edge portions along the pair of long sides. The negative electrode 31 has a negative electrode tab 38 as a tab protruding from a part of the first edge portion 31a. The negative electrode tab 38 is composed of the negative electrode metal foil 36 itself without the negative electrode active material layer 37. The direction in which the negative electrode tab 38 protrudes from the first edge 31 a of the negative electrode 31 is defined as the protruding direction of the negative electrode tab 38. The protruding direction of the negative electrode tab 38 coincides with the protruding direction of the positive electrode tab 35. In the present embodiment, the outer shape of the negative electrode 31 viewed from the stacking direction is also slightly larger than the outer shape of the positive electrode 30 viewed from the stacking direction.

  The separator 32 is made of polypropylene (PP). The separator 32 has a fine pore structure so that the lithium ion (ion) of the positive electrode active material can pass along with charge / discharge of the secondary battery 10. The thickness H32 of the separator 32 is thicker than the thickness H34 of the positive electrode active material layer 34 and thicker than the thickness H37 of the negative electrode active material layer 37. In the present embodiment, the outer shape of the separator 32 as viewed from the stacking direction is the same size as that of the negative electrode 31 as viewed from the stacking direction, and is slightly larger than the outer shape of the positive electrode 30.

  As shown in FIG. 1, in the first and second electrode assemblies 12a and 12b, the plurality of positive electrodes 30 are stacked such that the respective positive electrode tabs 35 are arranged in a line along the stacking direction. . Similarly, in the first and second electrode assemblies 12a and 12b, the plurality of negative electrodes 31 are arranged in a row along the stacking direction at positions where the respective negative electrode tabs 38 do not overlap with the positive electrode tabs 35. Are laminated.

  The positive electrode tabs 35 are gathered together at one end in the stacking direction to form a positive electrode tab group 18 as a tab group. Similarly, the negative electrode tabs 38 are gathered together at one end in the stacking direction to form a negative electrode tab group 19 as a tab group. The positive electrode tab group 18 and the negative electrode tab group 19 include a proximal-side bent portion 41 that is bent from one end to the other end in the stacking direction on the proximal end side in the protruding direction of the positive electrode tab 35 and the negative electrode tab 38. Further, the positive electrode tab group 18 and the negative electrode tab group 19 include an extending portion 42 that extends from the proximal end side bent portion 41 in the stacking direction. The positive electrode tab group 18 of the first electrode assembly 12a is referred to as a first positive electrode tab group 18a, and the positive electrode tab group 18 of the second electrode assembly 12b is referred to as a second positive electrode tab group 18b. Similarly, the negative electrode tab group 19 of the first electrode assembly 12a is referred to as a first negative electrode tab group 19a, and the negative electrode tab group 19 of the second electrode assembly 12b is referred to as a second negative electrode tab group 19b.

  As shown in FIG. 3A and FIG. 3B, the secondary battery 10 includes a welded portion in which the extended portion 42 of the first positive electrode tab group 18a and the positive electrode conductive member 15a are welded and joined. The first welded portion 61, the extended portion 42 of the second positive electrode tab group 18 b and the positive electrode conductive member 15 a are welded and joined as a second welded portion 62 as a welded portion. Further, the secondary battery 10 includes a third welded portion 63 as a welded portion in which the extending portion 42 of the first negative electrode tab group 19a and the negative electrode conductive member 16a are welded and joined, and a second negative electrode tab group. The extended part 42 of 19b and the negative electrode electrically-conductive member 16a are equipped with the 4th welding part 64 as a welding part joined by welding.

  As shown in FIG. 1, the first electrode assembly 12 a includes a tab-side end surface 20 a on an end surface where the first positive electrode tab group 18 a and the first negative electrode tab group 19 a exist, and a bottom wall 13 b of the case body 13. A bottom-side end surface 21a is provided on the end surface opposite to the inner surface. The first electrode assembly 12a includes a first end surface 22a on an end surface facing the inner surface of the first wall portion 13c of the case body 13, and a first end surface as an end surface on the end surface paired with the first end surface 22a in the stacking direction. Two end surfaces 23a are provided. The 1st end surface 22a is comprised by the negative electrode 31 located in the end of the lamination direction. The 2nd end surface 23a is comprised by the negative electrode 31 located in the other end of the lamination direction. The second end surface 23a is a facing surface that faces an insulating sheet 50 described later in the first electrode assembly 12a. The first electrode assembly 12a includes a third end surface 24a on an end surface of the case main body 13 facing the inner surfaces of the third wall portion 13e and the fourth wall portion 13f. The tab side end surface 20a, the bottom side end surface 21a, and the third end surface 24a are surfaces orthogonal to the second end surface 23a.

  The second electrode assembly 12b includes a tab-side end surface 20b on an end surface where the second positive electrode tab group 18b and the second negative electrode tab group 19b exist, and an end surface opposite to the inner surface of the bottom wall 13b of the case body 13. A bottom end face 21b is provided. The second electrode assembly 12b includes a first end surface 22b on an end surface facing the inner surface of the second wall portion 13d of the case body 13, and a first end surface as an end surface on the end surface paired with the first end surface 22b in the stacking direction. Two end surfaces 23b are provided. The 1st end surface 22b is comprised by the negative electrode 31 located in the end of the lamination direction. The 2nd end surface 23b is comprised by the positive electrode 30 located in the other end of the lamination direction. The second end surface 23b is a facing surface that faces an insulating sheet 50 described later in the second electrode assembly 12b. The second electrode assembly 12b includes a third end surface 24b on an end surface facing the inner surfaces of the third wall portion 13e and the fourth wall portion 13f of the case body 13. The tab side end surface 20b, the bottom side end surface 21b, and the third end surface 24b are end surfaces orthogonal to the second end surface 23b.

  The secondary battery 10 is interposed between the positive electrode 30 constituting the second end face 23a of the first electrode assembly 12a and the negative electrode 31 constituting the second end face 23b of the second electrode assembly 12b. An insulating sheet 50 is provided. The insulating sheet 50 insulates the second end surface 23a of the first electrode assembly 12a from the second end surface 23b of the second electrode assembly 12b. The material and shape of the insulating sheet 50 of the present embodiment are the same as the material and shape of the separator 32 described above. That is, the insulating sheet 50 is made of polypropylene (PP) and has a fine pore structure so that lithium ions (ions) of the positive electrode active material can pass through with charge / discharge. Moreover, the thickness H50 of the insulating sheet 50 is thicker than the thickness H34 of the positive electrode active material layer 34 and thicker than the thickness H37 of the negative electrode active material layer 37 (see FIG. 2B).

  The secondary battery 10 includes an insulating film 51 (not shown in FIG. 1) that covers the first electrode assembly 12a and the second electrode assembly 12b. The insulating film 51 is made of, for example, polypropylene (PP). The insulating film 51 is formed in a bag shape by folding and welding one insulating film. The insulating film 51 covers the bottom end surfaces 21a and 21b, the first end surfaces 22a and 22b, and the third end surfaces 24a and 24b of the first and second electrode assemblies 12a and 12b. The insulating film 51 insulates the bottom-side end surfaces 21 a and 21 b of the first and second electrode assemblies 12 a and 12 b from the bottom wall 13 b of the case body 13. The insulating film 51 insulates the first end surface 22a of the first electrode assembly 12a from the first wall portion 13c of the case main body 13, and the first end surface 22b of the second electrode assembly 12b and the first end surface 22b of the case main body 13 from the first electrode assembly 12a. Two walls 13d are insulated. The insulating film 51 insulates the third end surfaces 24 a and 24 b of the first and second electrode assemblies 12 a and 12 b from the third and fourth wall portions 13 e and 13 f of the case body 13.

Next, the arrangement | positioning process of the 1st electrode assembly 12a and the 2nd electrode assembly 12b which is a part of manufacturing process of the secondary battery 10 is demonstrated.
First, as shown in FIG. 3A, the first electrode assembly 12a, the second electrode assembly 12b, the positive electrode conductive member 15a, and the negative electrode conductive member 16a are arranged on a work table (not shown). . At this time, the tab-side end surface 20a of the first electrode assembly 12a and the tab-side end surface 20b of the second electrode assembly 12b are opposed to each other, and the second end surface 23a of the first electrode assembly 12a and the second electrode The second end face 23b of the assembly 12b is provided side by side. The second end faces 23a and 23b are positioned on the upper side in the vertical direction and constitute the upper surfaces of the first and second electrode assemblies 12a and 12b. The first end surfaces 22a and 22b are in contact with the work table. In addition, the first positive electrode tab group 18a is disposed so as to overlap with a portion located on one side in the longitudinal direction of the positive electrode conductive member 15a, and the first negative electrode tab group 19a is located on one side in the longitudinal direction of the negative electrode conductive member 16a. Place it on top of the other. Similarly, the second positive electrode tab group 18b is disposed so as to overlap with a portion located on one side of the positive electrode conductive member 15a in the longitudinal direction, and the second negative electrode tab group 19b is located on one side of the negative electrode conductive member 16a in the longitudinal direction. Place it over the site. The front end of the first positive electrode tab group 18a and the front end of the second positive electrode tab group 18b face each other with a gap in the short direction of the positive electrode conductive member 15a. Similarly, the tip of the first negative electrode tab group 19a and the tip of the second negative electrode tab group 19b face each other with a gap in the short direction of the negative electrode conductive member 16a.

  Next, the first positive electrode tab group 18a is welded and joined to the positive electrode conductive member 15a, and the first negative electrode tab group 19a is welded and joined to the negative electrode conductive member 16a. Thereby, the 1st welding part 61 and the 3rd welding part 63 are formed. Similarly, the second positive electrode tab group 18b is welded and joined to the positive electrode conductive member 15a, and the second negative electrode tab group 19b is welded and joined to the negative electrode conductive member 16a. Thereby, the 2nd welding part 62 and the 4th welding part 64 are formed. Then, the insulating sheet 50 is placed on the second end face 23b of the second electrode assembly 12b.

  Thereafter, as shown in FIG. 3 (b), the first and second end surfaces 23a of the first electrode assembly 12a and the second end surface 23b of the second electrode assembly 12b approach each other. The positive electrode tab groups 18a and 18b and the first and second negative electrode tab groups 19a and 19b are bent, and the second end surface 23a of the first electrode assembly 12a and the second end surface 23b of the second electrode assembly 12b are formed. It is made to oppose through the insulating sheet 50. As a result, the base end side bent portion 41 and the extending portion 42 are formed in the first and second positive electrode tab groups 18a and 18b and the first and second negative electrode tab groups 19a and 19b.

Next, the effect of this embodiment will be described together with the action.
(1) The foreign matter (a part of the positive electrode active material layer 34 or the negative electrode active material layer 37 dropped from the positive electrode 30 or the negative electrode 31) is removed from the second end surfaces 23a of the first and second electrode assemblies 12a and 12b. When the insulating sheet 50 is interposed with the 23b close to each other, it may be mixed between the first and second electrode assemblies 12a and 12b. When foreign matter enters between the second end face 23a of the first electrode assembly 12a and the insulating sheet 50 or between the second end face 23b of the second electrode assembly 12b and the insulating sheet 50, the secondary battery 10 Due to the expansion of the first and second electrode assemblies 12a and 12b in the stacking direction during charging, foreign matter bites into the insulating sheet 50. However, since the thickness H50 of the insulating sheet 50 is thicker than the thickness H34 of the positive electrode active material layer 34 and thicker than the thickness H37 of the negative electrode active material layer 37, the foreign material generated from any active material layer is not limited to the insulating sheet 50. Is prevented from being broken through. Therefore, even if it is the secondary battery 10 provided with the 1st and 2nd electrode assemblies 12a and 12b, the short circuit of the 1st electrode assembly 12a and the 2nd electrode assembly 12b by a foreign material can be suppressed. In addition, by using the insulating sheet 50 through which lithium ions can pass, lithium ions can reciprocate between the first electrode assembly 12a and the second electrode assembly 12b. Even if provided, the capacity of the secondary battery 10 does not decrease.

  (2) When the first and second positive electrode tab groups 18a and 18b are welded to the positive electrode conductive member 15a, the first positive electrode tab group 18a and the second positive electrode tab group 18b are divided into two portions. For this reason, compared with the case where the 1st positive electrode tab group 18a and the 2nd positive electrode tab group 18b are welded together, the number of the positive electrode tabs 35 welded at a time decreases. Similarly, when the first and second negative electrode tab groups 19a and 19b are welded to the negative electrode conductive member 16a, the first negative electrode tab group 19a and the second negative electrode tab group 19b are divided into two portions. For this reason, compared with the case where the 1st negative electrode tab group 19a and the 2nd negative electrode tab group 19b are welded together, the number of the negative electrode tabs 38 welded at a time decreases. Therefore, the energy required for one-time welding can be reduced. As a result, for example, an increase in size of the welding apparatus is suppressed.

(3) Since the material of the insulating sheet 50 is the same as the material of the separator 32, it is not necessary to prepare another material for the insulating sheet 50.
(4) With the tab side end surface 20a of the first electrode assembly 12a and the tab side end surface 20b of the second electrode assembly 12b facing each other, the first and second positive electrode tab groups 18a and 18b are set to be positive electrodes. By welding to the conductive member 15a, the first positive electrode tab group 18a is bent toward the second electrode assembly 12b in the stacking direction, and the second positive electrode tab group 18b has the front end in the stacking direction. Are bent toward the first electrode assembly 12a side. Therefore, it is possible to suppress a short circuit between the first and second positive electrode tab groups 18a and 18b and the inner surface of the case body 13 that houses the first and second electrode assemblies 12a and 12b. Similarly, a short circuit between the first and second negative electrode tab groups 19 a and 19 b and the inner surface of the case body 13 can be suppressed.

In addition, you may change the said embodiment as follows.
The secondary battery 10 includes two electrode assemblies, but may include three or more electrode assemblies. In this case, for a pair of electrode assemblies adjacent in the stacking direction, the insulating sheet 50 is interposed between the end surface in the stacking direction of one electrode assembly and the end surface in the stacking direction of the other electrode assembly.

  The positive electrode 30 may have a structure in which the positive electrode active material layer 34 exists on one side of the positive electrode metal foil 33. Similarly, the negative electrode 31 may have a structure in which the negative electrode active material layer 37 exists on one surface of the negative electrode metal foil 36.

The thickness H37 of the negative electrode active material layer 37 may be the same as the thickness H34 of the positive electrode active material layer 34, or may be thicker than the thickness H34 of the positive electrode active material layer 34.
The second end face 23 a of the first electrode assembly 12 a may be constituted by the positive electrode 30, and the second end face 23 b of the second electrode assembly 12 b may be constituted by the negative electrode 31. That is, the polarity of the electrode constituting the second end face 23a of the first electrode assembly 12a and the polarity of the electrode constituting the second end face 23b of the second electrode assembly 12b may be different.

  The first and second electrode assemblies 12a and 12b have a structure in which a plurality of positive electrodes 30 and a plurality of negative electrodes 31 are alternately stacked via separators 32, but the structure of the electrode assemblies is this. It is not limited to.

  For example, as shown in FIGS. 4A and 4B, the first and second electrode assemblies 12 c and 12 d include a bag-shaped electrode storage separator 72 that stores the positive electrode 30, a negative electrode 31, and the like. The structure which laminated | stacked alternately may be sufficient. The electrode storage separator 72 includes a first separator member 73 and a second separator member 74 as rectangular sheet-like separator members. The first and second separator members 73 and 74 are made of, for example, polypropylene (PP). The thickness H73 and the shape of the first separator member 73 are the same as the thickness H74 and the shape of the second separator member 74. Similarly, the outer shape of the first and second separator members 73 and 74 viewed from the stacking direction is slightly larger than the outer shape of the positive electrode 30 viewed from the stacking direction. The first and second separator members 73, 74 protrude from the edge of the positive electrode 30 in a state where the positive electrode 30 is sandwiched between the first separator member 73 and the second separator member 74. Is provided. The electrode storage separator 72 is formed in a bag shape by joining the protruding portion 73 a of the first separator member 73 and the protruding portion 74 a of the second separator member 74. Although not shown, the positive electrode tab 35 of the positive electrode 30 is not stored in the electrode storage separator 72 but protrudes from the electrode storage separator 72.

  In this case, the second end surface 23 c of the first electrode assembly 12 c is configured by the negative electrode 31, and the second end surface 23 d of the second electrode assembly 12 d is configured by the electrode storage separator 72 that stores the positive electrode 30. Yes. An insulating sheet 52 is interposed between the second end surface 23c of the first electrode assembly 12c and the second end surface 23d of the second electrode assembly 12d.

  The electrode storage separator 72 and the insulating sheet 52 are made of polypropylene (PP), and have a fine pore structure so that lithium ions (ions) of the positive electrode active material can pass along with charge / discharge of the secondary battery 10. Have. A thickness H obtained by adding the thickness H73 of the first separator member 73 and the thickness H52 of the insulating sheet 52 is thicker than the thickness H34 of the positive electrode active material layer 34 and thicker than the thickness H37 of the negative electrode active material layer 37.

  As a result, foreign matter (a part of the positive electrode active material layer 34 or the negative electrode active material layer 37 that has fallen off from the positive electrode 30 or the negative electrode 31) is formed between the second end face 23c of the first electrode assembly 12c and the insulating sheet 52. When the secondary battery 10 is charged, the first and second electrode assemblies 12a and 12b are stacked when the secondary battery 10 is mixed between the second end face 23d of the second electrode assembly 12d and the first separator member 73. Due to the expansion in the direction, the foreign matter bites into the insulating sheet 52 and the first separator member 73. However, since the thickness H, which is the sum of the thickness H73 of the first separator member 73 and the thickness H52 of the insulating sheet 52, is thicker than the thickness H34 of the positive electrode active material layer 34 and thicker than the thickness H37 of the negative electrode active material layer 37, The foreign material generated from any active material layer is prevented from breaking through the insulating sheet 50 and the first separator member 73. Therefore, a short circuit between the first electrode assembly 12c and the second electrode assembly 12d due to foreign matter can be suppressed.

  Further, by using the insulating sheet 52 that is permeable to lithium ions, the lithium ions can reciprocate between the first electrode assembly 12c and the second electrode assembly 12d, and the insulating sheet 52 is provided. However, the capacity of the secondary battery 10 does not decrease.

  In addition, the thickness H33 of the first separator member 73 and the thickness H52 of the insulating sheet 52 are added to form the thickness H, so that the insulating sheet is compared with the case where the thickness H is configured by only one insulating sheet 52. The thickness H52 of 52 can be reduced.

  (Circle) the material of the separator 32 and the insulating sheet 50 may be changed suitably. In the above embodiment, the material of the insulating sheet 50 may be different from the material of the separator 32. However, the thickness H50 of the insulating sheet 50 is thicker than the thickness H34 of the positive electrode active material layer 34 and thicker than the thickness H37 of the negative electrode active material layer 37, and the sheet has a hole structure that allows lithium ions to pass therethrough. . In addition, a plurality of insulating sheets 50 may be stacked to make the total thickness of the insulating sheets 50 thicker than the thickness H34 of the positive electrode active material layer 34 and thicker than the thickness H37 of the negative electrode active material layer 37.

  In the arrangement process of the above embodiment, when the second end surface 23a of the first electrode assembly 12a and the second end surface 23b of the second electrode assembly 12b are arranged side by side, the first electrode assembly 12a The tab side end surfaces 20a and 20b are opposed to each other, but other end surfaces (bottom side end surfaces 21a and 21b and third end surfaces 24a and 24b) orthogonal to the second end surface 23b may be opposed to each other. In this case, the second end surface 23a of the first electrode assembly 12a and the second end surface 23b of the second electrode assembly 12b are brought close to each other, so that the second end surface 23a of the first electrode assembly 12a and the second end surface 23b After interposing the insulating sheet 50 between the second end face 23b of the electrode assembly 12b, the first and second positive electrode tab groups 18a and 18b are welded and joined to the positive electrode conductive member 15a. The second negative electrode tab groups 19a and 19b are welded and joined to the negative electrode conductive member 16a.

  ○ After the insulating sheet 50 is placed over the second end surface 23a of the first electrode assembly 12a, the second end surface 23a of the first electrode assembly 12a and the second end surface 23b of the second electrode assembly 12b And the insulating sheet 50 may be interposed between the second end surface 23a of the first electrode assembly 12a and the second end surface 23b of the second electrode assembly 12b.

  O Both the first and second positive electrode tab groups 18a and 18b may be welded together to the positive electrode conductive member 15a. Similarly, both the first and second negative electrode tab groups 19a and 19b may be welded together to the negative electrode conductive member 16a.

  The secondary battery 10 may be a lithium ion secondary battery or another secondary battery. In short, any ion may be used as long as ions move between the active material for the positive electrode and the active material for the negative electrode and charge is transferred.

  The power storage device can also be applied to power storage devices other than secondary batteries, such as capacitors.

  DESCRIPTION OF SYMBOLS 10 ... Secondary battery as an electrical storage device, 12a ... 1st electrode assembly as an electrode assembly, 12b ... 2nd electrode assembly as an electrode assembly, 15a ... Positive electrode conductive member as a conductive member, 16a ... Negative electrode conductive member as a conductive member, 18a ... First positive electrode tab group as a tab group, 18b ... Second positive electrode tab group as a tab group, 19a ... First negative electrode tab group as a tab group, 19b ... Tab 2nd negative electrode tab group as a group, 23a, 23b ... 2nd end surface as one end surface, 30 ... Positive electrode, 31 ... Negative electrode, 32 ... Separator, 34 ... Positive electrode active material layer as active material layer, 35 ... Positive electrode tab as a tab, 37 ... Negative electrode active material layer as an active material layer, 38 ... Negative electrode tab as a tab, 72 ... Electrode storage separator, 73 ... First separator as a separator member, 74 ... Separator member Second separator, 50, 52: insulating sheet, the first to fourth weld as 61 to 64 ... weld Te.

Claims (6)

A plurality of electrode assemblies in which a plurality of sheet-like positive electrodes and negative electrodes having an active material layer are alternately stacked via separators,
The plurality of electrode assemblies are power storage devices arranged such that a stacking direction of the positive electrode, the negative electrode, and the separator in each electrode assembly is the same among the plurality of electrode assemblies,
An insulating sheet interposed between a pair of the electrode assemblies adjacent in the stacking direction;
Of the pair of electrode assemblies, one end surface of the one electrode assembly, which is a surface facing the insulating sheet, is configured by the positive electrode, and the other electrode assembly is facing the insulating sheet. One end surface is configured by the negative electrode,
The power storage device, wherein the insulating sheet is thicker than the active material layer of the positive electrode and thicker than the active material layer of the negative electrode, and has a hole structure through which ions of the active material can pass. A conductive member of each electrode electrically connected to the plurality of electrode assemblies;
A tab group in which tabs protruding from a part of one side of the positive electrode and the negative electrode are gathered together for each of the electrode assemblies with the same polarity,
Each of the tab groups gathered together for each electrode assembly, a plurality of welds welded to the conductive member,
The power storage device according to claim 1.   The power storage device according to claim 1, wherein a material of the insulating sheet is the same as a material of the separator. A plurality of electrode assemblies in which a plurality of sheet-like negative electrodes having an active material layer and a plurality of electrode storage separators each having a positive electrode having an active material layer sandwiched between separator members are stacked;
The plurality of electrode assemblies are power storage devices arranged such that a stacking direction of the negative electrode and the electrode storage separator in each electrode assembly is the same among the plurality of electrode assemblies,
An insulating sheet interposed between a pair of the electrode assemblies adjacent in the stacking direction;
Of the pair of electrode assemblies, one end surface of the one electrode assembly, which is a surface facing the insulating sheet, is configured by the electrode storage separator, and the other electrode assembly is opposed to the insulating sheet. One end surface to be a surface is constituted by the negative electrode,
The combined thickness of the separator member and the insulating sheet is thicker than the active material layer of the positive electrode and thicker than the active material layer of the negative electrode,
The power storage device, wherein the insulating sheet has a hole structure through which ions of an active material can pass. Comprising a first electrode assembly and a second electrode assembly in which a plurality of sheet-like positive electrodes and negative electrodes having an active material layer are alternately laminated via separators;
The first electrode assembly and the second electrode assembly include a stacking direction of the positive electrode, the negative electrode, and the separator in the first electrode assembly, and the second electrode assembly. A method of manufacturing a power storage device arranged such that the positive electrode, the negative electrode, and the separator stacking direction coincide with each other,
One end surface of the first electrode assembly in the stacking direction is the positive electrode, and one end surface of the second electrode assembly in the stacking direction is the negative electrode, and is orthogonal to the one end surface of the first electrode assembly. The surface and a surface orthogonal to one end surface of the second electrode assembly are opposed to each other, and both one end surfaces are positioned on the upper surface,
An insulating sheet having a pore structure that is thicker than the active material layer of the positive electrode and thicker than the active material layer of the negative electrode and is permeable to ions, one end surface of the first electrode assembly, Or overlaid on one end surface of the second electrode assembly,
One end surfaces of the first electrode assembly and the second electrode assembly are brought close to each other, and the insulation is provided between one end surface of the first electrode assembly and one end surface of the second electrode assembly. A method for manufacturing a power storage device, wherein a sheet is interposed. A surface orthogonal to one end surface of the first electrode assembly is gathered with tabs protruding from a part of one side of the positive electrode and the negative electrode stacked in the first electrode assembly with the same polarity. The tab side end surface where the first tab group exists,
A surface perpendicular to one end surface of the second electrode assembly is gathered with tabs protruding from a part of one side of the positive electrode and the negative electrode stacked in the second electrode assembly with the same polarity. A tab side end surface on which the second tab group exists,
Before interposing the insulating sheet between one end surface of the first electrode assembly and one end surface of the second electrode assembly, the first tab group and the second tab group are electrically conductive members. The manufacturing method of the electrical storage apparatus of Claim 5 welded to.