JP6079592B2 - Power storage device - Google Patents

Description

  The present invention relates to a power storage device including an electrode assembly housed in a case.

  A vehicle such as an EV (Electric Vehicle) or a PHV (Plug in Hybrid Vehicle) is equipped with a secondary battery such as a lithium ion battery as a power storage device that stores power supplied to an electric motor serving as a prime mover. This type of secondary battery is disclosed in Patent Document 1, for example.

  As shown in FIG. 14, the secondary battery 100 of Patent Document 1 is configured by housing an electrode assembly 102 in a case 101 and connecting a terminal member 103 to the electrode assembly 102. The electrode assembly 102 includes a negative electrode 104 obtained by applying a negative electrode active material layer 104b to a metal foil 104a, and a positive electrode 105 obtained by applying a positive electrode active material layer 105b to a metal foil 105a. The electrode assembly 102 is formed in a layered manner with a separator 106 interposed between the negative electrode 104 and the positive electrode 105. In the secondary battery 100, a tab 107, which is a region where no active material is applied, is formed on each of the metal foil 104a of the negative electrode 104 and the metal foil 105a of the positive electrode 105. A plurality of tabs 107 collected on one end side in the stacking direction are connected to the terminal member 103 as a tab group. Further, the tab group includes a bent portion 108 that is bent or bent, and an extended portion 109 that extends from the bent portion 108 in the stacking direction of the electrode assembly 102 and is connected in contact with the terminal member 103.

  Further, the secondary battery of Patent Document 2 is provided with a bag-shaped insulating sheet covering the periphery of the electrode assembly between the case and the electrode assembly. As this insulating sheet, a film-like resin sheet is employed. In this secondary battery, the electrode assembly and the case are insulated by the insulating sheet.

JP 2002-298825 A JP2013-12428A

  By the way, in the secondary battery 100 of patent document 1, the tab group and the terminal member 103 are joined by welding. In such a secondary battery 100, the size of the joint area between the tab group and the terminal member 103 has a correlation with the current collection efficiency of the terminal member 103. In order to increase the current collection efficiency, It is desirable that the bonding area with the terminal member 103 is large.

  In order to increase the bonding area, it is conceivable to lengthen each tab and increase the area of a region where all the tabs overlap (overlapping region). However, if each tab is simply lengthened, the excess portion at the tip of each tab (the portion extending beyond the overlapping region) becomes long, so that this excess portion contacts the inner surface of the case or the electrode of a different pole of the electrode assembly. There is a fear. If the excess part of the tip of the tab comes into contact with the inner surface of the case or the electrode of a different electrode of the electrode assembly, the tab and the case or the electrode are short-circuited.

  In Patent Document 1, a configuration in which three electrode foils are simplified is illustrated, and this problem will be supplemented. In a secondary battery, it is not uncommon to stack 10 or more positive electrodes and negative electrodes, and in a large secondary battery, each electrode reaches several tens. Further, in order to increase the capacity of the secondary battery, the metal foil is set as thin as possible as compared with the thickness of the active material layer. Therefore, for example, when the same negative electrode is used and the tabs are gathered together at one end in the stacking direction as in Patent Document 1, the end of the tab on one end side and the end of the tab on the other end side are approximately the thickness of the electrode assembly. Deviation of only minutes occurs. On the other hand, since the tab (metal foil) is extremely thin, the internal and external deviations caused by bending after being gathered are relatively small. For this reason, assuming that the above-described overlapping region is set, the tab on one end side actually protrudes ahead of the overlapping region by a value close to the thickness of the electrode assembly.

  In addition, it becomes possible to insulate between the front-end | tip of a tab and a case by providing the insulating sheet of patent document 2 in such a secondary battery. However, even with such a secondary battery, it is not possible to suppress unnecessary contact of the surplus portion at the tip of the tab with the electrode assembly.

  The present invention has been made paying attention to the problems existing in the above-described prior art, and an object of the present invention is to provide a power storage device capable of suppressing unnecessary contact of the tips of the tab group with the electrode assembly. There is.

  Hereinafter, a power storage device for achieving the above-described objects includes an electrode assembly having a stacked structure in which a positive electrode and a negative electrode are stacked in a state of being insulated from each other, and a conductive member that is connected to the electrode assembly and transmits and receives electricity And a tab group in which one of the tab provided on the edge of the positive electrode and the tab provided on the edge of the negative electrode is collected, and a first bent portion having a shape bent in one direction, A tab group having an extending portion extending from the first bent portion in the stacking direction of the electrode assembly, and a joint portion provided in the extending portion and joined to the conductive member; and the conductive member And a case for housing the electrode assembly and the tab group, the power storage device having a gap sheet provided between the electrode assembly and the case, and the tab group The portion on the tip side of the joint is the case. A second bent portion bent in a direction approaching the electrode assembly in a manner extending toward the inner side of the tab, and the gap sheet is a portion on the tip side of the second bent portion of the tab group. And the electrode assembly.

  According to the power storage device, the excess portion at the tip of the tab group, that is, the portion extending beyond the region where the tabs of each positive electrode (or each negative electrode) are overlapped is bent into a shape toward the inward side of the case. It can suppress that an excessive part protrudes and contacts a case inner surface. Moreover, by extending at least a part of the gap sheet for adjusting the gap between the electrode assembly and the case, and sandwiching it between the electrode assembly and the portion on the tip side of the second bent portion of the tab group, By utilizing the gap sheet, it is possible to prevent the tip side portion of the tab group from unnecessarily contacting the electrode assembly.

In the above power storage device, it is preferable that the gap sheet is folded back between the electrode assembly and a portion of the tab group closer to the tip than the second bent portion.
According to the above power storage device, the gap sheet is sandwiched between the tab group and the electrode assembly in a double state, so that the gap sheet allows the electrode assembly at the front end side of the tab group to reach the electrode assembly. Unnecessary contact can be suitably suppressed.

  In the above power storage device, the gap sheet has a shape in which a portion of the second bent portion side covers the case side of the second bent portion, and extends between the second bent portion and the case. It is good to have.

According to the power storage device, the gap sheet can suitably insulate the tip side portion of the tab group from the case.
In the power storage device, it is preferable that the gap sheet has a protruding end in the stacking direction between the portion on the tip side of the tab group and the electrode assembly extending farther from the tip of the tab group.

  According to the power storage device, it is possible to cover the entire electrode assembly side in the portion on the tip side from the second bent portion of the tab group with the gap sheet. Unnecessary contact with the electrode assembly can be more suitably suppressed.

The power storage device preferably includes an insulating sheet provided between the electrode assembly and the case so as to cover the periphery of the electrode assembly and the gap sheet.
The power storage device has a structure in which an excessive portion at the tip end of the tab group easily moves relative to the electrode assembly. Therefore, the tips of the tab group may vibrate and the tips may move around the second bent portion. However, the insulation in the moving direction of the front end of the tab group is maintained by the insulating sheet disposed on the case inner wall side together with the gap sheet disposed on the electrode assembly side.

In the above power storage device, the gap sheet may be formed of a material harder than the insulating sheet.
According to the power storage device, since the gap sheet that requires high strength can be formed of a hard material, the strength of the gap sheet can be appropriately increased. In production, the insulating sheet needs to be formed of a relatively soft material, and it is difficult to increase the strength. However, by increasing the strength of the gap sheet closer to the tab group, it is easy to ensure insulation.

  A secondary battery can be used as the power storage device.

  According to this invention, it can suppress that the front-end | tip of a tab group contacts an electrode assembly unnecessarily.

The disassembled perspective view which shows the secondary battery of one Embodiment. The perspective view which shows the external appearance of a secondary battery. The fragmentary sectional view of a secondary battery. The disassembled perspective view which shows the component of an electrode assembly. Explanatory drawing explaining the tab group to which the electrically-conductive member was connected. Sectional drawing which expands and shows sectional structure of a tab group and its periphery. Sectional drawing along line 7-7 in FIG. 6 of the secondary battery. A side view showing a gap sheet. Sectional drawing which expands and shows the cross-sectional structure of the tab group of the secondary battery of a modification, and its periphery. The side view which shows the gap | interval sheet | seat of the secondary battery of a modification. Sectional drawing which expands and shows the cross-sectional structure of the tab group of the secondary battery of a modification, and its periphery. The side view which shows the gap | interval sheet | seat of the secondary battery of a modification. The side view which shows the gap | interval sheet | seat of the secondary battery of a modification. Sectional drawing which shows the connection aspect of the conventional tab group and an electrically-conductive member.

Hereinafter, an embodiment of a power storage device will be described with reference to FIGS.
As shown in FIG. 1 or 2, an electrode assembly 5 is accommodated in a case 3 in a secondary battery 2 as a power storage device. The case 3 includes a rectangular box-shaped main body member 4 and a rectangular flat plate-shaped lid member 6 that closes the opening 4 a of the main body member 4. Both the main body member 4 and the lid member 6 are made of metal (for example, stainless steel or aluminum). The secondary battery 2 of the present embodiment is a square battery whose outer shell forms a square shape, and is a lithium ion battery.

  The electrode assembly 5 is electrically connected to electrode terminals including a positive electrode terminal 7 and a negative electrode terminal 8 that transmit and receive electricity to and from the electrode assembly 5. The positive electrode terminal 7 and the negative electrode terminal 8 are exposed to the outside of the case 3 through a pair of opening holes 6 a arranged in parallel with the lid member 6 at a predetermined interval. Between each electrode terminal and the opening 6a of the cover member 6, the ring-shaped insulating member 9a for insulating between an electrode terminal and the cover member 6 is each attached.

  The secondary battery 2 includes a positive electrode conductive member 23 that electrically connects the positive electrode terminal 7 and the electrode assembly 5, and a negative electrode conductive member 24 that electrically connects the negative electrode terminal 8 and the electrode assembly 5. . The positive electrode conductive member 23 and the negative electrode conductive member 24 have a rectangular flat plate shape. The lengths of the positive electrode conductive member 23 and the negative electrode conductive member 24 along the short direction are shorter than the length along the stacking direction L of the electrode assembly 5. Further, the length along the longitudinal direction of the positive electrode conductive member 23 and the negative electrode conductive member 24 is a length that does not interfere with each other and does not interfere with the inner surface 4 b of the main body member 4.

  As shown in FIG. 1 or FIG. 3, an insulating cover for insulating the positive electrode conductive member 23 and the negative electrode conductive member 24 from the lid member 6 between the positive electrode conductive member 23 and the negative electrode conductive member 24 and the lid member 6. 16 is attached. The insulating cover 16 has a U-shaped cross section including a rectangular flat plate-like base portion 16a and side wall portions 16b projecting from both lateral ends of the base portion 16a toward the electrode assembly 5 side. . The insulating cover 16 is sandwiched between the lid member 6 and the positive electrode conductive member 23 and the negative electrode conductive member 24.

  An insulating sheet 9b for insulating the main body member 4 from the electrode assembly 5 accommodated therein is disposed between the inner surface 4b of the main body member 4 constituting the case 3 and the electrode assembly 5. Yes. The insulating sheet 9b is made of an electrically insulating resin material (for example, PP) and is not illustrated, but is formed in a bag shape so as to cover the electrode assembly 5 by bending a single soft resin sheet. Yes. The insulating sheet 9 b has a shape that covers almost the entire inner surface 4 b of the main body member 4 of the case 3.

  As shown in FIG. 4, the electrode assembly 5 includes a sheet-like positive electrode 10 and a sheet-like negative electrode 11. The positive electrode 10 has a positive electrode metal foil (aluminum foil in this embodiment) 13 and a positive electrode active material layer 14 formed by applying a positive electrode active material on both surfaces thereof. The negative electrode 11 has a negative electrode metal foil (copper foil in this embodiment) 17 and a negative electrode active material layer 18 formed by applying a negative electrode active material on both surfaces thereof. Specifically, the electrode assembly 5 has a layered structure in which a separator 12 is interposed between the positive electrode 10 and the negative electrode 11 to form a layered structure. The electrode assembly 5 is configured by laminating a plurality of positive electrodes 10 and a plurality of negative electrodes 11 as shown in FIG. 5, for example. That is, the electrode assembly 5 is provided with a plurality of sets each including the positive electrode active material layer 14, the negative electrode active material layer 18, and the separator 12.

  As shown in FIG. 4, the positive electrode 10 has a positive electrode uncoated portion composed of a region where the positive electrode active material is not applied to the positive metal foil 13. Specifically, a positive electrode tab 15 made of an uncoated positive electrode portion is provided on a part of the edge 10 a of the positive electrode 10 so as to protrude. The negative electrode 11 has a negative electrode uncoated portion composed of a region where the negative electrode active material is not applied to the negative electrode metal foil 17. And the negative electrode tab 19 which consists of a negative electrode uncoated part is provided in a part of edge 11a of the negative electrode 11 so that it may protrude. The positive electrode tab 15 and the negative electrode tab 19 are provided at positions where the positive electrode tab 15 and the negative electrode tab 19 do not overlap with each other in a state where the positive electrode 10 and the negative electrode 11 are laminated.

  The positive electrodes 10 constituting the electrode assembly 5 are stacked such that the respective positive electrode tabs 15 are arranged in a line along the stacking direction L. Similarly, the respective negative electrodes 11 constituting the electrode assembly 5 are stacked such that the respective negative electrode tabs 19 are arranged in a line along the stacking direction L.

  As shown in FIG. 1, the positive electrode tabs 15 are gathered in the range from one outermost layer to the other outermost layer in the stacking direction L of the electrode assembly 5 at the edge 5 a of the electrode assembly 5. A positive electrode tab group 21 is provided. Similarly, the negative electrode tabs 19 are also collected on the edge 5a of the electrode assembly 5 in a range from one outermost layer to the other outermost layer in the stacking direction L in the electrode assembly 5 to be the negative electrode tab group 22. Is provided. The positive electrode conductive member 23 is bonded to the positive electrode tab group 21, and the negative electrode conductive member 24 is bonded to the negative electrode tab group 22.

  Next, the manufacturing process and bonding structure of the positive electrode tab group 21 and the positive electrode conductive member 23 and the manufacturing process and bonding structure of the negative electrode tab group 22 and the negative electrode conductive member 24 will be described in detail with reference to FIGS. 5 and FIG. 6 illustrate the bonding structure of the positive electrode tab group 21 and the positive electrode conductive member 23. This bonding structure is the same as the bonding structure of the negative electrode tab group 22 and the negative electrode conductive member 24. It is. For this reason, below, the joining structure of the positive electrode tab group 21 and the positive electrode conductive member 23 is demonstrated. In the following description, if the positive electrode tab 15 is read as the negative electrode tab 19, the positive electrode tab group 21 is read as the negative electrode tab group 22, and the positive electrode conductive member 23 is read as the negative electrode conductive member 24, the negative electrode tab group 22 and the negative electrode conductive member 24 are read. This is an explanation of the joint structure.

  As shown in FIG. 5, first, in the stacking direction L of the electrode assembly 5, one outermost positive electrode tab 15 (labeled “H1” in FIG. 5) and the other outermost positive electrode tab 15 (see FIG. 5). 5 are labeled as “H2”). At this time, the positive electrode conductive member 23 is in contact with the positive electrode tab 15 (H1). As a result, the positive electrode tabs 15 that were independent at the stacking stage are collected on the positive electrode tab 15 (H1) side to form the positive electrode tab group 21. The positive electrode tab group 21 is joined by resistance welding while being sandwiched between the positive electrode conductive member 23 and the auxiliary plate 26. Thereby, the positive electrode tab group 21 of the electrode assembly 5 and the positive electrode conductive member 23 are electrically connected. The auxiliary plate 26 is a metal plate made of the same metal material as the positive electrode metal foil 13. Resistance welding is a method in which the objects to be joined (positive tab group 21, positive electrode conductive member 23, and auxiliary plate 26 in FIG. 5) are sandwiched between a pair of welding electrodes and welded.

  In this embodiment, each positive electrode tab 15 is formed in the same shape. Therefore, when the positive electrode tabs 15 are aggregated as the positive electrode tab group 21, the closer the positive electrode tab 15 to the positive electrode tab 15 (H 1) in the stacking direction L of the electrode assembly 5, the closer to the tip portion of the positive electrode tab 15. Length increases. In the present embodiment, the joint portion W for joining the positive electrode tabs 15 is set in a region where all the positive electrode tabs 15 are superposed. The positive electrode tab group 21 and the positive electrode conductive member 23 are bonded at the bonding portion W, and the positive electrode tab group 21 and the positive electrode conductive member 23 are electrically connected.

  As shown in FIG. 6, the positive electrode tab group 21 includes a first bent portion 27 that curves in one direction (clockwise direction in FIG. 6), and the stacking direction L of the electrode assembly 5 from the first bent portion 27. And an extending portion 28 extending in the right direction in FIG. A part of the extending portion 28 is a joint portion W. The structure of the positive electrode tab group 21 is such that the positive electrode tabs 15 are aggregated as the positive electrode tab group 21 and joined to the positive electrode conductive member 23, and then the positive electrode tab group 21 and the positive electrode conductive member 23 are stacked in the stacking direction L of the electrode assembly 5. This is realized by turning it so as to be tilted (rightward in FIG. 6). The positive electrode conductive member 23 is bonded to the surface of the extending portion 28 of the positive electrode tab group 21 that is away from the electrode assembly 5 (upward in FIG. 6).

  In the secondary battery 2 of the present embodiment, the extension portion 28 is long in order to increase the area of the joint portion W between the positive electrode tab group 21 and the positive electrode conductive member 23, and the positive electrode tab group 21 is bent in the first bending direction. If the structure is bent only at the portion 27, the tip of the positive electrode tab group 21 may come into contact with the inner surface 4b of the case 3 or a different electrode (specifically, the negative electrode 11) of the electrode assembly 5.

  Therefore, in the present embodiment, the positive electrode tab group 21 is bent in such a manner that a portion on the front end side of the joint portion W of the extension portion 28 extends toward the inside of the case 3 (left side in FIG. 6). The second bent portion 29 is provided. In the second bent portion 29, the tip end of the positive electrode tab group 21 is bent in the same bending direction as that of the first bent portion 27, that is, the portion on the front end side of the positive electrode tab group 21 approaches the electrode assembly 5. The structure is folded in the bending direction (clockwise direction in FIG. 6). In the secondary battery 2 of the present embodiment, the positive electrode conductive member 23, the first bent portion 27, and the second bent portion 29 are sandwiched between the pair of side wall portions 16 b of the insulating cover 16. ing.

  As shown in FIG. 6 or FIG. 7, the secondary battery 2 includes one end face (right side in FIG. 6) of the electrode assembly 5 in the stacking direction L and the body member 4 of the case 3 (specifically, the insulating sheet 9b). ) And a gap sheet 31 provided therebetween. The gap sheet 31 is formed of a resin material having electrical insulation (for example, PP). The gap sheet 31 is arranged to reduce the gap in the stacking direction L between the electrode assembly 5 and the case 3. In the present embodiment, at least one gap sheet 31 is arranged, and the number of gap sheets 31 (5 sheets in the example shown in FIG. 6) is set such that the gap is substantially “0”. Adjusted.

  As shown by a broken line in FIG. 8, the gap sheet 31 is basically formed in a rectangular flat plate shape, and more specifically, the shape is the main body portion of each electrode excluding the tab, that is, the active material layer. And the same shape. Further, as shown by a solid line in FIG. 8, among the plurality of gap sheets 31, the sheet is disposed at a position closest to the inner surface of the case 3, that is, a position farthest from the electrode assembly 5 (specific sheet 32). The base plate 32a has the same rectangular flat plate shape as the other gap sheet 31, and two protruding portions 32b that protrude in a rectangular flat plate shape on one side of the base portion 32a. The specific sheet 32 has a groove 32c at the boundary between the base portion 32a and the protruding portion 32b.

  As shown in FIG. 6 or FIG. 7, in the secondary battery 2 of the present embodiment, the groove 32 c of the specific sheet 32 (specifically, the specific sheet 32) has a groove 32 c so that each protrusion 32 b of the specific sheet 32 falls to the electrode assembly 5 side. It arrange | positions in the state bent in the formation site | part. As a result, one of the projecting portions 32b extends to a position sandwiched between the electrode assembly 5 and the portion on the tip end side of the second bent portion 29 of the positive electrode tab group 21, and the other is the negative tab group 22. It extends to a position that is sandwiched between the electrode assembly 5 and a portion on the tip side of the second bent portion 29. Further, when the protruding portion 32b is bent, if the position of the gap sheet 31 other than the specific sheet 32 is shifted to the second bent portion 29 side, the gap sheet 31 is pressed by the bent protruding portion 32b. As a result, it moves in a direction away from the second bending portion 29, and the arrangement position of the gap sheet 31 is corrected. The gap sheet 31 (specifically, the specific sheet 32) is fixed to the electrode assembly 5 with an adhesive tape 33 on four sides thereof.

  In addition, one of the protruding portions 32 b of the specific sheet 32 has a protruding end in the stacking direction L behind the second bent portion 29 of the positive electrode tab group 21 and is deeper than the front end of the positive electrode tab group 21. It extends to the position (left side in FIG. 7). The other protruding portion 32 b of the specific sheet 32 has a protruding end in the stacking direction L behind the positive electrode tab group 21 along the tip side of the second bent portion 29 of the negative electrode tab group 22. Extends to position.

  As shown in FIG. 3 or FIG. 7, in the secondary battery 2, almost the entire inner surface of the body member 4 of the case 3 is covered with the insulating sheet 9 b, so that the electrode assembly 5, the positive electrode is covered with the insulating sheet 9 b. The periphery of the tab group 21 and the negative electrode tab group 22 is covered. Accordingly, the insulating sheet 9b allows the first bent portion 29 between the second bent portion 29 of the positive electrode tab group 21 (or the negative electrode tab group 22) and the case 3, or the first bent portion of the positive electrode tab group 21 (or the negative electrode tab group 22). 27 is insulated from case 3.

According to the secondary battery 2 of the present embodiment, the following effects can be obtained.
(1) In the secondary battery 2, the excess portion at the tip of the positive electrode tab group 21 (or the negative electrode tab group 22), that is, the portion extending beyond the joint portion W of each positive electrode tab 15 (or each negative electrode tab 19) is the case 3. It can suppress that the surplus part protrudes and contacts the inner surface of case 3 by bending in the aspect extended toward inward. Therefore, the positive electrode tab group 21 and the case 3 and the negative electrode tab group 22 and the case 3 can be easily insulated. In addition, in the secondary battery 2, the gap between the protruding portion 32 b of the gap sheet 31 (specifically, the specific sheet 32) and the portion between the electrode assembly 5 and the portion on the tip side of the second bent portion 29 of the positive electrode tab group 21 are separated. And the other side of the negative electrode tab group 22 from the second bent portion 29 and the electrode assembly 5 are blocked. Therefore, using the gap sheet 31, the tip side portion of the positive electrode tab group 21 makes unnecessary contact with the electrode assembly 5, and the tip side portion of the negative electrode tab group 22 makes unnecessary contact with the electrode assembly 5. Can be suppressed.

  (2) Since the protruding end of one protruding portion 32b in the stacking direction L extends deeper than the tip of the positive electrode tab group 21, the electrode in the portion on the front end side of the second bent portion 29 of the positive electrode tab group 21 The entire assembly 5 side can be covered with the protrusion 32b. In addition, since the protruding end in the stacking direction L of the other protruding portion 32 b extends farther from the tip of the negative electrode tab group 22, the electrode set in the portion on the tip side of the second bent portion 29 of the negative electrode tab group 22. The whole of the solid 5 side can be covered with the protrusion 32b. Therefore, the protrusion 32 b of the specific sheet 32 can favorably suppress unnecessary contact of the tip side portion of the positive electrode tab group 21 and the tip side portion of the negative electrode tab group 22 with the electrode assembly 5.

  (3) The secondary battery 2 has a structure in which a surplus portion at the tip of the positive electrode tab group 21 (or the negative electrode tab group 22) easily moves relative to the electrode assembly 5. For this reason, the tip of the positive electrode tab group 21 (or the negative electrode tab group 22) may vibrate, and the tip may move around the second bent portion 29 as an axis. In this regard, in the secondary battery 2, the positive electrode tab group 21 (or the negative electrode tab group 22) is formed by the insulating sheet 9b disposed on the inner wall side of the case 3 together with the gap sheet 31 disposed on the electrode assembly 5 side. Insulation in the moving direction of the tip can be maintained.

  (4) After the positive electrode conductive member 23 is joined to the positive electrode tab group 21, the excess portion of the positive electrode tab group 21 is cut, or after the negative electrode conductive member 24 is joined to the negative electrode tab group 22, the excess portion of the negative electrode tab group 22 If these are cut, it is possible to avoid unnecessary contact of these surplus portions with the electrode assembly 5. However, in this case, there is a possibility that a small piece of a tab generated at the time of cutting the surplus portion may enter the inside of the case 3. In the present embodiment, without performing the operation of cutting the surplus portions of the positive electrode tab group 21 and the negative electrode tab group 22, the electrode sets on the front end side portion of the positive electrode tab group 21 and the front end side portion of the negative electrode tab group 22. Unnecessary contact with the solid 5 can be suppressed.

  (5) Instead of extending the entire one side of the base portion 32a of the specific sheet 32, but having the protruding portion 32b having a shape in which one side of the base portion 32a is partially extended, the side where the protruding portion 32b is formed However, it is possible to easily fix the specific sheet 32 to the electrode assembly 5 with the adhesive tape 33 at a portion where the protruding portion 32b is not formed. Therefore, the specific sheet 32 can be suitably fixed to the electrode assembly 5.

In addition, the said embodiment can also be implemented with the following forms which changed this suitably.
O The gap sheet 31 may be made of a material harder than the insulating sheet 9b. According to such a secondary battery, since the gap sheet 31 requiring high strength can be formed of a hard material (for example, PPS), the strength of the gap sheet 31 can be appropriately increased. it can. In the production of the secondary battery, the insulating sheet 9b is bent and formed into a bag shape. Therefore, it is necessary to form the insulating sheet 9b with a relatively soft material, and it is difficult to increase its strength. In this respect, according to the secondary battery, the strength of the gap sheet 31 closer to the tab groups 21 and 22 can be increased, so that it is easy to ensure insulation.

  In such a secondary battery, only the specific sheet 32 of the plurality of gap sheets 31 is formed of a material harder than the insulating sheet 9b, and the other gap sheets 31 are formed of a relatively soft material. May be. According to such a secondary battery, when the hard material constituting the specific sheet 32 is more expensive than the relatively soft material constituting the insulating sheet 9b, the gap sheet 31 formed of such a hard material. The secondary battery can be manufactured at low cost.

  As shown in FIG. 9, the protruding portion 42 b of the specific sheet 42 is positioned between the electrode assembly 5 and the portion on the tip end side of the second bent portion 29 of the positive electrode tab group 21 (or the negative electrode tab group 22). It may be a folded shape. The protruding portion 42b of the specific sheet 42 extends inwardly of the case 3 along the portion on the tip side of the second bent portion 29 of the positive electrode tab group 21 (or the negative electrode tab group 22) starting from the base portion 32a (see FIG. 9 and a portion extending toward the vicinity of the inner surface of the case 3 by being folded back at an acute angle at the protruding end of the portion. According to such a secondary battery, the protruding portion 42b of the specific sheet 42 is sandwiched between the tip side portion of the positive electrode tab group 21 (or the negative electrode tab group 22) and the electrode assembly 5 in a doubled state. As a result, it is possible to suitably prevent the positive electrode tab group 21 (or the negative electrode tab group 22) from making unnecessary contact with the electrode assembly 5 by the protruding portion 42b.

  Further, as shown in FIG. 10, a groove 42c may be formed in a portion where the protruding portion 42b of the specific sheet 42 is folded. As a result, when the specific sheet 42 is disposed, a desired portion can be accurately folded back, which facilitates the disposition.

The specific sheet is not limited to be disposed in a state where the protruding portion 42b is bent so as to form an acute angle, but may be disposed in a state where the protruding portion is bent so as to be bent.
As shown in FIG. 11, the protrusion 52 b of the specific sheet 52 is folded between the electrode assembly 5 and the portion on the tip side of the second bent portion 29 of the positive electrode tab group 21 (or the negative electrode tab group 22). The shape may be changed. Then, the tip side portion of the protrusion 52b of the specific sheet 52 is shaped to extend between the second bent portion 29 and the case 3 so as to cover the case 3 side of the second bent portion 29. May be. In the example shown in FIG. 11, the specific sheet 52 has a shape in which a portion on the front end side of the protruding portion 52 b extends along the inner surface of the case 3, and the same portion corresponds to the side wall portion 16 b of the insulating cover 16 and the case 3. Is sandwiched between the insulating cover 16). According to such a secondary battery, in addition to suppressing unnecessary contact between the tip side portion of the positive electrode tab group 21 (or the negative electrode tab group 22) and the electrode assembly 5 by the protruding portion 52b of the specific sheet 52, the positive electrode The portion of the tab group 21 (or the negative electrode tab group 22) on the tip side and the case 3 can be insulated.

  Further, in such a secondary battery, as shown in FIG. 12, each of the specific sheet 52 has a protruding portion 52b and a portion where the leading end of the protruding portion 52b is bent in a direction along the inner surface of the case 3. The groove 52c may be formed. As a result, when the specific sheet 52 is disposed, a desired portion can be accurately bent, so that the disposition is facilitated.

  In the secondary battery, a portion of the protruding portion 52b of the specific sheet 52 that is sandwiched between the side wall portion 16b of the insulating cover 16 and the case 3 may be joined to the side wall portion 16b. According to such a secondary battery, unnecessary vibration of the protrusion 52b of the specific sheet 52 and displacement of the arrangement position can be suppressed, and the protrusion 52b can prevent the positive electrode tab group 21 (or the negative electrode tab group 22) from leading. And the electrode assembly 5, or the portion on the tip side of the positive electrode tab group 21 (or the negative electrode tab group 22) and the case 3 can be properly shielded.

  The protrusion in the stacking direction L between the tip side portion of the positive electrode tab group 21 (or the negative electrode tab group 22) of the specific sheets 32, 42, 52 and the electrode assembly 5 is the positive electrode tab group 21 (or The negative electrode tab group 22) may not extend to the back from the tip. Even in such a secondary battery, unnecessary contact between the electrode assembly 5 and the portion on the tip side of the second bent portion of the positive electrode tab group 21 (or the negative electrode tab group 22) can be suppressed.

  In the above embodiment, only a part of one side (protruding part 32b) of the base part 32a of the specific sheet 32 is protruded. Instead, as shown in FIG. 13, the entire side of the specific sheet 62 may be extended.

  The bending direction of the first bending portion 27 may be different between the positive electrode tab group 21 and the negative electrode tab group 22. In such a secondary battery, a gap sheet may be attached to both end faces in the stacking direction L of the electrode assembly 5. Then, the gap sheet attached to one end face was extended to a position sandwiched between the electrode assembly 5 and the portion on the tip side from the second bent portion 29 of the positive electrode tab group 21, and attached to the other end face. What is necessary is just to extend a gap | interval sheet | seat to the position pinched | interposed between the part on the front end side from the 2nd bending part 29 of the negative electrode tab group 22, and the electrode assembly 5. FIG.

  (Circle) the position which gathers the positive electrode tab 15 and the negative electrode tab 19 can be made into arbitrary positions. Such a position is preferably a position within a range from one outermost layer in the stacking direction L of the electrode assembly 5 to the other outermost layer.

The first bent portion 27 may be formed by bending the positive electrode tab group 21 or the negative electrode tab group 22.
○ A structure in which the second bent portion 29 is formed and the specific sheet is extended between the electrode assembly 5 and a portion closer to the tip than the second bent portion 29 is formed of the positive electrode tab group 21 and the negative electrode tab group 22. You may make it apply only to one side.

  The secondary battery 2 of the above embodiment is also applied to a secondary battery in which one of a plurality of types of gap sheets having different thicknesses is selected and disposed, with the configuration appropriately changed. Can do. In such a secondary battery, the gap sheet is formed in a shape that extends to a position sandwiched between the electrode assembly 5 and the portion on the tip side of the second bent portion 29 of the positive electrode tab group 21 (or the negative electrode tab group 22). That's fine.

The conductive members 23 and 24 have rectangular plate shapes, but may have other shapes such as a cylindrical shape (bar shape) or a rectangular parallelepiped shape.
The conductive members 23 and 24 may be integrated with the electrode terminals. In the above embodiment, by connecting the tab groups 21 and 22 via the plate-like conductive members 23 and 24, the joining with the tab groups 21 and 22 by resistance welding (for example, spot welding) becomes easy, and the electrodes By overlapping the terminals and the tab groups 21 and 22 in the vertical direction (tab side direction), an increase in the dead space in the tab side direction of the electrode assembly 5 can also be suppressed.

The joining of the tab groups 21 and 22 and the conductive members 23 and 24 can be performed by methods other than resistance welding such as ultrasonic welding and soldering.
○ The tabs 15 and 19 are not limited to those formed integrally with the metal foil forming the electrodes 10 and 11, but a rectangular metal foil piece formed separately is formed as an active material layer. It may be added later. For example, after forming an active material layer on each metal foil for a so-called wound electrode assembly, in which a long strip of positive electrode metal and a negative electrode of the same shape are stacked via a separator and then wound. The present invention can also be applied to a structure in which tabs made of rectangular metal pieces are joined to each metal foil so that the tabs overlap at predetermined positions.

  The present invention is not limited to the laminated secondary battery 2 as in the above embodiment, and may be applied to a wound secondary battery in which a belt-like positive electrode and a negative electrode are wound to form a layered laminated structure. In the wound secondary battery, the positive electrode and the negative electrode are insulated with a separator interposed therebetween. And when applying to a winding type secondary battery, the positive electrode tab 15, the positive electrode tab group 21, the negative electrode tab 19, and the negative electrode tab group 22 like embodiment should just be formed.

(Circle) the vehicle carrying the secondary battery 2 of embodiment may be a motor vehicle, and an industrial vehicle may be sufficient as it.
The secondary battery 2 is a lithium ion secondary battery, but is not limited thereto, and may be another secondary battery. In short, any ion may be used as long as ions move between the positive electrode active material layer and the negative electrode active material layer and transfer charge.

  The present invention may be embodied in a power storage device such as an electric double layer capacitor.

  2 ... secondary battery, 3 ... case, 4 ... body member, 4b ... inner surface, 5 ... electrode assembly, 5a, 10a, 11a ... edge, 6 ... lid member, 9b ... insulating sheet, 10 ... positive electrode, 11 DESCRIPTION OF SYMBOLS ... Negative electrode, 12 ... Separator, 13 ... Positive electrode metal foil, 14 ... Positive electrode active material layer, 15 ... Positive electrode tab, 16 ... Insulation cover, 17 ... Negative electrode metal foil, 18 ... Negative electrode active material layer, 19 ... Negative electrode tab, 21 ... positive electrode tab group, 22 ... negative electrode tab group, 23 ... positive electrode conductive member, 24 ... negative electrode conductive member, 27 ... first bent portion, 28 ... extending portion, 29 ... second bent portion, 31 ... gap sheet, 32, 42, 52, 62 ... specific sheet, 32b, 42b, 52b ... projection, W ... joint.

Claims (7)

An electrode assembly having a laminated structure in which a positive electrode and a negative electrode are laminated in a state in which they are insulated;
A conductive member connected to the electrode assembly for transferring electricity;
A tab group in which one of a tab provided on an edge of the positive electrode and a tab provided on an edge of the negative electrode is collected, and a first bent portion having a shape bent in one direction; A tab group having an extending portion extending in the stacking direction of the electrode assembly from one bent portion, and a joining portion provided in the extending portion and joined to the conductive member;
A case for housing the conductive member, the electrode assembly, and the tab group;
A power storage device comprising:
The power storage device has a gap sheet provided between the electrode assembly and the case,
The tab group has a second bent portion bent in a direction approaching the electrode assembly in a manner in which a portion on the tip side of the joint extends toward the inside of the case,
The power storage device, wherein the gap sheet extends to a position sandwiched between a portion of the tab group on the tip side from the second bent portion and the electrode assembly.   2. The power storage device according to claim 1, wherein the gap sheet is folded between a portion of the tab group closer to the tip than the second bent portion and the electrode assembly.   The gap sheet has a shape in which a portion of the second bent portion side covers the case side of the second bent portion, and extends between the second bent portion and the case. The power storage device according to claim 2.   The gap sheet has a protruding end in the stacking direction between a portion on the tip side of the tab group and the electrode assembly extending from the tip of the tab group to the back. The power storage device according to claim 3.   The power storage device according to any one of claims 1 to 4, further comprising an insulating sheet provided between the electrode assembly and the case in a shape covering the periphery of the electrode assembly and the gap sheet.   The power storage device according to claim 5, wherein the gap sheet is made of a material harder than the insulating sheet.   The power storage device according to claim 1, wherein the power storage device is a secondary battery.