JP6064879B2 - Power storage device - Google Patents

Description

  The present invention relates to a power storage device having 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. 12, 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. The tab group also 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 contacts and is connected to 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, an excessive portion (a portion extending beyond the overlapping region) at the tip of the tab becomes long, so that there is a possibility that the excessive portion contacts the inner surface of the case. If the surplus portion at the tip of the tab contacts the inner surface of the case, the tab and the case 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, in such a secondary battery, each tab made of metal foil is in contact with an insulating sheet made of a film-like resin material. On the other hand, in Patent Document 2, the insulating sheet is bent and used so that the front and back of the electrode assembly can be covered with a single sheet. Insulating sheets that cover even the side edges and bottom of the electrode assembly by bending more complicatedly have been proposed in the past. However, such insulating sheets do not have any trouble in bending and use. It is set to be relatively soft. Therefore, when the tip of the tab is pressed against the insulating sheet due to vibration of the secondary battery, the insulating sheet may be damaged, and in this case, the tab and the case may be short-circuited.

  The present invention has been made paying attention to the problems existing in the above-described prior art, and an object thereof is to provide a power storage device capable of suitably insulating between a tab and a case.

  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 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 bent portion bent in one direction, and the bent portion A tab group having an extending portion extending in the stacking direction of the electrode assembly from the above, a joint group provided in the extending portion and joined to the conductive member, the conductive member, the electrode assembly, A case accommodating the tab group; and an insulating sheet provided between the electrode assembly and the case in a shape covering the periphery of the electrode assembly. And the said electrical storage apparatus has a gap | interval sheet | seat provided between the said electrode assembly and the said insulation sheet | seat, and the said gap | interval sheet | seat is a tab so that the part of the front end side rather than the said junction part of the said tab group may be covered. Extending on the same side.

  According to the power storage device, by extending a part of the gap sheet for adjusting the gap between the electrode assembly and the case and covering the tip of the tab group, the tab group and the case Can be suitably insulated.

The said electrical storage apparatus WHEREIN: The said insulating sheet is good to extend to the position which covers the circumference | surroundings of the said tab group.
According to the power storage device, the tab group and the case can be insulated not only by the gap sheet but also by the insulating sheet. Therefore, it is possible to more suitably insulate between the tab group and the case.

In the above power storage device, the gap sheet may be formed of a material harder than the insulating sheet.
Usually, the power storage device has a structure in which the electrode assembly does not move relative to the case. Therefore, the possibility that a large force is applied to the insulating sheet that insulates between the electrode assembly and the case is low, and the strength required for the insulating sheet is low. On the other hand, the excessive portion at the tip of the tab group has a structure that easily moves relative to the case. For this reason, when the tip of the tab group vibrates and moves relatively, a large force may be applied to the portion where the gap sheet used for insulation between the tab group and the case is in contact with the tab group. Yes, the strength required for the gap sheet is high.

  In addition, while forming an insulating sheet with a hard material and making it the shape extended to the position which covers the said case side of a tab group, the tab group and a case are suppressed, suppressing the fall of the reliability of an insulating sheet. It becomes possible to insulate them. However, in this case, since the entire portion covering the periphery of the electrode assembly has high strength, even a portion having a low required strength is covered with a high strength sheet.

  In this regard, according to the above power storage device, the portion covering the case side of the tab group, that is, the portion requiring high strength can be configured by the gap sheet made of a hard material, so that the strength of the portion is appropriately increased. Can be high. And since an insulating sheet is formed with a comparatively soft material, it can also suppress that the part with the low intensity | strength requested | required becomes high intensity | strength excessively. Thus, according to the power storage device, the gap sheet and the insulating sheet can have appropriate strengths required for each.

  In the above power storage device, if the insulating sheet is provided on the conductive member and insulates the conductive member and the case, the gap sheet has its tip joined to the insulating cover. Good.

According to the power storage device, vibration of the gap sheet and displacement of the arrangement position can be suppressed, and the tab group and the case can be suitably insulated by the gap sheet.
In the power storage device, a plurality of the gap sheets are provided so as to overlap in the stacking direction, and only the one that is disposed closest to the inner surface side of the case extends between the tab group and the case. Good.

  According to the above power storage device, the gap between the gap sheet and the case is made smaller compared to the case where the inner sheet of the plurality of gap sheets extends between the tab group and the case. Therefore, it is possible to suppress a decrease in the content of the case.

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

  According to the present invention, it is possible to suitably insulate between the tab group and the case.

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. 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. 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 although not shown in the drawing, a single soft resin sheet is bent and formed into a bag shape so as to cover the electrode assembly 5. Has been.

  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 4 b of the case 3.

  Therefore, in the present embodiment, the positive electrode tab group 21 has a second shape in which a portion on the tip side of the joint portion W of the extension portion 28 is bent toward the inner side of the case 3 (left side in FIG. 6). The bent portion 29 is provided. The second bent portion 29 has a structure in which the tip of the positive electrode tab group 21 is folded back in the same bending direction as the first bent portion 27 (clockwise direction in FIG. 6).

  Further, in the secondary battery 2 of the present embodiment, the insulating cover 16 is disposed between the side wall portion 16b and the positive electrode conductive member 23 in accordance with the formation of the first bent portion 27 and the second bent portion 29. It is attached to the positive electrode conductive member 23 with the first bent portion 27 and the second bent portion 29 sandwiched therebetween.

  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 is arranged, and the number of gap sheets 31 (5 sheets in the example shown in FIG. 6) is adjusted so that the gap is substantially “0”. Is done. The gap sheet 31 is basically formed in a rectangular flat plate shape. More specifically, the gap sheet 31 has the same shape as the main body portion of each electrode excluding the tab, that is, the active material layer. The four sides are fixed to the electrode assembly 5 by the adhesive tape 33.

  In the present embodiment, among the plurality of gap sheets 31, the one disposed on the innermost side of the case 3, that is, the position farthest from the electrode assembly 5 (specific sheet 32) is the second bending sheet. The portion 29 covers the case 3 side and extends between the positive electrode tab group 21 and the case 3 (insulating sheet) and between the negative electrode tab group 22 and the case 3.

  As indicated by broken lines in FIG. 8, the sheets other than the specific sheet 32 among the plurality of gap sheets 31 are formed in a rectangular flat plate shape. In addition, as indicated by a solid line in FIG. 8, the specific sheet 32 among the plurality of gap sheets 31 has a rectangular flat base portion 32a that is the same as the other gap sheets 31, and a rectangular shape on one side of the base portion 32a. It has two protrusions 32b protruding in a flat plate shape.

  Then, as shown in FIG. 6 or FIG. 7, one of the two protrusions 32 b passes between the positive electrode tab group 21 and the case 3 and reaches between the side wall 16 b of the insulating cover 16 and the inner surface of the case 3. While being arranged in an extending manner, the other is arranged in such a manner that it passes between the negative electrode tab group 22 and the case 3 and extends between the side wall portion 16 b of the insulating cover 16 and the inner surface of the case 3.

  As shown in FIG. 3 or FIG. 7, the insulating sheet 9 b has a shape that covers almost the entire inner surface of the main body member 4 of the case 3. Therefore, in the secondary battery 2, the periphery of the electrode assembly 5, the positive electrode tab group 21, and the negative electrode tab group 22 is covered with the insulating sheet 9b.

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 is bent to the shape facing inward. Even if the end of the bent tab returns to its original state due to elasticity, in the secondary battery 2, the positive electrode tab group is formed by one of the protrusions 32 b of the gap sheet 31 (specifically, the specific sheet 32). The second bent portion 29 of 21 and the inner surface of the case 3 are blocked, and the second bent portion 29 of the negative electrode tab group 22 and the inner surface of the case 3 are blocked by the other. Therefore, it is possible to suitably insulate between the positive electrode tab group 21 and the case 3 and between the negative electrode tab group 22 and the case 3 using the gap sheet 31.

  (2) Since the insulating sheet 9b extends to a position covering the periphery of the positive electrode tab group 21 and the negative electrode tab group 22, between the positive electrode tab group 21 and the case 3 or between the negative electrode tab group 22 and the case 3, In addition to being insulated by the protrusion 32b of the gap sheet 31, it can also be insulated by the insulating sheet 9b. Therefore, it is possible to more suitably insulate between the positive electrode tab group 21 and the case 3 and between the negative electrode tab group 22 and the case 3.

  (3) The insulating sheet 9b is bent to cover the electrode assembly 5, and is formed into a bag shape. For this reason, it is necessary to set the thickness and material so as to obtain a soft sheet that can be processed, and it is difficult to increase the strength. On the other hand, since the gap sheet 31 is arranged so as to be laminated with the electrode assembly 5 in order to adjust the gap between the electrode assembly 5 and the case 3, it is not necessary to bend the gap sheet 31. For this reason, it is easy to use a hard and strong sheet.

  (4) Of the plurality of gap sheets 31, only the one disposed on the inner surface side of the case 3 (specific sheet 32) has the protruding portion 32b, so the main body of the lid member 6 in the case 3 Assembly to the member 4 is facilitated. Since the gap sheet 31 is used to fill a gap with the case 3 due to a manufacturing error of the electrode assembly 5, the number of the sheets varies depending on the cell. If the upper end of the gap sheet 31 is all extended and disposed between the insulating cover 16 and the inner surface of the case 3, the thickness including the insulating cover 16 changes every time, and it may be difficult to assemble the main body member 4. In the above embodiment, since only the specific sheet 32 has the protruding portion 32b, the thickness including the insulating cover 16 is determined, and it is possible to avoid the case 3 that is difficult to assemble.

  (5) 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. Insulated by bending to the inward shape. If the positive electrode tab member 21 is joined to the positive electrode tab group 21 and then the excess portion of the positive electrode tab group 21 is cut, or the negative electrode member 24 is joined to the negative electrode tab group 22 and then the excess portion of the negative electrode tab group 22 is removed. If it cut | disconnects, the contact to the case 3 inner surface of those surplus parts can be avoided. 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, the contact of the positive electrode tab group 21 and the negative electrode tab group 22 with the inner surface of the case 3 can be suppressed without performing an operation of cutting such excess portions of the positive electrode tab group 21 and the negative electrode tab group 22.

  (6) Instead of extending the entire one side of the base portion 32a of the specific sheet 32, the protruding portion 32b having a shape in which a portion (the protruding portion 32b) covering the case 3 side of the second bent portion 29 is partially extended. For this reason, the specific sheet 32 can be easily fixed to the electrode assembly 5 by the adhesive tape 33 at the portion where the protruding portion 32b is not formed even at the side where the protruding portion 32b is 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, unlike the insulating sheet, the gap sheet does not necessarily need to be bent. Therefore, a portion covering the case 3 side of the second bent portion 29 of the positive electrode tab group 21 or the negative electrode tab group 22, that is, high strength. The portion required for this can be constituted by the gap sheet 31 made of a hard material (for example, PPS), and the strength of the portion can be appropriately increased. In addition, since the insulating sheet 9b is formed of a relatively soft material (for example, PP), it is possible to suppress an excessively high strength in a required low strength portion. Thus, according to the said secondary battery, the gap | interval sheet | seat 31 and the insulating sheet 9b can be made into the appropriate intensity | strength requested | required of each.

  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.

  The protruding end of the protruding portion 32 b of the specific sheet 32 may be joined to the insulating cover 16. According to such a secondary battery, unnecessary vibration of the specific sheet 32 and displacement of the arrangement position can be suppressed, and the specific sheet 32 can be used between the positive electrode tab group 21 and the case 3 or between the negative electrode tab group 22 and the case 3. Can be suitably insulated from each other.

  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. 9, the entire side of the specific sheet 42 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 is attached to both end faces in the stacking direction L of the electrode assembly 5, and the gap sheet attached to one end face is attached to the second bent portion 29 of the positive electrode tab group 21 and the inner surface of the case 3. The gap sheet attached to the other end face may be extended between the second bent portion 29 of the negative electrode tab group 22 and the inner surface of the case 3.

  As shown in FIG. 10, the protruding portion 52 b of the specific sheet 52 is arranged in the middle of the protruding direction with a 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) and the electrode. You may make it the shape bent so that it may enter into the clearance gap with the assembly 5. FIG. According to such a secondary battery, in addition to performing insulation between the positive electrode tab group 21 (or the negative electrode tab group 22) and the case 3 using the specific sheet 52, the positive electrode tab group 21 (or the negative electrode tab group 22). ) Can be prevented from contacting the electrode assembly 5 unnecessarily.

  In such a secondary battery, the protrusion in the gap of the protrusion 52b of the specific sheet 52 extends farther from the tip of the positive electrode tab group 21 (or negative electrode tab group 22) (to the left side in FIG. 10). preferable. Since the entire electrode assembly 5 side at the tip end side of the second bent portion 29 of the positive electrode tab group 21 (or the negative electrode tab group 22) can be covered by the protruding portion 52b of the gap sheet 32, the gap sheet By 32, the unnecessary contact with the electrode assembly 5 and the part of the front end side of the positive electrode tab group 21 (or negative electrode tab group 22) can be suppressed suitably.

  Further, in such a secondary battery, as shown in FIG. 11, a groove 52 c may be formed in the bent portion of the specific sheet 52. Accordingly, when the specific sheet 52 is disposed, a desired portion can be accurately bent, and thus the disposition is facilitated.

  (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.
○ The structure in which the second bent portion 29 is formed and the specific sheet is extended between the second bent portion 29 and the case 3 is applied to only one of the positive electrode tab group 21 and the negative electrode tab group 22. Also good.

  (Circle) the 2nd bending part 29 does not necessarily need to be provided. For example, when the electrodes 10 and 11 having different lengths of the tabs 15 and 19 are combined to form the electrode assembly 5 and the tab groups 21 and 22, the tabs 15 and 19 are not required to have the second bent portion 29. The excess part of can be shortened. Even in that case, when several tens of tabs (metal foils) are gathered together, it is difficult to accurately manage the bending of each tab 15, 19. An excess part will occur. However, the insulation between the excess portions of the tabs 15 and 19 and the case 3 can be maintained by using the specific sheet 32 made of a hard material.

  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 so as to cover the case 3 side of the second bent portion 29 of the positive electrode tab group 21 (or the negative electrode tab group 22), and between the second bent portion 29 and the case 3 What is necessary is just to make it the shape extended to between.

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 are not limited to those formed integrally with the metal foil forming the electrode, but a piece of rectangular metal foil formed separately and later attached after the active material layer is formed It may be. 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 ... specific sheet, W ... joint.

Claims (6)

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 bent portion bent in one direction, and the bent portion from the bent portion A tab group having an extending part extending in the stacking direction of the electrode assembly, and a joining part provided in the extending part and joined to the conductive member;
A case for housing the conductive member, the electrode assembly, and the tab group;
An electrical storage device comprising an insulating sheet provided between the electrode assembly and the case in a shape covering the periphery of the electrode assembly,
The power storage device has a gap sheet provided between the electrode assembly and the insulating sheet,
The power storage device, wherein the gap sheet extends to the same side as the tab so as to cover a portion of the tab group closer to the tip than the joint portion.   The power storage device according to claim 1, wherein the insulating sheet extends to a position covering the periphery of the tab group.   The power storage device according to claim 1, wherein the gap sheet is made of a material harder than the insulating sheet. The power storage device includes an insulating cover that is provided on the conductive member and insulates between the conductive member and the case.
The power storage device according to claim 1, wherein a tip of the gap sheet is joined to the insulating cover.   A plurality of the gap sheets are provided so as to overlap with each other in the stacking direction, and only the one that is disposed closest to the inner surface side of the case extends between the tab group and the case. Item 5. The power storage device according to any one of Items 1 to 4.   The power storage device according to claim 1, wherein the power storage device is a secondary battery.