JP2013229173A - Power storage device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a power storage device capable of sufficiently restraining displacement of a first electrode sheet and each separator section.SOLUTION: A secondary battery is provided with an electrode assembly 14 constituted by alternately laminating sheet aggregates 20 and negative electrode sheets 22. The sheet aggregate 20 comprises a positive electrode sheet 21, and a pair of separators 23, 24 covering both faces of the negative electrode sheet 22. A recess section 73 indented toward a second end 21e from a first end 21c is formed at the first end 21c of the positive electrode sheet 21, and a first welding section 61 connecting the pair of separators 23, 24 is provided in the recess section 73. A second welding section 62 is provided on a second end 21e side opposite to the first end 21c.

Description

  The present invention relates to a power storage device.

  A vehicle such as an EV (Electric Vehicle) or a PHV (Plug in Hybrid Vehicle) is equipped with a secondary battery as a power storage device that stores power supplied to the traveling motor. The secondary battery includes, for example, a positive electrode sheet and a negative electrode sheet having active material layers formed on both surfaces, and an electrode assembly in which these are stacked with a separator interposed therebetween. As a lamination mode of this electrode assembly, for example, in Patent Document 1, a first electrode sheet (first electrode sheet accommodated in a first separator portion and a second separator portion which are formed into a bag shape as a whole by heat-welding the end portions ( It describes an aspect in which positive electrode sheets) and second electrode sheets (negative electrode sheets) are alternately laminated.

JP 2009-218105 A

  However, in the aspect in which the first electrode sheet is surrounded by the welded portions as described above, it is possible to suppress the positional deviation between the first electrode sheet and each separator part, and for example, the electrolyte intrudes into each separator part. May be hindered by the welding location, and the time required for impregnation of the electrolyte into each separator portion may be increased. For this reason, there is still room for improvement with respect to the configuration relating to the positional deviation suppression of the first electrode sheet and each separator portion.

  This invention is made | formed in view of the situation mentioned above, and aims at providing the electrical storage apparatus which can suppress suitably the position shift with a 1st electrode sheet and each separator part.

  In order to achieve the above object, the invention according to claim 1 covers the first electrode sheet, the first separator portion covering one surface of the first electrode sheet, and the other surface of the first electrode sheet. In a power storage device including an electrode assembly in which a second separator portion and a second electrode sheet having a polarity different from that of the first electrode sheet are stacked, the first electrode sheet includes a first end, A second end opposite to the first end; and a recess recessed from the first end toward the second end is formed in the first end. The separator portion has a first connection portion and a second connection portion connected to the second separator portion, at least a part of the first connection portion is formed in the recess, and the second connection portion is It is formed on the second end side.

  According to this invention, the movement of the first electrode sheet with respect to each separator portion in the facing direction of each connection portion (each end portion) is regulated by the contact between each connection portion and the first electrode sheet. Furthermore, movement of the first electrode sheet with respect to each separator portion in a direction orthogonal to the facing direction is restricted by contact between the first connection portion and the side surface of the recess. Thereby, the position shift of the 1st electrode sheet with respect to each separator part can be suppressed, without providing a connection part in the site | part of the direction orthogonal to the said opposing direction in each separator part.

  According to a second aspect of the present invention, an active material layer coated with an active material is formed on at least one surface of the first electrode sheet, and the active material is not coated on the first electrode sheet. The coated portion is formed along the first end portion and has a width in a direction perpendicular to the first end portion, and at least a part of the concave portion is formed in the uncoated portion. It is characterized by that. The region in the recess is a region that does not contribute to charging / discharging. In this regard, according to the present invention, since the concave portion is formed using the uncoated portion that does not contribute to charging / discharging, it is possible to suppress the expansion of the region that does not contribute to charging / discharging caused by forming the concave portion. it can. Thereby, coexistence with suppression of position shift and suppression of the expansion of the area | region which does not contribute to charging / discharging resulting from the structure for the said position shift suppression can be aimed at.

  The invention according to claim 3 is characterized in that the first electrode sheet is a positive electrode sheet and the second electrode sheet is a negative electrode sheet. In general, the positive electrode sheet is formed smaller than the negative electrode sheet in order to suppress deposits of ions related to electrical conduction. Moreover, each separator part is formed larger than the 1st electrode sheet of the object to cover, in order to suppress the contact (short circuit) of each electrode sheet. In this regard, according to the present invention, the size of each separator can be reduced by adopting a positive electrode sheet that is relatively easily formed as the first electrode sheet. Thereby, size reduction of an electrode assembly can be achieved.

  The invention according to claim 4 is characterized in that the first connecting portion is a welded portion in which the first separator portion and the second separator portion are welded. According to this invention, it is possible to realize the connection of the separator portions relatively easily by adopting welding as a mode of connecting the separator portions. In this case, the electrolyte impregnation may be hindered by the welded portion. In addition, when heat is applied during welding, each separator portion may shrink and wrinkles may be formed. In this regard, according to the present invention, since the number of welding locations can be reduced by providing the first connection portion in the recess, the above-described inconvenience can be avoided.

  According to a fifth aspect of the present invention, the second connection portion is separated from the first separator portion and the second separator portion by a predetermined distance along end portions of the first separator portion and the second separator portion. It is characterized by being a plurality of welded portions in which the separator portions are welded. According to this invention, the position shift with respect to each separator part of a 1st electrode sheet is more suitably controlled by the some welding part. On the other hand, since the electrolyte can enter from the gaps between the welded portions, it is possible to prevent the time required for the impregnation of the electrolyte from increasing.

  In the invention according to claim 6, the first separator part and the second separator part are formed by folding an integrated separator, and the second connection part is formed by folding the separator. It is a folded portion. According to this invention, the area | region which the structure concerning a connection occupies can be made small by employ | adopting a folding | turning part as a 2nd connection part. Thereby, the area | region which contributes to charging / discharging can be enlarged.

  The invention according to claim 7 is characterized in that the power storage device is a secondary battery.

  According to this invention, the position shift between the first electrode sheet and each separator part can be suitably suppressed.

The perspective view of a secondary battery. The exploded perspective view of an electrode assembly. (A) is an enlarged view around a 1st welding part, (b) is the sectional view on the AA line of (a). The front view for demonstrating the manufacturing method of a sheet | seat aggregate. (A)-(c) is the elements on larger scale which show the modification of a recessed part. (A) is a disassembled perspective view which shows the modification of a sheet assembly, (b-1), (b-2) is explanatory drawing for demonstrating the manufacturing method of the sheet assembly of a modification.

  Hereinafter, a power storage device according to the present invention will be described with reference to FIGS. A plurality of the power storage devices are mounted on vehicles (automobiles and industrial vehicles), and are used to drive a traveling motor (electric motor) mounted on the vehicle. In addition, about FIG.3 (b), the sectional view on the AA line of Fig.3 (a) in the state which has not fracture | ruptured the separator 23 is shown.

  A secondary battery 10 as a power storage device is a lithium ion secondary battery, and includes a metal case 11 that forms an outer shell of the battery as shown in FIG. The case 11 includes a rectangular box-shaped container 12 and a rectangular flat lid 13 that closes the opening of the container 12. For this reason, the secondary battery 10 has a rectangular outer shape.

  The case 11 contains an electrode assembly 14 and an electrolytic solution (not shown) as an electrolyte. As shown in FIG. 2, the electrode assembly 14 is formed by alternately stacking a plurality of sheet assemblies 20 and a plurality of negative electrode sheets 22 that are configured so that the plurality of sheets are not displaced. The sheet assembly 20 is formed such that a positive electrode sheet 21 as a first electrode sheet and ions (lithium ions) related to electrical conduction can pass therethrough and sandwich the positive electrode sheet 21 in a state of covering both surfaces of the positive electrode sheet 21. Separators 23 and 24.

  Each of the electrode sheets 21 and 22 and the pair of separators 23 and 24 is formed in a rectangular shape (in detail, a rectangular shape). The positive electrode sheet 21 is formed slightly smaller than the negative electrode sheet 22. Specifically, the length of each direction of the positive electrode sheet 21 is set shorter than the length of each direction of the negative electrode sheet 22. Each of the pair of separators 23 and 24 is formed to be slightly larger than the negative electrode sheet 22. Specifically, the length of each direction of the separators 23 and 24 is longer than the length of each direction of the negative electrode sheet 22. Is set.

  The positive electrode sheet 21 includes a positive electrode metal foil (for example, an aluminum foil) 21a and a positive electrode active material layer 21b formed by applying a positive electrode active material on both surfaces of the positive electrode metal foil 21a. The negative electrode sheet 22 as the second electrode sheet includes a negative electrode metal foil (for example, copper foil) 22a and a negative electrode active material layer 22b formed by applying a negative electrode active material on both surfaces of the negative electrode metal foil 22a. Has been. By laminating the sheet aggregate 20 and the negative electrode sheet 22, the positive electrode active material layer 21b and the negative electrode active material layer 22b are opposed to each other with the pair of separators 23 and 24 interposed therebetween. A region where the active material layers 21b and 22b face each other is a region contributing to charge / discharge.

  The positive electrode sheet 21 of the sheet assembly 20 at both ends in the stacking direction of the electrode assembly 14 has a positive electrode active material layer 21b formed only on one surface (inner surface). For this reason, it is avoided that the area | region which does not oppose the negative electrode active material layer 22b in the positive electrode active material layer 21b is formed. However, the present invention is not limited to this, and for example, the negative electrode sheets 22 may be provided at both ends of the electrode assembly 14. In this case, in order to suppress a short circuit between the negative electrode sheet 22 and the container 12 provided at both ends, an insulating coating is applied to the surface of the negative electrode sheet 22 or the inner surface of the container 12, or between the negative electrode sheet 22 and the container 12. It is good to insert a separator.

  As shown in FIG. 2, the positive electrode sheet 21 has a positive electrode-side uncoated portion 21 d to which a positive electrode active material is not applied along the first end portion 21 c (one side direction (longitudinal direction)) of the positive electrode sheet 21. Is formed. The positive electrode-side uncoated portion 21 d is formed to have a width in the other side direction (short direction) of the positive electrode sheet 21. A positive electrode current collecting tab 31 formed by extending the positive electrode metal foil 21 a is provided on one side of the first end 21 c of the positive electrode sheet 21. In the present embodiment, the pair of separators 23 and 24 protrude beyond the end of the positive electrode sheet 21 in the direction along the surface of the positive electrode sheet 21 except for the portion of the positive electrode current collecting tab 31. Therefore, the pair of separators 23 and 24 cover most of the positive electrode sheet 21.

  Similarly to the positive electrode sheet 21, the negative electrode sheet 22 is provided with a negative electrode side uncoated portion 22 d to which the negative electrode active material is not applied along the end portion 22 c of the negative electrode sheet 22. The negative electrode side uncoated portion 22 d is formed with a width in the short direction of the negative electrode sheet 22. The width of the negative side uncoated portion 22d is set shorter than the width of the positive side uncoated portion 21d. A negative electrode current collecting tab 32 formed by extending the negative electrode metal foil 22a is provided at a part of the end 22c of the negative electrode sheet 22 opposite to the positive electrode current collecting tab 31. The current collecting tabs 31 and 32 are gathered together by laminating the plurality of sheet aggregates 20 and the plurality of negative electrode sheets 22.

  As shown in FIG. 1, the lid 13 of the case 11 is provided with a positive terminal 41 and a negative terminal 42 and connects the same polarities of the terminals 41 and 42 and the current collecting tabs 31 and 32. A positive electrode 51 and a negative electrode 52 are provided. Thereby, the electric power of the electrode assembly 14 can be taken out of the case 11 and the electrode assembly 14 can be charged by supplying electric power to the electrode assembly 14.

Next, a configuration for suppressing the displacement of the positive electrode sheet 21 and the pair of separators 23 and 24 in the sheet assembly 20 will be described.
As shown in FIG. 2, the sheet assembly 20 is integrated by connecting the pair of separators 23 and 24 in a state where the positive electrode sheet 21 is sandwiched between the pair of separators 23 and 24. Specifically, a first weld formed at two opposite ends of the pair of separators 23 and 24 (sheet assembly 20) is assumed to connect the pair of separators 23 and 24 to the sheet assembly 20. A part 61 (first connection part) and a second welding part 62 (second connection part) are provided. In other words, it can be said that one separator 23 has a first welded portion 61 and a second welded portion 62 connected to the other separator 24, and the other separator 24 is connected to one separator 23. It can be said that the first welded portion 61 and the second welded portion 62 are provided.

  The first welded portion 61 is provided on each end 23 a, 24 a side, which is the first end 21 c side of the positive electrode sheet 21, of the pair of separators 23, 24 in the short direction. The second welded portion 62 is provided on each end 23b, 24b side opposite to the end 23a, 24a side where the first welded portion 61 is provided. In the following description, the end portions 23a, 24a on the side where the first welded portion 61 is provided in the pair of separators 23, 24 are collectively referred to as the first separator end portion 71, and the second welded portion 62. The end portions 23b and 24b on the side where the head is provided are collectively referred to as a second separator end portion 72.

  First, the first welded portion 61 will be described in detail. As shown in FIGS. 2 and 3A, the first end portion 21 c on the side where the positive electrode side uncoated portion 21 d is formed in the positive electrode sheet 21. Is formed with a recess 73 that is recessed from the first end 21c toward the second end 21e. The recess 73 is formed near the center of the first end 21 c of the positive electrode sheet 21. The concave portion 73 has a shape in which two inclined sides intersect at one point, and specifically has a V shape when viewed from the front. In other words, it can be said that the recess 73 is open toward the first end portion 21 c of the positive electrode sheet 21, and the direction along the surface of the positive electrode sheet 21 from the first end portion 21 c of the positive electrode sheet 21. It can also be said that it is a thing dented toward the inner side (direction orthogonal to the said 1st edge part 21c) (direction orthogonal to the lamination direction of the electrode assembly 14). A part of the recess 73 enters the positive electrode active material layer 21b. That is, the recess 73 is formed across the positive electrode side uncoated portion 21d and the positive electrode active material layer 21b. The concave portion 73 may be formed integrally when the positive electrode sheet 21 is punched out by pressing, or may be formed by cutting out separately.

  The first welded portion 61 is at least partially formed in the recess 73. In the present embodiment, most of the first welded portion 61 is interposed in the region where the recess 73 is formed. A part of the first welded portion 61 protrudes from the recess 73. As shown in FIG. 3B, the first welded portion 61 is a portion where the pair of separators 23 and 24 are thermally welded. As shown in FIG. 3A, the first welded portion 61 is in contact with the side surfaces 73 a and 73 b that form the recess 73. That is, the 1st welding part 61 is pinched | interposed by the side surfaces 73a and 73b from the direction orthogonal to the opposing direction of each welding part 61 and 62 (specifically the longitudinal direction of the positive electrode sheet 21).

  Here, as already described, the length of the positive electrode sheet 21 in the short direction is shorter than the length of the pair of separators 23 and 24 in the short direction. For this reason, as shown in FIG. 2, in the situation where the positive electrode sheet 21 is arranged so that the first welded portion 61 enters the recess 73, the first welded portion 61 is formed in the pair of separators 23 and 24. The second separator end 72 on the opposite side of the first separator end 71 protrudes beyond the second end 21 e of the positive electrode sheet 21. And the 2nd welding part 62 to which the pair of separators 23 and 24 were heat-welded in the protruded area | region is formed. A plurality of second welds 62 are formed at predetermined intervals in the longitudinal direction of the pair of separators 23 and 24.

Next, the operation of the secondary battery 10 according to the present invention will be described.
As shown in FIG. 2, a first welded portion 61 and a second welded portion 62 are provided to face each other, and the positive electrode sheet 21 is sandwiched between these welded portions 61 and 62. Thereby, the positive electrode sheet 21 faces the pair of separators 23 and 24 in the facing direction of the welded portions 61 and 62, specifically, the facing direction of the end portions 21 c and 21 e of the positive electrode sheet 21 (the short direction of the positive electrode sheet 21). ) Is not misaligned. Note that if the positive electrode current collecting tab 31 is formed at the first end portion 21 c in the short direction of the positive electrode sheet 21, it can be said that the facing direction is a direction in which the positive electrode current collecting tab 31 is pulled out.

  Furthermore, the 1st welding part 61 is pinched | interposed from the longitudinal direction of the positive electrode sheet 21 by each side surface 73a, 73b of the recessed part 73 (refer Fig.3 (a)). Thereby, the positive electrode sheet 21 is prevented from being displaced in the longitudinal direction (a direction orthogonal to the drawing direction of the positive electrode current collecting tab 31) with respect to the pair of separators 23 and 24. Thereby, it is not necessary to provide the welding part which connects each separator 23 and 24 and regulates position shift of the positive electrode sheet 21 at both ends in the longitudinal direction of the pair of separators 23 and 24.

From the above, the positive electrode sheet 21 is not displaced with respect to the pair of separators 23 and 24.
In addition, as shown in FIG. 2, the width | variety along the transversal direction of the negative electrode side uncoated part 22d is set shorter than the width | variety along the transversal direction of the positive electrode side uncoated part 21d. For this reason, when the electrode sheets 21 and 22 are laminated with the end portions 21c and 22c formed with the uncoated portions 21d and 22d aligned, the positive electrode active material layer 21b and the negative electrode active material layer 22b Non-opposing areas do not occur.

  Next, a method for manufacturing the secondary battery 10 according to the present invention will be described. First, after describing the manufacturing method of the sheet assembly 20 included in the manufacturing method of the electrode assembly 14 with reference to FIG. 4, the manufacturing method of the secondary battery 10 will be described.

  First, as shown in FIG. 4, two strip-shaped separator bases S1 and S2 are prepared as materials for the pair of separators 23 and 24. The width (length in the short direction) of each separator base S <b> 1, S <b> 2 is set longer than the length in the short direction of the positive electrode sheet 21. Then, the separator bases S1 and S2 are arranged so as to overlap with the positive electrode sheet 21 interposed therebetween. Thereafter, as shown by the one-dot chain line in FIG. 4, the separator bases S <b> 1 and S <b> 2 are cut according to the lengths of the separators 23 and 24 in the longitudinal direction. At this time, in the pair of separator bases S1 and S2, the first welding region 81 that overlaps the concave portion 73 of the positive electrode sheet 21 and a plurality of second electrodes that are opposite to the first welding region 81 and that do not overlap the positive electrode sheet 21. The heat treatment is performed on the two welding regions 82. Thereby, the welding parts 61 and 62 are formed, and the positive electrode sheet 21 is prevented from being displaced with respect to the pair of separators 23 and 24.

  In addition, when each welding area | region 81 and 82 is heat-processed, each said welding area | region 81 and 82 becomes an area | region (shutdown area | region) through which lithium ion cannot pass. That is, it is difficult for the welded portions 61 and 62 to pass lithium ions.

Further, the cutting and the heat treatment may be performed at the same time or may be performed separately. In this case, heat treatment may be performed after cutting, or vice versa.
After the sheet aggregate 20 is formed, the sheet aggregate 20 and the negative electrode sheet 22 are alternately stacked. Thereby, as shown in FIG. 1, the electrode assembly 14 is formed. Then, the electrode assembly 14 is accommodated in the case 11, and an electrolytic solution is injected from an injection port 83 formed in the lid 13 of the case 11. Then, the injection port 83 is sealed by the sealing portion 84. Then, it waits until electrolyte solution fully impregnates in the sheet | seat assembly 20, specifically the positive electrode sheet 21 and a pair of separators 23 and 24 (impregnation process). Thereafter, the secondary battery 10 is manufactured by performing various processes such as conditioning.

The effect | action of the manufacturing method of the secondary battery 10 which concerns on this invention is demonstrated.
The sheet assembly 20 composed of the positive electrode sheet 21 and the pair of separators 23 and 24 is prepared in advance, and the sheet assembly 20 and the negative electrode sheet 22 are stacked. Need not be laminated.

  Moreover, electrolyte solution can penetrate | invade except the location in which each welding part 61 and 62 is provided among each side part in the sheet | seat aggregate 20. FIG. For this reason, the electrolytic solution easily enters the sheet assembly 20.

  The positive electrode sheet 21 is formed by punching out a positive metal band with a mold that forms the outer shape of the positive electrode sheet 21. In this case, the mold is preliminarily molded so that the recess 73 is formed when punched. Thereby, it is not necessary to perform a special process for forming the recess 73.

According to the embodiment described in detail above, the following excellent effects are obtained.
(1) A sheet assembly 20 including a positive electrode sheet 21 and a pair of separators 23 and 24 covering both surfaces of the positive electrode sheet 21 is formed, and the sheet assembly 20 and the negative electrode sheet 22 are stacked. . Thereby, by laminating the sheet aggregate 20, the positive electrode sheet 21 and the pair of separators 23 and 24 are naturally laminated. Thereby, compared with the structure which laminates | stacks the positive electrode sheet 21 and a pair of separators 23 and 24 separately, lamination | stacking time can be shortened.

  In such a configuration, the first end 21 c of the positive electrode sheet 21 is formed with a recess 73 that is recessed from the first end 21 c toward the second end 21 e, and a pair of separators that sandwich the positive electrode sheet 21 in the recess 73. The 1st welding part 61 which connects 23 and 24 was formed. And the 2nd welding part 62 is formed in the opposite side (the 2nd edge part 21e side of the positive electrode sheet 21) in the pair of separators 23 and 24, and the positive electrode sheet 21 is each welding part 61,62. It was set as the structure pinched | interposed by. As a result, the positions of the positive electrode sheet 21 in the opposing direction (short direction) of the welded portions 61 and 62 with respect to the pair of separators 23 and 24 are restricted by the welded portions 61 and 62. And the position shift of the positive electrode sheet 21 in the direction (longitudinal direction) orthogonal to the opposing direction with respect to the pair of separators 23 and 24 is regulated by the contact between the first welded portion 61 and the side surfaces 73a and 73b of the recess 73. Has been. Thereby, without forming the welding location for regulating the position shift of the positive electrode sheet 21 at the end in the longitudinal direction of the pair of separators 23 and 24, the positive electrode sheet 21 in each direction with respect to the pair of separators 23 and 24 is formed. Misalignment can be suppressed. Therefore, the welding location which does not contribute to charging / discharging can be reduced, and the fall of an energy density can be suppressed through it. Moreover, electrolyte solution can penetrate | invade except the formation location of each welding part 61 and 62 among each side part of the sheet | seat aggregate 20. FIG. Thereby, the electrolytic solution is easily impregnated in the sheet assembly 20. Therefore, the time required for the impregnation step can be shortened.

  (2) As a mode of connecting the pair of separators 23 and 24, by adopting relatively easy welding, both can be easily connected. In particular, thermal welding is a relatively easy connection method and high strength, but it is difficult for the electrolytic solution to pass through the welded portion. For this reason, the time of an impregnation process tends to become long. Moreover, in order to ensure a welding location, it may be necessary to form the positive electrode sheet 21 small. Furthermore, when heat is applied for welding, the pair of separators 23 and 24 contract and wrinkles are generated.

On the other hand, according to this embodiment, since the welding location for restricting the position shift of the positive electrode sheet 21 can be reduced, the above inconvenience can be avoided.
(3) On the positive electrode sheet 21, a positive electrode-side uncoated portion 21d on which no positive electrode active material was applied was formed. And the recessed part 73 was taken as the structure currently formed in the positive electrode side uncoated part 21d. Thereby, since the recessed part 73 is formed using the positive electrode side uncoated part 21d which is an area | region which does not contribute to charging / discharging, it does not contribute to charging / discharging which can arise by providing the structure for suppressing position shift. Expansion of the area can be suppressed.

  (4) The positive electrode sheet 21 was adopted as the electrode sheet constituting the sheet assembly 20. Here, the positive electrode sheet 21 is formed smaller than the negative electrode sheet 22 so as not to form a region that does not face the negative electrode active material layer 22b in the positive electrode active material layer 21b. Moreover, a pair of separators 23 and 24 need to be formed larger than the object sheet | seat to cover, in order to ensure the space for the contact of each electrode sheet 21 and 22, and welding.

  In this regard, according to the present embodiment, by using the relatively small positive electrode sheet 21 as the target sheet, the pair of separators 23 and 24 can be made smaller than the configuration in which the negative electrode sheet 22 is the target sheet. it can. Therefore, the sheet assembly 20 can be reduced in size.

  (5) As the second connection portion, a plurality of second welded portions 62 formed at predetermined intervals along the second separator end portion 72 are employed. Thereby, the position shift of the positive electrode sheet 21 can be suppressed more suitably. Moreover, since electrolyte solution can penetrate | invade from the clearance gap between the 2nd welding parts 62, it can suppress that the time of an impregnation process becomes long.

  In particular, when the first welded portion 61 formed in the recess 73 is employed as the first connection portion, a gap may be formed between the first welded portion 61 and the recess 73 depending on the heat treatment mode and the like. In this case, displacement of the positive electrode sheet 21 in the longitudinal direction or the rotation direction may occur. On the other hand, according to the present embodiment, by forming the plurality of second welded portions 62, even when the gap is generated, the positional deviation of the positive electrode sheet 21 in each direction is suppressed. Can do.

  (6) The width of the negative side uncoated part 22d was set shorter than the width of the positive side uncoated part 21d. Thus, when the electrode sheets 21 and 22 are laminated with the end portions 21c and 22c formed with the current collecting tabs 31 and 32 aligned, the positive electrode active material layer 21b faces the negative electrode active material layer 22b. It is possible to prevent the area not to be generated.

  The positive electrode sheet 21 is disposed so as to be displaced in the short direction with respect to the pair of separators 23 and 24 (specifically, closer to the first separator end portion 71) in order to secure a space for the second welding portion 62. ing. In this case, when viewed from the front, the distance between the first separator end 71 and the first end 21c of the positive electrode sheet 21 is larger than the distance between the second separator end 72 and the second end 21e of the positive electrode sheet 21. Narrow (see FIG. 4). For this reason, if the negative electrode sheet 22 is arranged closer to the first separator end 71 than the positive electrode sheet 21 in order to suppress lithium deposition, the negative electrode sheet 22 contacts the positive electrode sheet 21 across the separators 23 and 24. There is a risk.

  On the other hand, according to the present embodiment, the negative electrode sheet 22 is set to be shorter than the positive electrode sheet 21 by setting the width of the negative electrode side uncoated portion 22d to be shorter than the width of the positive electrode side uncoated portion 21d. There is no need to dispose it near the end 71 of the separator. Thereby, the said contact can be avoided.

In addition, you may change the said embodiment as follows.
In the embodiment, the concave portion 73 is formed in a V shape, but is not limited thereto, and the positive electrode sheet 21 is orthogonal (crossed) to the facing direction of each welded portion 61, 62 (short direction of the positive electrode sheet 21). As long as it is formed so as to restrict the displacement of the positive electrode sheet 21 in the direction (longitudinal direction), the specific configuration thereof is arbitrary. For example, as shown in FIG. 5 (a), a concave portion 91 having a trapezoidal shape whose width is gradually shortened inward may be used, and as shown in FIG. 5 (b), a square shape is formed. The concave portion 92 may be used. Moreover, as shown in FIG.5 (c), the curved recessed part 93 may be sufficient.

  In addition, in the embodiment, the recess 73 is formed across the positive electrode side uncoated portion 21d and the positive electrode active material layer 21b, but is not limited thereto. For example, the concave portion 93 shown in FIG. 5C is formed only in the positive electrode-side uncoated portion 21d and is not formed in the positive electrode active material layer 21b. Thereby, the area | region which contributes to charging / discharging by the recessed part 93 is not reduced.

  In the embodiment, the plurality of second welding portions 62 are employed as the second connection portion, but the present invention is not limited to this, and the specific welding mode is arbitrary. For example, a configuration in which the entire end portions 23b and 24b of the pair of separators 23 and 24 are thermally welded may be used. It is good also as a structure.

  In the embodiment, the first welded portion 61 is configured to come into contact with the side surfaces 73a and 73b of the concave portion 73, but is not limited thereto, and the positive electrode sheet 21 does not protrude from the pair of separators 23 and 24. Within the range, a gap may be formed between the first welded portion 61 and the side surfaces 73 a and 73 b of the recess 73.

  In embodiment, it was set as the structure which covers the positive electrode sheet 21 with a pair of separators 23 and 24, However, It is not restricted to this. For example, the sheet assembly 101 in the electrode assembly 100 shown in FIG. 6A is formed by folding an integrated separator 102 and sandwiching the positive electrode sheet 111 between the separators 102. In this case, the folded portion 102 a formed by folding the separator 102 functions as the second welded portion 62. Specifically, the movement of the positive electrode sheet 111 in the short direction (opposite direction between the first welded portion 61 and the folded portion 102a) is restricted by the first welded portion 61 and the folded portion 102a.

  That is, the separator constituting the sheet assembly may be a pair of separators 23 and 24 as in the embodiment as long as both surfaces of the positive electrode sheet are covered, or the integrated separator 102 as described above. May be. In other words, the first separator portion covering one surface of the positive electrode sheet and the second separator portion covering the other surface may be separate members or a single member.

  Here, the width of the folded portion 102 a is shorter than that of the second welded portion 62. For this reason, the area | region which contributes to charging / discharging can be expanded. Specifically, as shown in FIG. 6A, the length of the positive electrode sheet 111 sandwiched between the separators 102 is longer than the positive electrode sheet 21 (see FIG. 2) of the embodiment. . Specifically, the lengths in the short direction of the positive electrode metal foil 111a and the positive electrode active material layer 111b are set longer than those in the embodiment. Thereby, the area | region which contributes to charging / discharging is expanding.

  In addition, the manufacturing method of the sheet assembly 101 will be described. First, as shown in FIG. 6B-1, the positive electrode sheets 111 are sequentially inserted in a state where the integrated separator base S3 is folded. Then, as shown in FIG. 6 (b-2), both sides of the positive electrode sheet 111 are cut in the separator base S 3, and the first welding region 81 is subjected to heat treatment. Thereby, the sheet aggregate 101 is formed.

  In the embodiment, welding is adopted as the connection mode of the separators 23 and 24. However, the present invention is not limited to this, and the specific mode is arbitrary as long as it can be connected. For example, it is good also as a structure made to adhere | attach using an adhesive agent or an adhesive tape, and it is good also as a structure which provides a latching | locking part in each separator 23 and 24, and connects by latching, and connects each separator 23 and 24 by sewing. It is good also as composition to do.

  In embodiment, although the recessed part 73 was formed in the 1st end part 21c by which the positive electrode side uncoated part 21d is formed among each edge part of the positive electrode sheet 21, it is not restricted to this, 2nd edge part It may be formed at another end such as 21e.

In the embodiment, the welded portions 61 and 62 are formed to face each other in the short direction of the pair of separators 23 and 24. However, the present invention is not limited to this, and the welded portions 61 and 62 may be formed to face each other in the longitudinal direction.
In embodiment, although the positive electrode sheet 21 was employ | adopted as what comprises the sheet | seat aggregate | assembly 20, it is not restricted to this, You may employ | adopt the negative electrode sheet 22. FIG. In this case, a recess 73 may be formed in the end 22c of the negative electrode sheet 22 on the side where the negative electrode side uncoated portion 22d is formed.

In embodiment, although the recessed part 73 was formed in the center of the 1st end part 21c of the positive electrode sheet 21, it is not restricted to this, The position currently formed is arbitrary.
O Moreover, the recessed part 73 is not restricted to one, A plurality may be formed.

  Further, most of the first welded portion 61 is interposed in the recess 73, but the entire first welded portion 61 may be interposed in the recess 73. Moreover, the part which protrudes from the recessed part 73 in the 1st welding part 61 may be most. In short, it is only necessary that at least a part of the first welded portion 61 is accommodated in the recess 73.

  In the embodiment, the width of the negative electrode-side uncoated portion 22d is set to be shorter than the width of the positive electrode-side uncoated portion 21d. However, the present invention is not limited to this, and both may be set to be the same. Further, the negative electrode side uncoated portion 22d may be omitted.

  In the embodiment, the negative electrode sheet 22 is formed to be smaller than the separators 23 and 24, but is not limited thereto, and may be formed to be the same as or larger than the separators 23 and 24. Moreover, you may make the positive electrode sheet 21 and the negative electrode sheet 22 the same magnitude | size.

The positive electrode active material layer 21b may be formed only on one surface of the positive electrode metal foil 21a.
In embodiment, although the secondary battery 10 was a lithium ion secondary battery, it is not restricted to this, Other secondary batteries, such as nickel hydride, may be sufficient. 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.

In the embodiment, the secondary battery 10 is mounted on the vehicle, but is not limited thereto, and may be mounted on another device.
The present invention may be applied to other power storage devices such as electric double layer capacitors.

Next, the technical idea that can be grasped from the above embodiment and other examples will be described below.
(B) A gap through which an electrolyte can enter is formed at an end portion of each separator portion in a direction orthogonal to the facing direction of each connection portion. The power storage device according to one item.

  DESCRIPTION OF SYMBOLS 10 ... Secondary battery as a power storage device, 14 ... Electrode assembly, 20 ... Sheet assembly, 21 ... Positive electrode sheet, 21c ... First end portion, 21e ... Second end portion, 21d ... Positive electrode side uncoated portion, 22 ... negative electrode sheet, 22d ... negative electrode side uncoated part, 23, 24 ... separator, 61, 62 ... welded part, 71 ... first separator end part, 72 ... second separator end part, 73 ... concave part, 101 ... separate Example sheet assembly, 102... Another example separator, 102 a.

Claims (7)

A first electrode sheet;
A first separator portion covering one surface of the first electrode sheet;
A second separator portion covering the other surface of the first electrode sheet;
A second electrode sheet having a polarity different from that of the first electrode sheet;
In a power storage device including an electrode assembly in which are stacked,
The first electrode sheet has a first end and a second end opposite to the first end,
The first end is formed with a recess recessed from the first end toward the second end,
The first separator part has a first connection part and a second connection part connected to the second separator part,
At least a portion of the first connection portion is formed in the recess;
The power storage device, wherein the second connection portion is formed on the second end side. An active material layer coated with an active material is formed on at least one surface of the first electrode sheet,
The first electrode sheet is formed with a width in a direction perpendicular to the first end portion along the first end portion with an uncoated portion to which the active material is not applied,
The power storage device according to claim 1, wherein at least a part of the recess is formed in the uncoated portion.   The power storage device according to claim 1, wherein the first electrode sheet is a positive electrode sheet, and the second electrode sheet is a negative electrode sheet.   The power storage device according to any one of claims 1 to 3, wherein the first connection portion is a welded portion in which the first separator portion and the second separator portion are welded.   The second connection portion includes a plurality of welded portions of the first separator portion and the second separator portion at predetermined intervals along the end portions of the first separator portion and the second separator portion. It is a welding part, The electrical storage apparatus as described in any one of Claims 1-4 characterized by the above-mentioned. The first separator part and the second separator part are formed by folding an integrated separator,
The power storage device according to any one of claims 1 to 4, wherein the second connection portion is a folded portion formed by folding the separator.   The power storage device according to claim 1, wherein the power storage device is a secondary battery.