JP6031832B2 - Power storage device - Google Patents

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 having a positive electrode active material layer formed on both sides and a negative electrode having a negative electrode active material layer formed on both sides, and an electrode assembly in which these are stacked with a separator in between And a case for accommodating the electrode assembly. Moreover, in order to press the electrode assembly accommodated in the case, for example, in Patent Documents 1 and 2, the peripheral portion is more than the peripheral portion of the facing region where the positive electrode active material layer and the negative electrode active material layer face each other. A configuration is described in which a pressing plate formed smaller than the positive electrode active material layer is provided so as to be inside.

JP 2011-238504 A Japanese Patent Laid-Open No. 11-185820

  By the way, for example, in order to suppress the heat generation of the electrode assembly, it is conceivable to provide a plate-shaped heat transfer portion that performs heat exchange between the electrode assembly and the case. In this case, similarly to the above-described pressing plate, if the heat transfer portion is formed smaller than the facing region (positive electrode active material layer), the load is concentrated on the peripheral portion, and a local load may be applied to the facing region. There is. Then, inconveniences such as generation of precipitates based on ions related to electrical conduction may occur. However, if the heat transfer part is formed larger than the opposing region, the welded part of the lid and the container and the heat transfer part come close to each other, and heat at the time of welding is easily transferred to the electrode assembly via the heat transfer part. Then, inconveniences such as melting of the separator due to the heat may occur.

  The present invention has been made in view of the above-described circumstances, and is capable of suppressing heat transfer related to welding to an electrode assembly while suitably performing heat exchange between the electrode assembly and the case. An object is to provide an apparatus.

In order to achieve the above object, the invention according to claim 1 includes a positive electrode in which a positive electrode active material layer is formed by applying a positive electrode active material, and a negative electrode active material layer by applying a negative electrode active material. An electrical storage device comprising: an electrode assembly formed by stacking a formed negative electrode with a separator interposed therebetween; and a case for housing the electrode assembly, wherein the case is a container opened in one direction And a lid portion that is welded to a peripheral edge portion of the opening portion of the container and closes the opening portion, and the opening portion has a size that allows the electrode assembly to be inserted from the stacking direction, A plate-like heat transfer portion provided between the electrode portion and the electrode assembly, wherein the first surface is in contact with the electrode assembly and the second surface is in contact with the lid portion; When viewed from the direction, the first peripheral edge, which is the peripheral edge of the first surface, Wherein the active material layer or whether the negative electrode active material layers overlap to coincide with the periphery of the facing region facing than the opposing region is located on the outer side, the second peripheral portion is a peripheral edge of the second surface At least one part is located inside the said 1st peripheral part, The said heat-transfer part is formed with one member, It is characterized by the above-mentioned.

According to this invention, since the lid and the electrode assembly are thermally coupled via the heat transfer section, heat exchange between the electrode assembly and the case is possible. And since the 1st peripheral part which is the periphery of the 1st surface seeing from the lamination direction has overlapped with the periphery of the counter area , or is located outside the counter area, the 1st surface is The first peripheral edge can protrude from the opposing area in a state of covering the opposing area. Thereby, even if it is a case where an electrode assembly is pressed by the 1st surface, a local load is hard to be given to an opposing field. Therefore, it is possible to avoid inconveniences such as the generation of precipitates due to the application of a local load to the opposing region, which is a region contributing to charge / discharge.

  In such a configuration, when viewed from the stacking direction, at least a part of the second peripheral edge, which is the peripheral edge of the second surface in contact with the lid, is located inside the first peripheral edge. Thereby, at least one part of a 2nd peripheral part is arrange | positioned so that it may keep away from the welding part of a cover part and a container. Therefore, when heat is applied to the vicinity of the peripheral edge of the opening of the container when the lid and the container are welded, the heat is bypassed by the distance away from the second peripheral edge and is transmitted to the electrode assembly. It will be. Therefore, the heat transfer path between the welded part and the electrode assembly can be lengthened, and the heat transmitted to the electrode assembly through it can be suppressed. Therefore, heat transfer related to welding to the electrode assembly can be suppressed. In addition, a heat transfer part and a cover part may be separate, and may be integral.

  According to a second aspect of the present invention, the opening and the lid have a rectangular shape, and the heat transfer portion has a rectangular shape, and each corner of the heat transfer portion is viewed from the stacking direction. The portion is disposed inside each corner portion of the welded portion between the opening and the lid portion, and at least one corner portion of the corner portions of the heat transfer portion, the second peripheral edge portion is the It exists in the inner side rather than a 1st peripheral part. According to this invention, the welding location has a rectangular frame shape. In this case, in the corner portion where two orthogonal sides intersect, heat at the time of welding is more likely to be concentrated than other portions. For this reason, when viewed from the stacking direction, heat is more easily applied to each corner portion of the heat transfer portion arranged inside the corner portion than other portions.

  In this regard, according to the present invention, at least one of the corner portions of the heat transfer portion is viewed from the stacking direction in correspondence with each corner portion of the welding portion where heat related to welding is likely to concentrate. The 2nd peripheral part is arrange | positioned inside the 1st peripheral part. Thereby, it can suppress more suitably that the heat which concerns on transmission is transmitted to an electrode assembly.

  According to a third aspect of the present invention, in the direction orthogonal to the stacking direction, one end surface of the electrode assembly is provided with a tab protruding from the one end surface, and the heat transfer section is viewed from the stacking direction. Among the corner portions, at least the corner portion located on the opposite surface side of the one end surface of the electrode assembly from which the tab protrudes, the second peripheral edge portion is located on the inner side of the first peripheral edge portion. To do. According to this invention, it is necessary to secure a storage space for the tab between the electrode assembly and the case on one end surface side of the electrode assembly from which the tab protrudes. On the other hand, on the opposite surface side of the one end surface, since it is not necessary to secure a space between the electrode assembly and the case, it is assumed that the electrode assembly and the case are arranged close to each other. In this case, on the facing surface side, the corner portion of the heat transfer portion and the corner portion of the welded portion approach each other.

  In this regard, according to the present invention, when viewed from the stacking direction, the second peripheral edge is disposed on the inner side of the first peripheral edge in the corner located at least on the opposite surface side among the respective corners of the heat transfer section. Therefore, even if the electrode assembly is installed with the corner portion of the heat transfer portion and the corner portion of the welded portion approaching each other on the opposite surface side as described above, the heat associated with welding to the electrode assembly Can be suppressed.

  In the invention according to claim 4, the welded portion of the container and the lid portion surrounds the heat transfer portion, and the entire circumference of the second peripheral edge portion is larger than that of the first peripheral edge portion when viewed from the stacking direction. It is characterized by being inside. According to this invention, the entire circumference of the second peripheral edge portion is located on the inner side of the first peripheral edge portion as viewed from the stacking direction in correspondence with the welding location surrounding the heat transfer portion. Thereby, even if it is a case where welding is performed so that a heat-transfer part may be enclosed, the heat which concerns on the said welding is hard to be transmitted to an electrode assembly. Therefore, in the configuration in which the welding location surrounds the heat transfer portion, the heat transfer related to the welding to the electrode assembly can be more suitably suppressed.

According to a fifth aspect of the present invention, a long positive electrode in which a positive electrode active material layer is formed by applying a positive electrode active material and a long electrode in which a negative electrode active material layer is formed by applying a negative electrode active material. In a power storage device comprising: an electrode assembly that is flatly wound with a negative electrode having a shape sandwiched between separators; and a case that houses the electrode assembly, the electrode assembly in the winding axis direction of the electrode assembly The one end surface is provided with a positive electrode uncoated portion and a negative electrode uncoated portion that protrude from the one end surface and are not coated with each active material, and the case is a flat surface of the electrode assembly. A container having an opening formed on one side; a lid welded to a peripheral edge of the opening and closing the opening; provided between the lid and the electrode assembly; Plate shape that contacts both the flat surface of the electrode assembly and the lid portion A peripheral portion of a rectangular first surface that includes a heat transfer portion and is in contact with the flat surface of the electrode assembly in the heat transfer portion when viewed from an orthogonal direction of the flat surface is the positive electrode active material layer and the negative electrode The facing portion where the active material layer faces and the flat surface overlap with each other so as to coincide with the peripheral edge of the flat facing region , or located outside the flat facing region, and the lid portion of the heat transfer portion A peripheral portion defining one side of the electrode assembly opposite to the uncoated portion side of the rectangular second surface in contact with the non-coated portion of the electrode assembly on the first surface It is inside the peripheral edge part defining one side part opposite to the work part side, and the heat transfer part is formed of one member.

  According to this invention, since the cover part and the flat surface of the electrode assembly are thermally coupled via the heat transfer part, heat exchange between the electrode assembly and the case is possible. And in the state which the 1st surface has covered the flat surface, the peripheral part of the 1st surface can protrude outside a flat opposing area | region seeing from the orthogonal direction of a flat surface. Thereby, even if it is a case where an electrode assembly is pressed by the 1st surface, it is hard to give a local load to a flat opposed region. Therefore, inconveniences such as generation of precipitates due to the application of a local load to the flat opposing region contributing to charging / discharging can be avoided.

  In such a configuration, when viewed from the orthogonal direction of the flat surface, the peripheral edge that defines one side of the second surface opposite to the tab is more than the peripheral edge that defines the one side of the first surface opposite to the tab. Is also inside. As a result, in the side opposite to the tab, when heat is applied to the vicinity of the peripheral edge of the opening of the container when the lid and the container are welded, the heat bypasses the electrode assembly. It will be transmitted. Therefore, the heat transfer path between the welded part and the electrode assembly can be lengthened, and the heat transmitted to the electrode assembly through it can be suppressed. Therefore, heat transfer related to welding to the electrode assembly can be suppressed. In addition, a heat transfer part and a cover part may be separate, and may be integral.

  The invention described in claim 6 is characterized in that the power storage device is a secondary battery.

  According to the present invention, it is possible to suppress heat transfer related to welding to the electrode assembly while suitably performing heat exchange between the electrode assembly and the case.

The front view of the secondary battery which concerns on this invention. The exploded perspective view of an electrode assembly. The exploded perspective view of a secondary battery. 1-1 Line sectional drawing. (A), (b) is sectional drawing which shows the heat-transfer member of a modification. (A) is a front view which shows the secondary battery of a modification, (b) is 2-2 sectional drawing, (c) is 3-3 sectional drawing.

  Hereinafter, a power storage device according to the present invention will be described with reference to FIGS. The power storage device is mounted on a vehicle (automobile and industrial vehicle) and is used to drive a traveling motor (electric motor) mounted on the vehicle.

  As shown in FIG. 1, a secondary battery 10 as a power storage device is a lithium ion secondary battery, and includes a metal case 11 that constitutes an outline thereof. As shown in FIG. 3, the case 11 includes a container 12 having a rectangular box shape (specifically, a rectangular parallelepiped shape). An opening 12 a is formed on one end surface (one side surface) of the container 12. The case 11 includes a lid (lid portion) 13 that closes the opening 12a.

  The case 11 accommodates an electrode assembly 14 as a charge / discharge element and an electrolyte solution (not shown) as an electrolyte. The electrode assembly 14 is formed to be large within a range that can be accommodated in the case 11, and specifically corresponds to the rectangular parallelepiped internal space formed in the case 11, and has a substantially rectangular parallelepiped shape smaller than the internal space. Is formed.

  As shown in FIG. 2, the electrode assembly 14 includes a porous film (a plurality of electrodes, specifically, a plurality of sheet-like positive electrodes 21 and a plurality of sheet-like negative electrodes 22, through which ions related to electrical conduction can pass. For example, the sheet-like separators 23 made of polyethylene resin) are stacked in a sandwiched state.

  Each of the electrodes 21 and 22 and the separator 23 are formed in a rectangular shape (in detail, a rectangular shape), and are similar to each other. The positive electrode 21 is formed slightly smaller than the negative electrode 22, and specifically, the length of each direction of the sheet surface of the positive electrode 21 is set shorter than the length of each direction of the sheet surface of the negative electrode 22. .

  The separator 23 is formed to be slightly larger than the negative electrode 22. Specifically, the length of each direction of the separator 23 is set longer than the length of each direction of the negative electrode 22.

  The positive electrode 21 includes a rectangular positive metal foil (for example, aluminum foil) 21a and a positive electrode active material layer 21b formed by applying a positive electrode active material to both surfaces of the positive electrode metal foil 21a. The positive electrode active material layer 21b is formed in a region other than a part of the sheet surface of the positive electrode 21 (positive metal foil 21a) along the one side portion 21c of the positive electrode 21.

  The negative electrode 22 was formed by applying a negative electrode active material on both surfaces of a rectangular negative electrode metal foil (for example, a copper foil) 22a formed to be slightly larger than the positive electrode metal foil 21a and the negative electrode metal foil 22a. And negative electrode active material layer 22b. The negative electrode active material layer 22b is formed in a region other than a part of the sheet surface of the negative electrode 22 (negative electrode metal foil 22a) along the one side portion 22c of the negative electrode 22, and more than the positive electrode active material layer 21b. Largely formed.

  The electrode assembly 14 is formed by laminating the electrodes 21 and 22 and the separator 23 so that their centers coincide. In this case, the separator 23 overlaps and covers the electrodes 21 and 22. Thereby, each electrode 21 and 22 becomes difficult to short-circuit.

  As shown in FIG. 4, the positive electrode active material layer 21 b and the negative electrode active material layer 22 b face each other with the separator 23 in a state where the electrodes 21 and 22 and the separator 23 are stacked. Specifically, the positive electrode active material layer 21 b is entirely covered with the negative electrode active material layer 22 b with the separator 23 interposed therebetween. A region where the active material layers 21b and 22b face each other (hereinafter referred to as a facing region 24) is a region contributing to charging / discharging. In addition, since the whole positive electrode active material layer 21b is covered with the negative electrode active material layer 22b, the width of the facing region 24 seen from the stacking direction (facing direction) is equal to the width of the positive electrode active material layer 21b. . That is, the positive electrode active material layer 21 b defines the width of the facing region 24.

  As shown in FIG. 1, the electrode assembly 14 is disposed on one end surface (one side surface) in a direction orthogonal to the stacking direction of the electrode assembly 14, specifically, on one end surface 14 a formed by the long sides of the electrodes 21 and 22. Each tab 31 and 32 used for taking out the electric power is provided. As shown in FIG. 2, the tabs 31 and 32 are formed by extending the metal foils 21a and 22a from a part of the side portions 21c and 22c of the electrodes 21 and 22, respectively. The extension dimensions of the tabs 31 and 32 are set so that the tabs 31 and 32 protrude from the separator 23 in a state where the electrodes 21 and 22 and the separator 23 are stacked. Paying attention to the fact that the active material layers 21b and 22b are not formed on the tabs 31 and 32, the positive electrode tab 31 and the negative electrode tab 32 are the positive electrode uncoated portion and the negative electrode uncoated portion where the active material is not applied. It can be said that it is an engineering department.

  For the sake of convenience, in this specification, it is assumed that the positive electrode tab 31 is not included in the positive electrode 21 for the convenience of explanation. Similarly, the negative electrode 22 does not include the negative electrode tab 32.

  Here, as shown in FIG. 1, the electrode assembly 14 is smaller than the case 11 so that a space S in which each tab 31, 32 can be accommodated (installed) is formed in the state accommodated in the case 11. Is formed. Specifically, the length of the electrode assembly 14 in the direction orthogonal to the one end surface 14 a where the tabs 31 and 32 are formed is set to be shorter than the corresponding length in the case 11. And the electrode assembly 14 is accommodated in the state which the other end surface (side surface) 14b as an opposing surface facing the one end surface 14a of the said electrode assembly 14 approached the case 11 (container 12). As a result, a space S is formed between the case 11 and the one end surface 14 a where the tabs 31 and 32 are formed in the electrode assembly 14, and the tabs 31 and 32 are accommodated in the space S.

  The electrodes 21 and 22 are arranged so that their centers coincide with each other, and the same polarity of the tabs 31 and 32 is arranged in a row in the stacking direction, while different polarities do not overlap in the stacking direction. The layers are stacked in consideration of the directions of 21 and 22. As shown in FIG. 3, each positive electrode tab 31 is bent in a state of being collected (bundled) within a range from one end to the other end in the stacking direction of the electrode assembly 14. Specifically, each positive electrode tab 31 is gathered toward one end side (the lid 13 side) of the electrode assembly 14 in the laminating direction, and in the gathered state, the lamination is the side opposite to the one end side. It is folded toward the other end side in the direction. And each positive electrode tab 31 is electrically connected mutually by welding the location where the each positive electrode tab 31 has overlapped. The same applies to the negative electrode tab 32.

  As shown in FIG. 1, the secondary battery 10 includes a positive electrode terminal 41 electrically connected to each positive electrode tab 31 and a negative electrode terminal 42 electrically connected to each negative electrode tab 32. Each terminal 41, 42 is attached in a state of penetrating the case 11 through a through hole formed in a wall portion facing each tab 31, 32 in the container 12, and a part thereof is exposed outside the case 11. doing. Therefore, 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.

  Incidentally, as shown in FIG. 4, the electrode assembly 14 includes an insulating sheet 43 that encloses the stacked body of the electrodes 21 and 22 and the separator 23. As shown in FIG. 3, the insulating sheet 43 covers the electrode assembly 14 other than the one end face 14 a where the tabs 31 and 32 are formed. The electrode assembly 14 is accommodated in the case 11 in a state where the laminated body is covered with the insulating sheet 43. Thereby, the electrode assembly 14 and the case 11 are not short-circuited.

Next, the accommodation mode of the electrode assembly 14 will be described in detail.
As shown in FIG. 3, the opening 12a formed in the container 12 is formed in a rectangular shape corresponding to the electrode assembly 14 formed in a rectangular shape when viewed from the stacking direction. And the opening part 12a is formed in the magnitude | size which can insert the electrode assembly 14 with the tabs 31 and 32 from the lamination direction. The electrode assembly 14 is inserted and accommodated in the container 12 from the stacking direction through the opening 12a.

  The lid 13 that closes the opening 12a is formed in a rectangular plate shape so as to correspond to the opening 12a. As shown in FIG. 4, the peripheral edge 13a of the lid 13 is in contact with the peripheral edge of the opening 12a (the inner surface of the container 12). And the lid | cover 13 and the container 12 are integrated by welding the contact location (for example, laser welding). Thereby, the case 11 is sealed in a state where the electrode assembly 14 is accommodated. In this case, as shown in FIG. 1, a welded portion 51 is formed along the peripheral edge of the opening 12a. That is, the weld location 51 is formed in a frame shape so as to surround the electrode assembly 14.

  Here, as shown in FIG. 3, a heat transfer member 60 used for heat exchange between the electrode assembly 14 and the case 11 is provided between the electrode assembly 14 and the lid 13. . The heat transfer member 60 is configured by overlapping two heat transfer plates 61, 62, specifically, a first heat transfer plate 61 on the electrode assembly 14 side and a second heat transfer plate 62 on the lid 13 side. ing. Each of the heat transfer plates 61 and 62 is formed using a material having a relatively high thermal conductivity, such as aluminum or titanium. Each of the heat transfer plates 61 and 62 is formed so as to correspond to the shape of the electrode assembly 14 (the active material layers 21b and 22b), and specifically, is formed in a rectangular shape. For this reason, the heat transfer member 60 is formed in a rectangular shape as a whole.

  The heat transfer plates 61 and 62 are formed in different sizes. Specifically, as shown in FIGS. 3 and 4, the first heat transfer plate 61 among the heat transfer plates 61 and 62 is formed substantially the same as the one end surface 14 c in the stacking direction of the electrode assembly 14. Yes. Specifically, the first heat transfer plate 61 has the same surface as the sheet surface of the separator 23 constituting the electrode assembly 14. Since the separator 23 is formed larger than the positive electrode 21 and the negative electrode 22, it can be said that the first heat transfer plate 61 is formed larger than the facing region 24 when viewed from the stacking direction. Specifically, when viewed from the stacking direction, the first peripheral edge 61 a that is the peripheral edge of the first heat transfer plate 61 is located outside the facing region 24.

  As shown in FIG. 3, the second heat transfer plate 62 is smaller than the lid 13, specifically, slightly smaller than the first heat transfer plate 61. Specifically, the length in each direction defining the plate surface of the second heat transfer plate 62 is set shorter than the length in each direction defining the plate surface of the first heat transfer plate 61.

  The heat transfer plates 61 and 62 are integrated in a state where the centers of the plate surfaces of the heat transfer plates 61 and 62 coincide with each other. Thereby, the 2nd peripheral part 62a which is the periphery of the 2nd heat exchanger plate 62 is arrange | positioned inside the 1st peripheral part 61a seeing from the lamination direction. That is, the entire peripheral edge portion 60a of the heat transfer member 60 formed by the peripheral edge portions 61a and 62a is formed in a step shape.

  In the heat transfer member 60, corner portions 70a to 70d where two sides in different directions intersect at the peripheral edge portion 60a of the heat transfer member 60 are formed. Each corner part 70 a to 70 d is composed of each corner part 71 a to 71 d of the first heat transfer plate 61 and each corner part 72 a to 72 d of the second heat transfer plate 62. As viewed from the stacking direction, the corner portions 70 a to 70 d of the heat transfer member 60 are arranged at the inside of the corner portions 71 a to 71 d of the first heat transfer plate 61. As a result, a step is formed.

  The heat transfer member 60 includes corner portions 70a to 70d (specifically, the corner portions 71a to 71d of the first heat transfer plate 61), and the corner portions 73a to 73d of the electrode assembly 14 as viewed from the stacking direction. Are accommodated in the case 11 from the first heat transfer plate 61 side in a state in which the directions are aligned so as to match. As shown in FIG. 1, the heat transfer member 60 is surrounded by a welded portion 51, and the corner portions 70 a to 70 d of the heat transfer member 60 are welded portions 51 formed in a frame shape when viewed from the stacking direction. Are arranged inside each of the corner portions 74a to 74d. As shown in FIG. 4, the first surface 61 b that is the plate surface of the first heat transfer plate 61 on the electrode assembly 14 side is the electrode assembly 14, specifically, one end surface 14 c in the stacking direction of the electrode assembly 14. It is in contact with (insulating sheet 43). In this case, the first surface 61b covers the entire one end surface 14c of the electrode assembly 14 in the stacking direction. Focusing on the fact that the opposing region 24 is formed smaller than the one end surface 14c of the electrode assembly 14 when viewed from the stacking direction, it can be said that the first surface 61b overlaps and covers the opposing region 24. Further, the second surface 62 b that is the plate surface of the second heat transfer plate 62 on the lid 13 side is in contact with the lid 13. In addition, it can be said that the 1st peripheral part 61a prescribes | regulates the 1st surface 61b, and the 2nd peripheral part 62a prescribes | regulates the 2nd surface 62b.

  Incidentally, the thickness of the heat transfer member 60 is set equal to or slightly thicker than the distance between the electrode assembly 14 and the lid 13. Thereby, the heat transfer member 60 is accommodated in the case 11 in a state where the electrode assembly 14 is pressed from the stacking direction. The overall thickness of the heat transfer member 60 is, for example, about 1 mm, and the thickness of each of the heat transfer plates 61, 62 is, for example, about 0.5 mm.

Next, the operation of the secondary battery 10 will be described.
As already described, as shown in FIG. 4, the heat transfer member 60 has the first surface 61 b in contact with the electrode assembly 14 and the second surface 62 b in contact with the lid 13. Heat exchange is performed between the electrode assembly 14 and the case 11 via 60. For example, when the electrode assembly 14 generates heat as the electrode assembly 14 is charged and discharged, the heat is transferred to the lid 13 via the heat transfer member 60. Thereby, heat dissipation of the electrode assembly 14 is performed.

  Further, a load is applied to the electrode assembly 14 (opposing region 24) in the stacking direction by the heat transfer member 60. Thereby, the positional deviation of the electrodes 21 and 22 and the separator 23 constituting the electrode assembly 14 is restricted, and the adhesion of the active material layers 21b and 22b is improved.

  Here, as shown in FIG. 4, the first surface 61 b is larger than the facing region 24 (the positive electrode active material layer 21 b), and more specifically, approximately the same size as the one end surface 14 c in the stacking direction of the electrode assembly 14. Is formed. And in the state which the heat-transfer member 60 and the electrode assembly 14 are contacting, the opposing area | region 24 whole is covered with the 1st surface 61b seeing from the lamination direction. Therefore, the first peripheral edge 61a that defines the first surface 61b protrudes outward from the facing region 24 when viewed from the stacking direction, specifically, in a direction orthogonal to the facing direction (stacking direction) of the facing region 24. Yes. Therefore, even when the electrode assembly 14 is pressed by the first surface 61b, load concentration is unlikely to occur in the facing region 24.

  In addition, since the first surface 61b has substantially the same size as the one end surface 14c in the stacking direction of the electrode assembly 14, the first peripheral portion 61a and the peripheral portion of the electrode assembly 14 are viewed from the stacking direction. Are almost identical (see FIG. 1). For this reason, the contact area of the electrode assembly 14 and the heat-transfer member 60 is ensured to the maximum, and heat transfer is improved.

  In particular, the area of the end face 14c in the stacking direction of the electrode assembly 14 is larger than the area of each end face (the end faces 14a, 14b, etc.) in the direction orthogonal to the stacking direction. And the 1st surface 61b is comprised so that the whole end surface 14c of the lamination direction of the electrode assembly 14 may be contacted. Thereby, the maximum contact area between the electrode assembly 14 and the heat transfer member 60 is ensured.

  On the other hand, as shown in FIG. 3, the second peripheral edge 62 a that is the peripheral edge of the second surface 62 b that is in contact with the lid 13 over the entire peripheral edge 60 a of the heat transfer member 60 is viewed from the stacking direction. It arrange | positions inside the 1st peripheral part 61a. For this reason, as shown in FIG. 4, the second peripheral edge portion 62 a is disposed at a position farther from the welding spot 51 than the first peripheral edge portion 61 a. In this case, when heat related to welding is applied to the welded portion 51, it is once transmitted to the second surface 62b via the lid 13 as shown by the arrow in FIG. It will be transmitted. That is, the heat related to welding is bypassed and transmitted to the electrode assembly 14. Thereby, since the heat transfer path is long, heat related to welding is hardly transmitted to the electrode assembly 14.

According to the embodiment described in detail above, the following excellent effects are obtained.
(1) The heat transfer member 60 is provided between the electrode assembly 14 and the lid 13, and the first surface 61 b of the heat transfer member 60 that contacts the electrode assembly 14 is formed on the facing region 24, specifically, the positive electrode active material. The first surface 61b is formed so as to be wider than the layer 21b and overlaps the entire facing region 24. As a result, since the first peripheral edge 61a, which is the peripheral edge of the first surface 61b when viewed from the stacking direction, protrudes outward from the facing region 24, the electrode assembly 14 is pressed by the first surface 61b. Even if it exists, equal pressure is made to the whole opposing area | region 24, and the concentration (uneven load) of the load with respect to the opposing area | region 24 does not occur easily. Thereby, precipitation of lithium resulting from concentration of the load on the facing region 24 can be suppressed.

  Further, the first surface 61b is brought into contact with one end surface 14c in the stacking direction having a relatively large area among the surfaces constituting the electrode assembly 14, and the first surface 61b corresponds to the one end surface 14c in the stacking direction. By making them substantially the same, the maximum contact area between the electrode assembly 14 and the heat transfer member 60 can be secured. Thereby, the improvement of heat conductivity can be aimed at.

  On the other hand, the second peripheral edge 62a, which is the peripheral edge of the second surface 62b that comes into contact with the lid 13, when viewed from the stacking direction, is disposed on the inner side of the first peripheral edge 61a. Accordingly, heat related to welding applied to the weld location 51 is transmitted to the electrode assembly 14 so as to be bypassed, so that heat related to welding is hardly transmitted to the electrode assembly 14. Therefore, inconveniences such as melting of the separator 23 due to heat related to welding can be avoided.

  In particular, in order to secure the opposing region 24 to the maximum extent, the electrode assembly 14 is formed large within a range that can be accommodated in the case 11. In order to suitably perform heat exchange with the electrode assembly 14, the heat transfer member 60 (first surface 61b) is formed to be large corresponding to the electrode assembly 14, and has a relatively high thermal conductivity. (Aluminum etc.) was adopted. For this reason, the heat transfer member 60 is approaching the welding location 51 and is easily affected by the heat associated with welding.

  On the other hand, according to the present embodiment, the distance between the second peripheral edge 62a and the welded part 51 contributes to the length of the heat transfer path (heat transfer path) applied to the welded part 51. Paying attention to this, the second peripheral edge 62a is arranged on the inner side of the first peripheral edge 61a as viewed from the stacking direction so that the transmission path becomes longer. Thereby, in the structure which the heat-transfer member 60 approaches the welding location 51 as mentioned above, the heat transfer which concerns on the welding to the electrode assembly 14 can be suppressed. Therefore, it is possible to suppress the influence of heat related to welding to the electrode assembly 14 while ensuring the opposing region 24 and the heat transfer capability to the maximum.

  (2) The electrode assembly 14 is positively pressed from the stacking direction using the heat transfer member 60. Thereby, while being able to suppress the position shift of each electrode 21 and 22 and the separator 23 which comprise the electrode assembly 14, the improvement of the adhesiveness of each active material layer 21b and 22b can be aimed at. Therefore, the cycle characteristics of the secondary battery 10 can be improved.

  In the above configuration, a load is positively applied to the electrode assembly 14 by positively pressing the electrode assembly 14 using the heat transfer member 60. In such a situation, lithium precipitation or the like due to local concentration of load in the facing region 24 is likely to occur.

  On the other hand, according to the present embodiment, as described above, in the state where the heat transfer member 60 and the electrode assembly 14 are in contact with each other, the first peripheral edge 61 a Therefore, it is possible to avoid the inconvenience that is likely to occur when the heat transfer member 60 is positively pressed. Thereby, the heat-transfer member 60 can be used suitably as a press plate.

  (3) In the configuration in which the electrode assembly 14 is inserted into the case 11 from the stacking direction through the opening 12a of the container 12 and accommodated, the welding location 51 surrounds the heat transfer member 60 when viewed from the stacking direction. Yes. In such a configuration, the second peripheral edge 62a is arranged on the inner side of the first peripheral edge 61a as viewed from the stacking direction over the entire peripheral edge 60a of the heat transfer member 60. Thereby, even if it is a case where the heat-transfer member 60 is surrounded by the welding location 51 on the relationship of the accommodation mode etc. of the electrode assembly 14, the heat which concerns on welding becomes difficult to be transmitted to the electrode assembly 14. FIG. Therefore, heat transfer related to welding to the electrode assembly 14 can be more suitably suppressed.

In addition, you may change the said embodiment as follows.
In the embodiment, the second peripheral edge 62a is disposed on the inner side of the first peripheral edge 61a in the entire peripheral edge 60a of the heat transfer member 60 as viewed from the stacking direction, but the present invention is not limited thereto. In short, it is only necessary that the second peripheral edge 62a is disposed on the inner side with respect to the first peripheral edge 61a in at least a part of the peripheral edge 60a of the heat transfer member 60 when viewed from the stacking direction.

  ○ For example, in a specific portion of the peripheral portion 60a of the heat transfer member 60, specifically, in a portion where the heat of welding is particularly concentrated, the second peripheral portion 62a is more than the first peripheral portion 61a when viewed from the stacking direction. It is good also as a structure arrange | positioned inside. Specifically, as shown in FIG. 1, for example, when viewed from the stacking direction, each corner portion 74 a to 74 d of the welded portion 51 where heat is likely to concentrate by crossing two different sides at the welded portion 51. Moreover, in each corner part 70a-70d of the heat-transfer member 60, it is good also as a structure which arrange | positions the 2nd peripheral part 62a inside the 1st peripheral part 61a. Specifically, the corner portions 72 a to 72 d of the second heat transfer plate 62 may be arranged inside the corner portions 71 a to 71 d of the first heat transfer plate 61 when viewed from the stacking direction.

  Moreover, it is good also as a structure which arrange | positions the 2nd peripheral part 62a inside the 1st peripheral part 61a seeing from the lamination direction in at least 1 corner part among each corner part 70a-70d of the heat-transfer member 60. . For example, when viewed from the stacking direction, each corner positioned on the other end surface 14b (side surface) side that is the facing surface of the one end surface 14a from which at least the tabs 31 and 32 protrude among the corner portions 70a to 70d of the heat transfer member 60. In the parts 70c and 70d, it is good also as a structure which arrange | positions the 2nd peripheral edge part 62a inside the 1st peripheral edge part 61a. In detail, it is good also as a structure which arrange | positions each corner part 72c, 72d of the 2nd heat exchanger plate 62 inside each corner part 71c, 71d of the 1st heat exchanger plate 61 seeing from the lamination direction.

  That is, as shown in FIG. 1, each corner part 70a, 70b of the heat-transfer member 60 located in each tab 31 and 32 side (one end surface 14a side) sees the welding location 51 corresponding to these seeing from the lamination direction. Although they are inside the corner portions 74a and 74b, they are separated from each other by the space S for accommodating the tabs 31 and 32. On the other hand, the corner portions 70c and 70d of the heat transfer member 60 located on the side of the other end surface 14b opposite to the tabs 31 and 32 side, and the corner portions 74c and 74d of the welded portions 51 corresponding thereto are shown. It is close. For this reason, it is easy to receive the influence of the heat which concerns on welding.

  On the other hand, according to the above configuration, at least the corner portions 70c and 70d that are easily affected by heat in the heat transfer member 60, the second peripheral edge 62a is more than the first peripheral edge 61a when viewed from the stacking direction. By arrange | positioning inside, the heat transfer which concerns on the welding to the electrode assembly 14 can be suppressed.

  Similarly, in the region other than the region on the tabs 31 and 32 side (specifically, the region between the corner portions 70a and 70b) of the peripheral edge portion 60a of the heat transfer member 60 as viewed from the stacking direction, It is good also as a structure which arrange | positions the 2 peripheral part 62a inside the 1st peripheral part 61a.

  ○ As described above, in the configuration in which the second peripheral edge 62a is disposed inside the first peripheral edge 61a in a part of the peripheral edge 60a of the heat transfer member 60 when viewed from the stacking direction, In this area, the second peripheral edge 62a and the first peripheral edge 61a may be arranged at the same position, and the second peripheral edge 62a may be arranged outside the first peripheral edge 61a. Thereby, the heat transfer can be further improved through the area improvement of the second surface 62b while suppressing the influence of heat related to welding.

  In embodiment, although the heat-transfer member 60 was comprised with the two heat-transfer plates 61 and 62, it is not restricted to this, You may be formed with one member and is comprised with three or more members. May be.

  O Moreover, although the peripheral part 60a of the heat-transfer member 60 became stepped shape, it is not restricted to this. In short, the heat transfer member only needs to be tapered from the electrode assembly 14 side toward the lid 13 side. For example, as shown in FIG. 5A, the peripheral portions 61 a and 62 a are connected to each other, and an inclined portion 81 that is inclined inward toward the lid 13 from the electrode assembly 14 is formed. There may be. Further, for example, as shown in FIG. 5B, a curved portion 82 that is curved from the first peripheral edge portion 61 a toward the second peripheral edge portion 62 a may be provided.

In short, as long as the second peripheral edge 62a is inside the first peripheral edge 61a when viewed from the stacking direction, the specific shape connecting the peripheral edges 61a and 62a is arbitrary.
In the embodiment, the electrode assembly 14 is a stacked type in which the positive electrode 21 and the negative electrode 22 are alternately stacked with the separator 23 interposed therebetween, but is not limited thereto. For example, as shown in FIGS. 6B and 6C, an electrode in which a strip-like positive electrode 91 and a negative electrode 92 extending in one direction are wound with a strip-like separator 93 interposed therebetween. An assembly 90 may be used. Specifically, as illustrated in FIG. 6C, the electrode assembly 90 includes a positive electrode 91 including a positive electrode active material layer 91b, a negative electrode 92 including a negative electrode active material layer 92b, and two separators interposed therebetween. A band 94 constituted by overlapping 93 is wound flatly. As shown in FIG. 6B, the electrode assembly 90 has a flat shape when viewed from the winding axis direction, and is formed on both sides of the flat surface 90a and the flat surface 90a in the winding direction. And a curved surface 90b.

  As shown in FIGS. 6A and 6B, the electrode assembly 90 is inserted into the opening 12a from the flat surface 90a and accommodated in the case 11. In this case, as shown in FIG. 6B, one side of the flat surface 90 a faces the lid 13.

  In this configuration, as shown in FIG. 6B, the heat transfer member 100 includes two rectangular heat transfer plates, a first heat transfer plate 101 on the electrode assembly 90 side and a second heat transfer plate 102 on the lid 13 side. The hot plates 101 and 102 are configured to overlap each other. The first surface 101 b of the first heat transfer plate 101 is in contact with the entire flat surface 90 a, and the second surface 102 b of the second heat transfer plate 102 is in contact with the lid 13.

  As shown in FIG. 6A, the length of the first heat transfer plate 101 in the winding axis direction is set to be the same as the length of the flat surface 90a in the winding axis direction. Moreover, as shown in FIG.6 (b), the length of the winding direction in the 1st heat exchanger plate 101 is set longer than that of the flat surface 90a. The heat transfer member 100 is attached between the electrode assembly 90 and the lid 13 with the first surface 101b of the first heat transfer plate 101 in contact with the entire flat surface 90a. That is, as shown in FIG. 6B and FIG. 6C, the first peripheral edge portion 101a, which is the peripheral edge of the first heat transfer plate 101 (first surface 101b), is viewed from the orthogonal direction of the flat surface 90a. The positive electrode active material layer 91b and the negative electrode active material layer 92b are positioned outside the flat counter area 110 where the counter area where the positive electrode active material layer 92b opposes and the flat plane 90a overlap.

  Here, the peripheral edge portion 100a of the heat transfer member 100 is flat with no steps except for the portion opposite to the tabs 31 and 32 side. Specifically, the peripheral portions 101a and 102a of the heat transfer plates 101 and 102 constituting the heat transfer member 100 are heat transfer members except for the one side portions 101aa and 102aa on the side opposite to the tabs 31 and 32 side. They are arranged at the same position as viewed from the thickness direction of 100. On the other hand, as shown in FIG. 6C, in each of the one side portions 101aa and 102aa, the second one side portion 102aa constituting the second peripheral edge portion 102a is first viewed from the thickness direction of the heat transfer member 100. It arrange | positions inside 1st one side part 101aa which comprises 1 peripheral part 101a.

  According to such a configuration, since the second one side portion 102aa is disposed on the inner side than the first one side portion 101aa when viewed from the orthogonal direction of the flat surface 90a (the stacking direction in the flat surface 90a), the tabs 31 and 32 are provided. On the side opposite to the side, the gap between the welded portion 51 and the second one side portion 102aa is wide. Thereby, even when heat is applied to the welded part 51, the heat is not easily transmitted to the electrode assembly 90.

  On the other hand, on the side where the tabs 31 and 32 are provided, the heat transfer member 100 and the welded portion 51 are separated from each other by the space S relating to the accommodation of the tabs 31 and 32. Further, as shown in FIG. 6B, the curved surface 90b of the electrode assembly 90 is disposed inside the welded portion 51 on both ends of the flat surface 90a in the winding direction. Since the curved surface 90b is separated from the welded portion 51, the peripheral edge portion 100a of the heat transfer member 100 is located at the same position when viewed from the orthogonal direction of the flat surface 90a except for the portion opposite to the tabs 31 and 32 side. Even if it is arrange | positioned, the heat which concerns on welding is hard to be transmitted to the electrode assembly 90. FIG. Therefore, it is possible to improve the heat transfer property by expanding the area of the second heat transfer plate 102 while suppressing the heat transfer related to the welding to the electrode assembly 90.

  In this example, the first peripheral edge portion 101a is located outside the flat facing area 110 when viewed from the direction orthogonal to the flat face 90a. However, the first peripheral edge portion 101a is not limited to this and overlaps the flat facing area 110. It may be.

  In the embodiment, the first heat transfer plate 61 is formed larger than the positive electrode 21 (positive electrode active material layer 21b) and the negative electrode 22 (negative electrode active material layer 22b), but is not limited thereto. In short, it is only necessary to have a size that can cover a relatively small active material layer among the active material layers 21b and 22b. For example, the negative electrode active material layer within a range that can cover the positive electrode active material layer 21b. You may form smaller than 22b. That is, when viewed from the stacking direction, the first peripheral edge 61a, which is the peripheral edge of the first heat transfer plate 61, overlaps with the positive electrode active material layer 21b having the same size as the facing region 24, or is positioned outside of it. Just do it.

  In the embodiment, the thickness of each of the heat transfer plates 61 and 62 is set to be substantially the same, but may be configured to be different. For example, the thickness of the second heat transfer plate 62 may be greater than the thickness of the first heat transfer plate 61.

  In embodiment, although the electrically-conductive member was employ | adopted as the heat-transfer member 60, it is not restricted to this, You may employ | adopt an insulating member. In this case, the insulating sheet 43 may be omitted at a location where the electrode assembly 14 contacts the heat transfer member 60. Thereby, the heat transfer can be improved through direct contact between the laminate and the heat transfer member 60 without the insulating sheet 43 interposed. In this case, the sheet constituting the outermost layer of the laminated body constitutes one end surface 14 c of the electrode assembly 14 in the lamination direction.

  In embodiment, although the electrode assembly 14 was the structure accommodated in the case 11 from the lamination direction via the opening part 12a, it is not restricted to this. For example, an opening may be provided in a direction orthogonal to the stacking direction in the case 11, the electrode assembly 14 may be inserted from the opening, and the opening may be closed with a lid. Even in this case, a heat transfer member may be provided between the electrode assembly 14 and the lid.

  In embodiment, although the welding location 51 was formed in the end surface (side surface) 14c of the lamination direction in case 11, it is not restricted to this, The structure formed in the end surface of the direction orthogonal to the lamination direction in case 11 It is good. In addition, as a specific configuration in which the welded portion is formed on the end surface of the case 11 in the direction orthogonal to the stacking direction, for example, the lid is formed slightly larger than the opening 12a of the container, and the inner surface of the lid 13 and the container 12 The structure welded in the state which face | matched the front-end | tip surface can be considered.

  In embodiment, although the heat-transfer member 60 and the lid | cover 13 were provided as a different body, it is not restricted to this, You may integrate both. In this case, a part of the lid 13 functions as the heat transfer member 60.

  In the embodiment, laser welding is adopted as a welding mode of the container 12 and the lid 13, but the invention is not limited thereto, and any welding may be performed as long as predetermined heat is applied. For example, resistance welding, arc discharge welding, or the like may be used.

In the embodiment, the negative electrode 22 and the separator 23 are formed in different sizes. However, the present invention is not limited to this, and for example, both may be formed in the same size.
In embodiment, although the positive electrode 21 was formed smaller than the negative electrode 22, it is not restricted to this, For example, you may form both in the same magnitude | size.

  In the embodiment, the electrodes 21 and 22 and the separator 23 are stacked in a state where the centers coincide with each other. However, the present invention is not limited to this. When the electrodes 21 and 22 are stacked with the separator 23 and the positive electrode active material layer 21b covered with the negative electrode active material layer 22b, the centers are shifted (for example, two adjacent sides overlap). The structure may be a layered state.

  In the embodiment, each of the electrodes 21 and 22 and the separator 23 has a rectangular shape, but is not limited thereto, and may be a square shape. Further, the shape is not limited to a rectangular shape, and may be another shape (for example, a polygonal shape other than a rectangular shape or an elliptical shape).

The separator 23 may be made of any material as long as the separator 23 is a porous film capable of passing lithium ions while suppressing short circuits between the electrodes 21 and 22.
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.
(A) The positive electrode active material layer is narrower than the negative electrode active material layer, and the whole of the positive electrode active material layer is covered with the negative electrode active material layer in a state where the electrodes are stacked, and the first surface Is wider than the positive electrode active material layer so as to cover at least the entire positive electrode active material layer as the facing region. 7. The power storage device according to claim 1.

(B) The power storage unit according to any one of claims 1 to 6 and the technical idea (a), wherein the heat transfer section presses the electrode assembly from the stacking direction. apparatus.
(C) When viewed from the stacking direction, the welded portion of the container and the lid portion surrounds the heat transfer portion, and the second peripheral edge in the region other than the tab side in the peripheral portion of the heat transfer portion The power storage device according to claim 3, wherein the portion is inside the first peripheral edge.

  DESCRIPTION OF SYMBOLS 10 ... Secondary battery as a power storage device, 11 ... Case, 12 ... Container, 13 ... Lid, 14 ... Electrode assembly, 21 ... Positive electrode, 22 ... Negative electrode, 23 ... Separator, 24 ... Opposite region, 31, 32 ... Tab , 43 ... Insulating sheet, 51 ... Welded part, 60 ... Heat transfer member, 60a ... Peripheral part of heat transfer member, 61 ... First heat transfer plate, 61a ... Peripheral part of first heat transfer plate, 61b ... First surface , 62 ... the second heat transfer plate, 62a ... the peripheral portion of the second heat transfer plate, 62b ... the second surface, 70a to 70d ... each corner portion of the heat transfer member, 73a to 73d ... each corner portion of the electrode assembly, 74a to 74d ... corner portions of welding locations, 90 ... another electrode assembly, 90a ... flat surface, 100 ... another heat transfer member, 101a ... another first peripheral portion, 102a ... another example 2 peripheral edge portions, 101b ... first surface of another example, 102b ... second surface of another example, 110 ... flat opposing region

Claims (6)

A positive electrode in which a positive electrode active material layer is formed by applying a positive electrode active material and a negative electrode in which a negative electrode active material layer is formed by applying a negative electrode active material are stacked with a separator in between. An electrode assembly comprising:
A case for housing the electrode assembly;
In a power storage device comprising:
The case is
A container opened in one direction;
A lid that is welded to the periphery of the opening of the container and closes the opening;
With
The opening is sized such that the electrode assembly can be inserted from the stacking direction;
A plate-shaped heat transfer portion provided between the lid portion and the electrode assembly, having a first surface in contact with the electrode assembly and a second surface in contact with the lid portion;
Seen from the stacking direction of the electrode assembly,
The first peripheral edge, which is the peripheral edge of the first surface , overlaps with the peripheral edge of the opposing area where the positive electrode active material layer and the negative electrode active material layer face each other, or is positioned outside the opposing area. And at least a part of the second peripheral edge, which is the peripheral edge of the second surface, is located on the inner side of the first peripheral edge, and the heat transfer part is formed of one member. A power storage device. The opening and the lid have a rectangular shape, and the heat transfer portion has a rectangular shape,
Seen from the stacking direction,
Each corner portion of the heat transfer portion is disposed inside each corner portion of the welded portion between the opening and the lid portion, and at least one corner portion of the corner portions of the heat transfer portion, 2. The power storage device according to claim 1, wherein the second peripheral edge is located inside the first peripheral edge. In a direction orthogonal to the stacking direction, a tab protruding from the one end surface is provided on one end surface of the electrode assembly,
When viewed from the stacking direction, at least one of the corner portions of the heat transfer portion, the corner portion located on the opposite surface side of the one end surface of the electrode assembly from which the tab protrudes, the second peripheral edge portion is the first edge portion. The power storage device according to claim 2, wherein the power storage device is located inside the peripheral portion. The welded part of the container and the lid part surrounds the heat transfer part,
4. The power storage device according to claim 1, wherein when viewed from the stacking direction, the entire circumference of the second peripheral edge is on the inner side of the first peripheral edge. 5. An elongated positive electrode having a positive electrode active material layer formed by applying a positive electrode active material and an elongated negative electrode having a negative electrode active material layer formed by applying a negative electrode active material are interposed between separators. An electrode assembly wound flat in a sandwiched state;
A case for housing the electrode assembly;
In a power storage device comprising:
One end surface in the winding axis direction of the electrode assembly is provided with a positive electrode uncoated portion and a negative electrode uncoated portion that are projected from the one end surface and not coated with the active materials,
The case is
A container having an opening formed on one side of the flat surface of the electrode assembly;
A lid that is welded to a peripheral edge of the opening and closes the opening;
With
A plate-shaped heat transfer portion provided between the lid portion and the electrode assembly, and in contact with both the flat surface of the electrode assembly and the lid portion;
Seen from the orthogonal direction of the flat surface,
In the heat transfer portion, a peripheral portion of the rectangular first surface that is in contact with the flat surface of the electrode assembly overlaps the flat region and a facing region where the positive electrode active material layer and the negative electrode active material layer face each other. It overlaps with the peripheral edge of the flat facing area or is located outside the flat facing area,
The peripheral edge part defining one side part of the electrode assembly opposite to the uncoated part side in the rectangular second surface contacting the lid part of the heat transfer part is the first surface. A power storage device, wherein the heat transfer unit is formed of a single member inside a peripheral edge that defines one side opposite to each uncoated part of the electrode assembly.   The power storage device according to claim 1, wherein the power storage device is a secondary battery.