JP2023180724A - Power storage device - Google Patents

Abstract

To provide a power storage device that can improve cooling performance while preventing thermal damage to power storage elements in welding a conductive member.SOLUTION: A power storage device comprises: a first power storage element and a second power storage element that have a cylindrical shape and are adjacent to each other; a housing member that has thermal conductivity and houses the first power storage element and the second power storage element; and a conductive member that electrically connects the first power storage element and the second power storage element to each other. The first power storage element has an end face electrode at an axial end. The second power storage element has a peripheral face electrode on an outer peripheral part. The conductive member extends from the end face electrode toward the peripheral face electrode to be connected with the end face electrode and the peripheral face electrode. The conductive member has a thick part at a portion facing the end face electrode, and an end face-side thin part having a smaller thickness than the thick part. The end face-side thin part is connected by welding with the end face electrode. The power storage device has a structure to release heat of the end face electrode to the housing member through the conductive member and the peripheral face electrode.SELECTED DRAWING: Figure 1

Description

The present invention relates to a power storage device.

For example, Patent Document 1 discloses a power storage device including a power storage element having an external terminal and a bus bar connected to the external terminal. The bus bar has a thin portion at a portion facing the external terminal. The thin wall portion and the external terminal are welded.

International Publication No. 2014/050329

Incidentally, in order to reduce the cost of power storage devices, it is desired to reduce the number of power storage elements. However, when the number of power storage elements is reduced, the value of current flowing through the power storage elements increases. Then, the amount of heat generated by the power storage element increases, and there is a high possibility that the temperature will reach the upper limit of the specification. Therefore, improving the cooling performance of power storage devices has become a challenge.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a power storage device that can improve cooling performance while suppressing thermal damage to a power storage element when welding a conductive member.

The power storage device according to one aspect of the present invention has a cylindrical shape, has a first power storage element and a second power storage element that are adjacent to each other, has thermal conductivity, and has a first power storage element and a second power storage element that are adjacent to each other. A storage member for storing the electricity storage element, and a conductive member electrically connecting the first electricity storage element and the second electricity storage element, wherein the first electricity storage element has an end surface electrode at an axial end, and the first electricity storage element has an end surface electrode at an axial end. 2. The electricity storage element has a circumferential electrode on the outer circumference, and the conductive member extends from the end electrode toward the circumferential electrode to be connected to the end electrode and the circumferential electrode, and The conductive member has a thick portion in a portion facing the end electrode, and an end thin portion thinner than the thick portion, and the end thin portion is welded and connected to the end electrode. The structure is such that heat from the end electrode is released to the housing member via the conductive member and the peripheral electrode.

According to the above aspect, cooling performance can be improved while suppressing thermal damage to the power storage element when welding the conductive member.

FIG. 1 is an exploded perspective view of a power storage device according to an embodiment. FIG. 2 is an exploded perspective view of a power storage element and a conductive member according to an embodiment before assembly. FIG. 2 is a perspective view of an assembled power storage element and a conductive member according to an embodiment. FIG. 2 is a perspective view of the power storage device according to the embodiment after being assembled. FIG. 3 is an explanatory diagram of welding locations of the conductive member according to the embodiment. FIG. 3 is a diagram showing a portion facing an end electrode in a conductive member according to an embodiment. FIG. 2 is a side view of a conductive member according to an embodiment. FIG. 3 is a diagram showing a portion of the conductive member according to the embodiment that faces a peripheral electrode. FIG. 3 is a diagram for explaining a structure in which heat from an end electrode is released to a storage member via a conductive member and a peripheral electrode. FIG. 7 is a diagram showing the cooling effect of the conductive member of the example together with a comparative example.

Embodiments of the present invention will be described below with reference to the drawings. In the embodiment, a power storage device applied to a working machine such as a capacitor-equipped shovel will be cited as an example of the power storage device. In excavators equipped with capacitors, it is desired to reduce the number of power storage elements in order to reduce costs.

<Power storage device>
FIG. 1 is an exploded perspective view of a power storage device 1 according to an embodiment. FIG. 2 is an exploded perspective view of the power storage element 11 and the conductive member 100 according to the embodiment before assembly. FIG. 3 is a perspective view of the power storage element 11 and the conductive member 100 after being assembled according to the embodiment. FIG. 4 is a perspective view of the power storage device 1 according to the embodiment after being assembled.
Power storage device 1 includes power storage element 11 , storage member 27 , conductive member 100 , and cooling mechanism 60 . In the illustrated example, power storage device 1 includes twelve (one example of a plurality of) power storage elements 11. These power storage elements 11 are electrically connected to adjacent power storage elements 11 through conductive members 100 . In the embodiment, all twelve power storage elements 11 are connected in series.

<Electricity storage element>
For example, the power storage element 11 is an electric double layer capacitor that has a large capacity and excellent rapid charging and discharging characteristics. Power storage element 11 has a cylindrical shape. Hereinafter, the direction along the central axis of the cylindrical shape of the power storage element 11 is also referred to as the "axial direction," the direction perpendicular to the central axis as the "radial direction," and the direction around the central axis as the "circumferential direction."

The power storage element 11 has an end surface electrode 15 at the end in the axial direction. In the embodiment, the end electrode 15 is a positive electrode. The power storage element 11 has a circumferential electrode 17 on the outer periphery. In the embodiment, the peripheral electrode 17 is a negative electrode. The power storage element 11 has a cylindrical casing with a bottom. The casing forms the cylindrical shape of the power storage element 11. For example, the casing is formed by extrusion molding a metal plate such as an aluminum plate. The peripheral electrode 17 is constituted by a cylindrical portion of the casing.

Note that since the bottom of the casing (the bottom surface of the power storage element 11) is also molded integrally with the cylindrical part of the casing (the circumferential surface of the power storage element 11), it serves as a negative electrode. In the embodiment, electrical connection to the bottom surface of the power storage element 11 is not made. Although not shown, an insulating material is interposed between the end surface electrode 15 and the peripheral surface electrode 17. Thereby, electrical insulation between the end surface electrode 15 and the peripheral surface electrode 17 is maintained.

<Conductive member>
The conductive member 100 is a member (bus bar) that electrically connects adjacent power storage elements 11 to each other. For example, the conductive member 100 is formed by press-molding a metal plate such as an aluminum plate. The conductive member 100 has a substantially L-shape. A portion 120 of the conductive member 100 facing the circumferential electrode 17 is bent into a shape along the outer periphery of the circumferential electrode 17, and has a curved shape along the outer periphery of the circumferential electrode 17. The conductive member 100 extends radially outward from a portion facing the end electrode 15 and then extends toward the circumferential electrode 17 via the bent portion 130 .

The bent portion 130 includes a portion 111 of the conductive member 100 that faces the end surface electrode 15 (hereinafter also referred to as the “end surface side facing portion 111”) and a portion 120 that faces the peripheral surface electrode 17 (hereinafter referred to as the “surrounding surface side facing portion 120”). ). Thereby, even if there is a positional shift when welding and connecting the end surface side facing portion 111 of the conductive member 100 to the end surface electrode 15 of the adjacent power storage element 11, it can be absorbed by the bent portion 130. In addition, even if vibrations are applied to the entire power storage device 1 after assembly from the outside, the stress applied to the welded connection portion between the end face side facing portion 111 and the end face electrode 15 can be alleviated by the bent portion 130. Therefore, it is possible to reduce the possibility that the welded portion between the end face side facing portion 111 and the end face electrode 15 will come off due to vibration, and good vibration resistance can be obtained.

In the embodiment, the peripheral surface side facing portion 120 of the conductive member 100 has a shape that matches the outer periphery of the peripheral surface electrode 17 of the power storage element 11 . Therefore, by welding and connecting the circumferential surface-side facing portion 120 and the circumferential electrode 17 in a state where they match, it is possible to achieve highly reliable electrical and mechanical connection.

In the embodiment, for a plurality of power storage elements 11 in which a conductive member 100 is welded and connected at a circumferential side facing part 120, an end face electrode 15 of an adjacent power storage element 11 and an end face side facing part 111 of the conductive member 100 are welded and connected. By doing so, six power storage elements 11 per column are connected in series. For example, this welding is performed using a jig that can accurately position the end face electrode 15 of each power storage element 11 to be in contact with the end face facing portion 111 of the adjacent conductive member 100. In the embodiment, all 12 power storage elements 11 are connected in series by using two rows of six power storage elements 11 connected in series. For this purpose, the conductive member 100 at the right end of the rear row shown in FIG. 1 is welded and connected with its direction rotated by 90 degrees so as to overlap the end surface electrode 15 at the right end of the front row.

Note that in the power storage element 11, the adjacent conductive member 100 does not exist on the end face electrode 15 at the left end of the rear row shown in FIG. Therefore, the positive electrode terminal 25 for power input/output of all the power storage elements 11 is welded and connected to the end face electrode 15 at the left end of the rear row shown in FIG. The positive electrode terminal 25 has a plate shape for causing the circumferential surface side facing portion 120 of the conductive member 100 to function as the end surface side facing portion 111. For example, like the conductive member 100, the positive electrode terminal 25 is formed by press-molding a metal plate such as an aluminum plate.

On the other hand, the adjacent end surface electrode 15 does not exist on the conductive member 100 at the left end of the front row in FIG. 1 in the power storage element 11 . Therefore, this conductive member 100 functions as the negative electrode terminal 26 for power input/output of all the power storage elements 11.

<Storage components>
The storage member 27 has thermal conductivity. For example, the storage member 27 is made of metal such as aluminum. The storage member 27 is a member (holder) for storing the plurality of power storage elements 11. The storage member 27 also functions as a heat sink that performs cooling by dissipating heat from the power storage element 11 to the outside.

The storage member 27 has a configuration in which a metal rectangular parallelepiped is provided with a plurality of arcuate concave surfaces 29 (12 in the embodiment) for storing a portion of the circumferential surface of the power storage element 11 . The storage member 27 has a fixing plate screw hole 31 for screwing the fixing plate 39 and a case screw hole 33 for screwing the case 47.

The concave surface 29 is formed to have a substantially semicircular shape when the storage member 27 in FIG. 1 is viewed from above. For example, the storage member 27 is formed by extrusion molding, cutting, or the like.

In the embodiment, the concave surface 29 is provided so that the power storage elements 11 are not stacked in bales. Thereby, the heat capacity of the storage member 27 can be increased. In addition, since a part of the storage member 27 is interposed between two adjacent power storage elements 11, the interval between the power storage elements 11 is widened. For this reason, it is possible to make each of the power storage elements 11 less susceptible to the effects of heat generation from other power storage elements 11 . As a result, good heat dissipation is obtained.

A portion of the circumferential surface of the power storage element 11 is accommodated in the concave surface 29 of the storage member 27 . For example, the portion of the circumferential surface of the power storage element 11 that is accommodated in the concave surface 29 and the concave surface 29 of the storage member 27 are bonded using a bonding material 35 having insulation properties (hereinafter also referred to as "insulating bonding material 35"). has been done. Thereby, when a plurality of power storage elements 11 are stored in the metal storage member 27, it is possible to prevent the circumferential electrodes 17 from being electrically short-circuited.

For example, the insulating bonding material 35 may be double-sided tape. For example, the circumferential surface of the power storage element 11 can be joined to the concave surface 29 by pasting double-sided tape on the circumferential surface of the power storage element 11 that is accommodated in the concave surface 29 and then storing it in the storage member 27. In the example of FIG. 1, approximately half of the area of the circumferential surface of the power storage element 11 is fixed by the concave surface 29 and the insulating bonding material 35. Note that a double-sided tape may be attached to the concave surface 29 of the storage member 27, and then the power storage element 11 may be stored therein.

In the embodiment, the insulating bonding material 35 is entirely embedded in the gap between the circumferential surface of the power storage element 11 and the concave surface 29 of the storage member 27 after bonding with the insulating bonding material 35 . Thereby, the heat of the power storage element 11 is transmitted to the storage member 27 via the insulating bonding material 35. Therefore, efficient heat radiation becomes possible. Further, in the embodiment, heat is radiated by a metal storage member 27 having a larger heat capacity than the power storage element 11. Therefore, even if the power storage element 11 is frequently charged and discharged, the possibility that a specific power storage element 11 disposed in the central portion of the power storage device 1 or the like will be overheated can be reduced.

The double-sided tape as the insulating bonding material 35 has a laminated structure of a base material and adhesive parts formed on both sides of the base material. For example, the base material is preferably an elastic resin (eg, foil-like rubber). Thereby, the entire gap formed between the power storage element 11 and the concave surface 29 having different radii can be filled with the double-sided tape. Therefore, efficient heat radiation becomes possible.

For example, it is preferable that the adhesive part contains an insulating and thermally conductive filler made of ceramic such as alumina or silica. As a result, even if the power storage element 11 is strongly pushed into the concave surface 29 or the base material is cut due to progressing deterioration, the insulating and thermally conductive filler contained in the adhesive part will protect the power storage element 11. It is interposed between the peripheral surface and the concave surface 29. Therefore, it is possible to reduce the possibility of a short circuit caused by the peripheral surface of the power storage element 11 coming into direct contact with the concave surface 29. Therefore, both high heat dissipation and high reliability can be achieved.

In the embodiment, the power storage element 11 housed in the housing member 27 is further held by a fixing plate 39. For example, the fixing plate 39 is made of resin. The fixing plate 39 has a holding part 41 for storing and holding a part of the cylindrical circumferential surface of the power storage element 11. The holding portion 41 has six arcuate concave surfaces. The holding portion 41 is formed so as to provide a slight gap between the storage member 27 and the fixing plate 39 while holding the power storage element 11 housed in the concave surface.

For example, when attaching the storage member 27 to the fixing plate 39, eight fixing plate screws 43 are tightened into the fixing plate screw holes 31 so that there is no gap between the storing member 27 and the fixing plate 39. Thereby, the elasticity of the resin of the fixing plate 39 holds the power storage element 11 so as to push it into the storage member 27 side. As a result, the power storage element 11 is joined to the storage member 27 with double-sided tape and is firmly held by the elasticity of the fixing plate 39. Therefore, even if the power storage device 1 is applied to applications where vibration is noticeable (for example, hybrid construction machinery, etc.), the possibility that the power storage element 11 will come off or the connection of the conductive member 100 will be cut is reduced, and a good Provides vibration resistance.

In the embodiment, a bottom plate 44 is integrally formed at the lower end of the holding portion 41 of the fixed plate 39. Therefore, the bottom of the power storage element 11 is configured to be isolated from the outside by the bottom plate 44. For example, the bottom plate 44 is formed at a position where the bottom of the power storage element 11 does not come into contact with the power storage element 11 when the power storage element 11 is held by the holding portion 41 . Thereby, even if there is variation in the height of the power storage element 11, the variation can be absorbed by the gap between the bottom of the power storage element 11 and the bottom plate 44.

In the embodiment, fins 45 are integrally formed on the opposite surface of the fixing plate 39 from the holding portion 41 (ie, the outer wall surface). Thereby, the mechanical strength of the fixed plate 39 can be increased. In addition, since the surface area of the outer wall increases by the amount of the fins 45, heat dissipation from the fixed plate 39 can be improved. In the example of FIG. 1, the fin 45 is provided at one location in the center of the fixed plate 39, but the present invention is not limited to this. For example, the fins 45 may be provided at multiple locations on the fixed plate 39. For example, the shape of the fins 45 is not limited to the horizontal direction in FIG. 1, but may extend in the vertical direction.

In the embodiment, the case 47 is fixed to the upper part of the storage member 27 with the fixing plate 39 fixed to the storage member 27. For example, the case 47 is fixed to the upper part of the storage member 27 by tightening the case fixing screw 49 into the case screw hole 33 through the case 47. As a result, the upper part of the power storage element 11 to which the double-sided tape is not attached is covered by the case 47. As a result, the upper part of the power storage element 11 can be isolated from the outside, and the adhesion of dust and the like can be reduced.

In this embodiment, the entire power storage element 11 is isolated from the outside by the concave surface 29, the holding portion 41, the bottom plate 44, and the case 47. Therefore, adhesion of impurities such as dust and suspended particles to the power storage element 11 and the conductive member 100 can be reduced. Therefore, the possibility of corrosion of the power storage element 11 and the conductive member 100 due to impurities is reduced, so that high reliability can be obtained.

For example, the case 47 is made of resin. A plurality of holes 51 are provided on the upper surface of the case 47. Terminals (hereinafter also referred to as "busbar terminals") formed integrally with the busbar, which is the conductive member 100, are made to protrude from the upper surface of the case 47 through these holes 51. A circuit board 53 is provided on the upper surface of the case 47. For example, bus bar terminals are inserted into terminal holes (not shown) provided in the circuit board 53 and soldered. This electrically connects the circuit board 53 and the bus bar terminals. As a result, circuit board 53 can detect the voltage at the electrical connection point of each power storage element 11.

For example, circuit board 53 may have a built-in balance circuit that equalizes the voltage across each power storage element 11 according to the detected voltage. For example, the voltage of each power storage element 11 may be controlled by the balance circuit via a busbar terminal. For example, a plurality of electronic components constituting a voltage detection circuit or a balance circuit may be mounted on the circuit board 53.

In this embodiment, the circuit board 53 is fixed to the case 47 by six circuit board fixing screws 55. The positive terminal 25 and the negative terminal 26 are connected to an external charging/discharging circuit (not shown). For example, if a plurality of power storage devices 1 are used depending on the power specifications, the positive terminal 25 and negative terminal 26 of each power storage device 1 may be connected in series or in parallel with each other.

For example, when using a plurality of power storage devices 1, it is desirable to fix the storage member 27 to a metal pedestal with a large heat capacity so that it is in contact with the base. As a result, the heat of the storage member 27 is quickly transferred to the pedestal, making it possible to dissipate heat even more efficiently. In addition, when the pedestal itself is configured to be water-cooled, even higher heat dissipation performance can be obtained.

In the embodiment, a cooling mechanism 60 is fixed to the lower part of the storage member 27. For example, the cooling mechanism 60 can be fixed to the lower part of the storage member 27 by tightening a cooling plate fixing screw (not shown) into a screw hole (not shown) at the lower part of the storage member 27 via the cooling plate of the cooling mechanism 60. There is. For example, the cooling mechanism 60 has a water channel 61 through which cooling water can flow. Thereby, the heat of the storage member 27 is quickly transferred by water cooling, so that more efficient heat dissipation is possible.

<Configuration of conductive member>
FIG. 5 is an explanatory diagram of welding locations of the conductive member 100 according to the embodiment. FIG. 6 is a diagram showing a portion 111 facing the end electrode 15 in the conductive member 100 according to the embodiment. FIG. 7 is a side view of the conductive member 100 according to the embodiment. FIG. 8 is a diagram showing a portion 120 facing the peripheral electrode 17 in the conductive member 100 according to the embodiment.
The conductive member 100 is connected to the end surface electrode 15 and the peripheral surface electrode 17 by extending from the end surface electrode 15 toward the peripheral surface electrode 17 of the adjacent power storage element 11 . Power storage device 1 has a structure in which heat from end surface electrode 15 is released to storage member 27 via conductive member 100 and peripheral surface electrode 17 .

The plurality of power storage elements 11 have a cylindrical shape and include a first power storage element 11A and a second power storage element 11B that are adjacent to each other. The conductive member 100 electrically connects the first power storage element 11A and the second power storage element 11B. The first power storage element 11A has an end surface electrode 15 at the end in the axial direction. The second power storage element 11B has a circumferential electrode 17 on the outer periphery. The conductive member 100 extends radially outward from the portion 111 facing the end electrode 15 along the first direction V1, and then extends toward the circumferential electrode 17 along the second direction V2 via the bent portion 130. It is extending. Here, the first direction V1 corresponds to a direction orthogonal to the axial direction of the first power storage element 11A. The second direction V2 corresponds to a direction parallel to the axial direction of the first power storage element 11A.

The conductive member 100 has a thick portion 101 in a portion 111 facing the end electrode 15 of the first power storage element 11A, and an end-side thin portion 102 that is thinner than the thick portion 101. The thick portion 101 is provided in the conductive member 100 over a portion 110 extending in the first direction V1 and a portion 120 extending in the second direction V2. The end face side thin wall portion 102 is welded and connected to the end face electrode 15 of the first power storage element 11A (welded portion J1 between the end face side thin wall portion 102 and the end face electrode 15 shown in FIG. 5). For example, the end face side thin wall portion 102 is welded and connected to the end face electrode 15 of the first power storage element 11A by laser welding.

For example, the thickness 101t of the thick portion 101 is set to a thickness of 0.6 mm or more and 3 mm or less. For example, the thickness 102t of the end face side thin wall portion 102 is set to a thickness of 0.3 mm or more and 1 mm or less. In the embodiment, the thickness 101t of the thick portion 101 is 2 mm, and the thickness 102t of the end face side thin portion 102 is 0.6 mm. Note that the thicknesses of the thick portion 101 and the end face side thin portion 102 are not limited to those described above, and can be changed according to required specifications.

Since a conductive member (bus bar) is generally installed in a narrow area, the thick portion of the conductive member is made thin, for example, to about 0.2 mm. When the thick portion is thin in this way, the cross-sectional area (heat transfer area) of the conductive member in the flow of heat becomes small, which increases the electrical resistance and is likely to increase Joule heat.

In contrast, in the embodiment, the thickness 101t of the thick portion 101 of the conductive member 100 is 2 mm, and the cross-sectional area (heat transfer area) of the conductive member 100 in the flow of heat can be increased as much as possible. Therefore, it is possible to achieve both reduction in Joule heat due to reduction in electrical resistance and increase in cooling performance due to increase in heat transfer area.

For example, the ratio S1/S2 between the cross-sectional area S1 of the conductive member 100 and the welding area S2 of the end face side thin wall portion 102 and the end face electrode 15 is set to 0.3 or more and 1.1 or less. Here, the cross-sectional area S1 of the conductive member 100 corresponds to the cross-sectional area (heat transfer area) of the conductive member 100 in the flow of heat. The welding area S2 of the end face side thin wall portion 102 and the end face electrode 15 corresponds to the total area of the end face side thin wall portions 102 at two locations when viewed from the second direction V2. In the portion 110 of the conductive member 100 extending in the first direction V1, the cross-sectional area S1 of the conductive member 100 corresponds to the cross-sectional area of the conductive member 100 when cut along a plane orthogonal to the first direction V1. In an embodiment, the ratio S1/S2 is 0.7. Note that the ratio S1/S2 is not limited to the above, and can be changed according to required specifications.

The thick portion 101 has a uniform thickness in the direction in which the conductive member 100 extends. Here, the thickness 101t of the thick portion 101 corresponds to the thickness of the thick portion 101 in the axial direction of the first power storage element 11A in the portion 111 facing the end electrode 15, and the thickness 120 in the portion facing the peripheral electrode 17. corresponds to the thickness of the thick portion 101 in the radial direction of the second power storage element 11B. The thick portion 101 has a uniform thickness in the first direction V1 at a portion 111 facing the end electrode 15, and a uniform thickness in the second direction V2 at a portion 120 facing the peripheral electrode 17.

The thickness 101t of the thick portion 101 is thicker than the thickness 17t of the peripheral electrode 17. Here, the thickness 17t of the circumferential electrode 17 corresponds to the thickness 17t of the circumferential electrode 17 in the radial direction of the second power storage element 11B. For example, the thickness 17t of the peripheral electrode 17 is set to a thickness of 0.4 mm or more and 1 mm or less. In the embodiment, the thickness 101t of the thick portion 101 is 2 mm, and the thickness 17t of the peripheral electrode 17 is 0.7 mm. Note that the thicknesses of the thick portion 101 and the peripheral electrode 17 are not limited to those described above, and can be changed according to required specifications.

When viewed from the axial direction of the first power storage element 11A, a portion 111 of the thick wall portion 101 that faces the end surface electrode 15 has a larger area than the end surface side thin wall portion 102. Here, the area of the portion 111 of the thick portion 101 that faces the end electrode 15 corresponds to the area of the portion where the thick portion 101 overlaps the end electrode 15 when viewed from the second direction V2. The area of the end face side thin wall portion 102 corresponds to the area of the portion where the end face side thin wall portion 102 overlaps the end face electrode 15 (the area of the two end face side thin wall portions 102) when viewed from the second direction V2.

When viewed from the axial direction of the first power storage element 11A, the portion 111 of the thick portion 101 facing the end electrode 15 is longer than the portion 112 extending radially outward from the portion 111 of the thick portion 101 facing the end electrode 15. It's wide. Here, the width 111w of the portion 111 facing the end electrode 15 in the thick portion 101 corresponds to the maximum length of the thick portion 101 in the direction perpendicular to the first direction V1 when viewed from the second direction V2. The width 112w of the portion 112 extending radially outward from the portion 111 facing the end electrode 15 in the thick portion 101 is the minimum length of the thick portion 101 in the direction perpendicular to the first direction V1 when viewed from the second direction V2. corresponds to

When viewed from the second direction V2, the portion 111 of the thick portion 101 facing the end electrode 15 has a uniform width in the first direction V1, and then gradually increases in width toward the portion 112 extending radially outward. is getting narrower. When viewed from the second direction V2, a portion of the thick portion 101 facing the end electrode 15 that is opposite to the portion 112 extending radially outward is curved in an arc along the outer periphery of the end electrode 15. are doing.

When viewed from the second direction V2, a portion 112 of the thick portion 101 that extends radially outward from the portion 111 facing the end electrode 15 has a uniform width in the first direction V1. When viewed from the second direction V2, a portion (bent portion 130) adjacent to the circumferential electrode 17 of the portion 112 extending radially outward from the portion 111 facing the end electrode 15 in the thick portion 101 is connected to the circumferential electrode 17. It is curved in an arc along the outer circumference.

The end face side thin wall portion 102 extends along the direction in which the conductive member 100 extends. The end face side thin wall portion 102 is formed in a rectangular shape having a longitudinal direction in the first direction V1 when viewed from the second direction V2. Two end face side thin parts 102 are provided at intervals in a direction perpendicular to the first direction V1 when viewed from the second direction V2. The two end face side thin parts 102 have the same shape when viewed from the second direction V2. Note that the shape and number of end face side thin-walled portions 102 are not limited to those described above, and can be changed according to required specifications.

The conductive member 100 has a thick portion 101 in a portion 120 facing the peripheral electrode 17 and a peripheral thin portion 103 thinner than the thick portion 101 . The circumferential thin wall portion 103 is welded to the circumferential electrode 17 (welded portion J2 between the circumferential thin wall portion 103 and the circumferential electrode 17 shown in FIG. 5). For example, the circumferential thin wall portion 103 is welded and connected to the circumferential electrode 17 by laser welding.

For example, the thickness of the circumferential thin wall portion 103 is set to 0.3 mm or more and 1 mm or less. In the embodiment, the thickness 101t of the thick portion 101 is 2 mm, and the thickness of the peripheral thin portion 103 is 0.6 mm. Note that the thicknesses of the thick portion 101 and the peripheral thin portion 103 are not limited to those described above, and can be changed according to required specifications.

The peripheral thin wall portion 103 extends along the direction in which the conductive member 100 extends. The peripheral thin wall portion 103 is formed in a rectangular shape having a longitudinal direction in the second direction V2 when viewed from the first direction V1. Three circumferential thin portions 103 are provided at intervals in a direction perpendicular to the second direction V2 when viewed from the first direction V1. The three circumferential thin portions 103 have the same shape when viewed from the first direction V1. Note that the shape and number of peripheral thin-walled portions 103 are not limited to those described above, and can be changed according to required specifications.

<An example of how to assemble a power storage device>
First, the circumferential electrode 17 of the power storage element 11 and the thin circumferential portion 103 of the conductive member 100 are welded together by laser welding. Next, the power storage elements 11 to which the double-sided tape is attached and to which the conductive member 100 is welded are arranged on the holding portion 41 of the fixing plate 39 . At this time, in order to position each power storage element 11 in the height direction, the electrically conductive members 100 are arranged so as to be in contact with the adjacent end surface electrodes 15 using a jig (not shown).

Next, the end surface electrodes 15 of the power storage elements 11 arranged by the fixing plate 39 and the jig are welded and connected to the thin end surface portion 102 of the conductive member 100.
Next, the protective sheet (not shown) of the double-sided tape is peeled off, and the fixing plate 39 is fixed to the accommodating member 27 with the fixing plate screws 43 so that the power storage element 11 is accommodated in the concave surface 29 of the accommodating member 27. Two rows of power storage elements 11 are fixed to a storage member 27. Thereafter, the conductive member 100 connected to the power storage element 11 at the right end of the rear row in FIG. 1 is welded and connected to the end surface electrode 15 of the power storage element 11 at the right end of the front row. Furthermore, a positive electrode terminal 25 is welded and connected to the end surface electrode 15 at the left end of the rear row.

Next, the case 47 is fixed to the storage member 27 with case fixing screws 49. Thereafter, the circuit board 53 is electrically connected to the bus bar terminals. Further, the circuit board 53 is mechanically connected to the case 47 using the circuit board fixing screws 55.
Note that the above assembly method is an example, and any method other than the above may be used as long as the power storage device 1 can be assembled in an order such as first fixing the power storage element 11 to the storage member 27. I do not care.

For example, the insulating bonding material 35 is not limited to double-sided tape, but may be an adhesive containing thermally conductive filler. According to this configuration, since the adhesive itself has plasticity, the adhesive layer becomes thinner by pushing the power storage element 11 into the concave surface 29, and good thermal conductivity can be obtained. Furthermore, the adhesive can be evenly spread over the gap between the circumferential surface of the power storage element 11 and the concave surface 29, and firm holding is also possible.

For example, an insulating portion such as an insulating tube may be provided on the circumferential surface of the circumferential electrode 17 of the power storage element 11 other than the portion to which the conductive member 100 is connected. As a result, the circumferential surface of the power storage element 11 is insulated by the insulating tube, so the bonding material 35 with the storage member 27 does not need to be insulating. Therefore, for example, when using a double-sided tape, a metal conductive filler can be contained in the adhesive part as a heat conductive filler, and the heat conductivity is improved.

<Analysis results>
In a power storage device (for example, a capacitor assembly), the temperature inside the power storage element is an important factor in determining the allowable current. Therefore, the inventor conducted a thermal analysis for each capacitor submodule. As a result of extensive studies, the inventor has determined that a conductive member (bus bar) that electrically connects two adjacent power storage elements accounts for a certain percentage of the path through which heat generated inside the power storage element escapes to the side surface of the power storage element. I found out that

Therefore, in the embodiment, the thickness 101t of the thick portion 101 of the conductive member 100 is increased to reduce Joule heat by lowering electrical resistance and increasing the amount of heat dissipated to the adjacent power storage element 11 by lowering the thermal resistance. did. However, if the thickness of the conductive member 100 is uniformly increased, welding with the power storage element 11 becomes difficult, so welding is made possible by locally reducing the thickness of only the welding portions J1 and J2.

FIG. 9 is a diagram for explaining a structure in which heat from the end electrode 15 is released to the storage member 27 via the conductive member 100 and the peripheral electrode 17.
Power storage device 1 has a structure in which heat inside power storage element 11 escapes to water channel 61 of cooling mechanism 60 via end surface electrode 15 , conductive member 100 , peripheral surface electrode 17 , and storage member 27 . Specifically, the heat generated inside the first power storage element 11A among the first power storage element 11A and the second power storage element 11B that are adjacent to each other is transferred to the end surface electrode 15 of the first power storage element 11A, the conductive member 100, and the first power storage element 11A. The heat is transmitted to the circumferential electrode 17 of the second power storage element 11B next to the power storage element 11A, and then to the storage member 27, and then escapes to the water channel 61 of the cooling mechanism 60 (an example of heat flow).

In the example of FIG. 9, five temperature measurement points P1 to P5 are set in order to measure the temperature in the flow of heat. The five temperature measurement points P1 to P5 are a first temperature measurement point P1 for measuring the temperature of the upper part of the first power storage element 11A (element upper part), and a first temperature measurement point P1 for measuring the temperature of the conductive member 100 (bus bar). 2 temperature measurement point P2, a third temperature measurement point P3 for measuring the temperature of the peripheral surface electrode 17 (side surface of the adjacent cell) of the second power storage element 11B, and a third temperature measurement point P3 for measuring the temperature of the storage member 27 (heat sink). It includes a fourth temperature measurement point P4 and a fifth temperature measurement point P5 for measuring the temperature of the cooling mechanism 60 (cooling plate).

FIG. 10 is a diagram showing the cooling effect of the conductive member 100 of the example together with a comparative example. Here, the conductive member 100 of the present embodiment (the conductive member 100 in which the thickness 101t of the thick portion 101 is 2.0 mm) is taken as an example, and the conductive member with a uniform thickness (the conductive member in which the thickness of the conductive member is 0.6 mm) is used as an example. A conductive member with no thin wall portion) is used as a comparative example. Note that the examples are specific examples to which the present invention is applied, and do not limit the present invention.

As shown in FIG. 10, it was confirmed that in the process of heat flowing from the top of the element toward the cooling plate, the temperature gradient of the conductive member 100 of the example was improved by increasing the thickness of the thick portion 101. In particular, it was confirmed that the temperature gradient in the example was gentler than in the comparative example between the top of the element and the side surface of the adjacent cell. As a result, it was found that the example had a higher cooling capacity than the comparative example, and that the temperature was easily transmitted.

<Effect>
As described above, the power storage device 1 of the present embodiment has a cylindrical shape, has thermal conductivity, and has a first power storage element 11A and a second power storage element 11B that are adjacent to each other. It includes a storage member 27 that stores the second power storage element 11B, and a conductive member 100 that electrically connects the first power storage element 11A and the second power storage element 11B. The first power storage element 11A has an end surface electrode 15 at the end in the axial direction. The second power storage element 11B has a circumferential electrode 17 on the outer periphery. The conductive member 100 is connected to the end surface electrode 15 and the peripheral surface electrode 17 by extending from the end surface electrode 15 toward the peripheral surface electrode 17 of the adjacent power storage element 11 . The conductive member 100 has a thick portion 101 in a portion 111 facing the end electrode 15 and an end thin portion 102 thinner than the thick portion 101 . The end face side thin wall portion 102 is connected to the end face electrode 15 by welding. Power storage device 1 has a structure in which heat from end surface electrode 15 is released to storage member 27 via conductive member 100 and peripheral surface electrode 17 .
According to this configuration, the end face side thin part 102, which is thinner than the thick part 101 of the conductive member 100, is welded and connected to the end face electrode 15, thereby reducing the amount of heat input to the power storage element 11 during welding. Can be done. Therefore, thermal damage to power storage element 11 during welding can be suppressed. In addition, by having a structure in which the heat of the end electrode 15 is released to the storage member 27 via the conductive member 100 and the peripheral electrode 17, the cooling path for the power storage element 11 is not only radial but also axial. Heat can also be released from the directional ends. That is, by strengthening the cooling path from the end surface electrode 15 at the axial end of the power storage element 11, the cooling performance can be improved. Therefore, cooling performance can be improved while suppressing thermal damage to power storage element 11 when welding conductive member 100.

In this embodiment, the thick portion 101 has a uniform thickness in the directions V1 and V2 in which the conductive member 100 extends.
According to this configuration, when heat flows in the directions V1 and V2 in which the conductive member 100 extends, the thick portion 101 has a uniform cross-sectional area, so that the heat can be smoothly dissipated.

In this embodiment, the thickness 101t of the thick portion 101 is thicker than the thickness 17t of the peripheral electrode 17.
According to this configuration, the cross-sectional area (heat transfer area) of the conductive member 100 in the flow of heat can be increased compared to the case where the thickness 101t of the thick portion 101 is less than or equal to the thickness 17t of the peripheral electrode 17. . Therefore, it is possible to achieve both reduction in Joule heat due to reduction in electrical resistance and increase in cooling performance due to increase in heat transfer area.

In this embodiment, when viewed from the axial direction of the first power storage element 11A, a portion 111 of the thick portion 101 that faces the end surface electrode 15 has a larger area than the end surface side thin portion 102.
According to this configuration, the contact area between the end electrode 15 and the portion 111 of the thick portion 101 that faces the end electrode 15 can be increased. Therefore, the heat transfer performance can be further improved by contacting not only the end face side thin wall part 102 but also the thick wall part 101 and the end face electrode 15 as connection parts of the conductive member 100.

In this embodiment, when viewed from the axial direction of the first power storage element 11A, the portion 111 of the thick wall portion 101 facing the end surface electrode 15 is radially outward from the portion 111 of the thick wall portion 101 facing the end surface electrode 15. It is wider than the extending portion 112.
According to this configuration, even if the end face side thin wall portion 102 is present in the portion 111 facing the end face electrode 15 in the conductive member 100, the heat transfer area is sufficiently increased by the portion 111 facing the end face electrode 15 in the thick wall portion 101. can be done. Therefore, it is possible to simultaneously reduce Joule heat by reducing electrical resistance and increase cooling performance by increasing heat transfer area.

In this embodiment, the end face thin portion 102 extends along the direction V1 in which the conductive member 100 extends.
For example, in a configuration in which the end face side thin wall portion 102 extends in a direction intersecting the direction V1 in which the conductive member 100 extends, when heat flows in the direction V1 in which the conductive member 100 extends, the end face side thin wall portion 102 becomes an impediment to the flow of heat. There is a possibility that it will become. On the other hand, according to this configuration, the end face side thin wall portion 102 extends along the direction V1 in which the conductive member 100 extends, so that when heat flows in the direction V1 in which the conductive member 100 extends, the end face side thin part 102 The thin side portion 102 does not get in the way. Therefore, heat can be smoothly released.

In this embodiment, the conductive member 100 has a thick portion 101 in a portion 120 facing the circumferential electrode 17 and a circumferential thin portion 103 thinner than the thick portion 101 . The peripheral thin wall portion 103 is connected to the peripheral electrode 17 by welding.
According to this configuration, the circumferential thin wall portion 103, which is thinner than the thick wall portion 101 of the conductive member 100, is welded and connected to the circumferential electrode 17, thereby reducing the amount of heat input to the power storage element 11 during welding. can be reduced. Therefore, thermal damage to power storage element 11 during welding can be suppressed. In addition, the conductive member 100 has the thick portion 101 not only in the portion 111 facing the end electrode 15 but also in the portion 120 facing the circumferential electrode 17, so that the end electrode 15 at the axial end of the power storage element 11 It is possible to further strengthen the cooling path from the ground, and the cooling performance can be further improved. Therefore, cooling performance can be further improved while suppressing thermal damage to power storage element 11 when welding conductive member 100.

In this embodiment, the peripheral thin wall portion 103 extends along the direction V2 in which the conductive member 100 extends.
For example, in a configuration in which the circumferential thin wall portion 103 extends in a direction intersecting the direction V2 in which the conductive member 100 extends, when heat flows in the direction V2 in which the conductive member 100 extends, the circumferential thin wall portion 103 extends in the direction V2 in which the conductive member 100 extends. may become a hindrance. On the other hand, according to the present configuration, the circumferential thin wall portion 103 extends along the direction V2 in which the conductive member 100 extends, so that when heat flows in the direction V2 in which the conductive member 100 extends, The peripheral thin wall portion 103 does not get in the way. Therefore, heat can be smoothly released.

In this embodiment, the conductive member 100 extends radially outward from the portion 111 facing the end electrode 15 and then extends toward the circumferential electrode 17 via the bent portion 130 .
According to this configuration, even if there is a positional shift when welding and connecting the conductive member 100 to the end surface electrode 15 of the adjacent power storage element 11, it can be absorbed by the bent portion 130. In addition, even if vibrations are applied to the entire power storage device 1 after assembly from the outside, the stress applied to the welded connection portion between the conductive member 100 and the end electrode 15 can be alleviated by the bent portion 130. Therefore, the possibility that the welded portion between the conductive member 100 and the end electrode 15 comes off due to vibration can be reduced, and good vibration resistance can be obtained.

<Other embodiments>
In the embodiments described above, the thick portion has been described as having a uniform thickness in the direction in which the conductive member extends, but the thick portion is not limited to this. For example, the thick portion may not have a uniform thickness in the direction in which the conductive member extends. For example, the thick portion includes a first thickness portion having a first thickness in the direction in which the conductive member extends, and a second thickness portion having a second thickness that is thicker than the first thickness portion. It's okay. For example, the thickness of the thick portion in the direction in which the conductive member extends can be changed depending on required specifications.

In the embodiment described above, the thickness of the thick portion is explained by giving an example where it is thicker than the thickness of the peripheral electrode, but the thickness is not limited to this. For example, the thickness of the thick portion may be less than or equal to the thickness of the peripheral electrode. For example, the relationship between the thickness of the thick portion and the peripheral electrode can be changed depending on required specifications.

In the above-described embodiment, the area of the thick portion facing the end electrode is larger than the thin wall portion of the end surface when viewed from the axial direction of the first energy storage element, but the present invention is not limited to this. . For example, when viewed from the axial direction of the first power storage element, the area of the thick portion facing the end surface electrode may be smaller than that of the end surface side thin wall portion. For example, the relationship between the areas of the thick portion facing the end electrode and the end thin portion can be changed depending on the required specifications.

In the embodiment described above, when viewed from the axial direction of the first energy storage element, the portion of the thick wall portion facing the end surface electrode is wider than the portion of the thick wall portion that extends radially outward from the portion facing the end surface electrode. Although the explanation has been given using a wide range of examples, the invention is not limited to this. For example, when viewed from the axial direction of the first energy storage element, the portion of the thick wall portion that faces the end electrode may be narrower than the portion of the thick wall portion that extends radially outward from the portion that faces the end electrode. . For example, when viewed from the axial direction of the first energy storage element, the portion of the thick wall portion that faces the end electrode may have a width equal to that of the portion of the thick wall portion that extends radially outward from the portion that faces the end electrode. . For example, the relationship between the widths of the portion of the thick portion that faces the end electrode and the portion that extends outward in the radial direction can be changed depending on the required specifications.

In the above-described embodiment, the end face side thin wall portion has been described with reference to an example extending along the direction in which the conductive member extends, but the present invention is not limited to this. For example, the end face side thin portion may extend in a direction intersecting the direction in which the conductive member extends. For example, the manner in which the thin end face portion extends can be changed depending on required specifications.

In the above-described embodiment, the conductive member has been described with reference to an example in which the portion facing the circumferential electrode has a thick portion and a thin portion on the circumferential side that is thinner than the thick portion. Not exclusively. For example, the conductive member may have only a circumferential thin wall portion in a portion facing the circumferential electrode. For example, the conductive member may have only a thick portion in a portion facing the peripheral electrode. In this case, the thick portion may be connected to the peripheral electrode by welding. For example, the configuration of the portion of the conductive member that faces the peripheral electrode can be changed depending on required specifications.

In the above-described embodiments, the thin wall portion on the circumferential surface side has been described using an example in which the thin wall portion extends along the direction in which the conductive member extends, but the present invention is not limited to this. For example, the peripheral thin wall portion may extend in a direction intersecting the direction in which the conductive member extends. For example, the manner in which the peripheral thin wall portion extends can be changed depending on required specifications.

In the above-described embodiment, the conductive member extends radially outward from the portion facing the end electrode, and then extends toward the circumferential electrode via the bent portion. However, the present invention is not limited to this. do not have. For example, the conductive member may extend radially outward from a portion facing the end electrode, and then extend toward the circumferential electrode without passing through the bent portion. For example, the conductive member may extend radially outward from a portion facing the end electrode, and then extend toward the circumferential electrode via the curved portion. For example, the manner in which the conductive member extends can be changed depending on required specifications.

In the embodiment described above, an example has been described in which the conductive member is welded and connected to the electrode of the power storage element by laser welding, but the present invention is not limited to this. For example, the conductive member may be welded and connected to the electrode of the power storage element by arc welding, gas welding, or the like. For example, the manner in which the conductive member is welded can be changed depending on required specifications.

Although the above-described embodiment has been described using an example in which the electricity storage element is an electric double layer capacitor, the present invention is not limited to this. For example, the power storage element may be another capacitor such as an electrochemical capacitor or a secondary battery. For example, the aspect of the power storage element can be changed according to required specifications.

(Additional note 1)
A first power storage element and a second power storage element that have a cylindrical shape and are adjacent to each other;
a storage member that has thermal conductivity and stores the first power storage element and the second power storage element;
a conductive member that electrically connects the first power storage element and the second power storage element,
The first power storage element has an end electrode at an axial end,
The second electricity storage element has a peripheral electrode on the outer peripheral part,
The conductive member is connected to the end electrode and the peripheral electrode by extending from the end electrode toward the peripheral electrode,
The conductive member has a thick portion in a portion facing the end electrode, and an end side thin portion that is thinner than the thick portion,
The end surface side thin wall portion is welded and connected to the end surface electrode,
The structure is such that heat from the end electrode is released to the storage member through the conductive member and the peripheral electrode.
Power storage device.

(Additional note 2)
The thick portion has a uniform thickness in the direction in which the conductive member extends.
The power storage device according to Supplementary Note 1.

(Additional note 3)
The thickness of the thick portion is greater than the thickness of the peripheral electrode.
The power storage device according to Supplementary Note 1 or 2.

(Additional note 4)
When viewed from the axial direction of the first power storage element, a portion of the thick wall portion facing the end surface electrode has a larger area than the end surface side thin wall portion.
The power storage device according to any one of Supplementary Notes 1 to 3.

(Appendix 5)
When viewed from the axial direction of the first power storage element, a portion of the thick wall portion that faces the end electrode is wider than a portion of the thick wall portion that extends radially outward from the portion that faces the end electrode. ,
The power storage device according to any one of Supplementary Notes 1 to 4.

(Appendix 6)
The end face side thin wall portion extends along the direction in which the conductive member extends.
The power storage device according to any one of Supplementary Notes 1 to 5.

(Appendix 7)
The conductive member has the thick portion and a peripheral thin portion thinner than the thick portion in a portion facing the peripheral electrode,
The circumferential thin wall portion is welded to the circumferential electrode,
The power storage device according to any one of Supplementary Notes 1 to 6.

(Appendix 8)
The peripheral thin wall portion extends along the direction in which the conductive member extends.
The power storage device according to appendix 7.

(Appendix 9)
The conductive member extends radially outward from a portion facing the end electrode, and then extends toward the peripheral electrode via a bent portion.
The power storage device according to any one of Supplementary Notes 1 to 8.

Although the embodiments of the present invention have been described above, the present invention is not limited to these, and additions, omissions, substitutions, and other changes to the configuration are possible without departing from the spirit of the present invention. It is also possible to combine the embodiments described above as appropriate.

DESCRIPTION OF SYMBOLS 1... Power storage device, 11A... 1st power storage element, 11B... 2nd power storage element, 15... End surface electrode, 17... Circumferential surface electrode, 17t... Thickness of circumferential surface electrode, 27... Storage member, 100... Conductive member, 101... Thick part, 101t... Thickness of the thick part, 102... Thin wall part on the end surface side, 103... Thin wall part on the peripheral surface side, 111... Portion facing the end electrode in the thick part, 111w... Opposing the end electrode in the thick part. 112...A portion extending radially outward in the thick wall portion, 112w...Width of a portion extending radially outward in the thick wall portion, 130...Bending portion, V1...First direction (direction in which the conductive member extends) , V2...second direction (direction in which the conductive member extends)

Claims (9)

A first power storage element and a second power storage element that have a cylindrical shape and are adjacent to each other;
a storage member that has thermal conductivity and stores the first power storage element and the second power storage element;
a conductive member that electrically connects the first power storage element and the second power storage element,
The first power storage element has an end electrode at an axial end,
The second electricity storage element has a peripheral electrode on the outer peripheral part,
The conductive member is connected to the end electrode and the peripheral electrode by extending from the end electrode toward the peripheral electrode,
The conductive member has a thick portion in a portion facing the end electrode, and an end side thin portion that is thinner than the thick portion,
The end surface side thin wall portion is welded and connected to the end surface electrode,
The structure is such that heat from the end electrode is released to the storage member through the conductive member and the peripheral electrode.
Power storage device. The thick portion has a uniform thickness in the direction in which the conductive member extends.
The power storage device according to claim 1. The thickness of the thick portion is greater than the thickness of the peripheral electrode.
The power storage device according to claim 1 or 2. When viewed from the axial direction of the first power storage element, a portion of the thick wall portion facing the end surface electrode has a larger area than the end surface side thin wall portion.
The power storage device according to claim 1 or 2. When viewed from the axial direction of the first power storage element, a portion of the thick wall portion that faces the end electrode is wider than a portion of the thick wall portion that extends radially outward from the portion that faces the end electrode. ,
The power storage device according to claim 1 or 2. The end face side thin wall portion extends along the direction in which the conductive member extends.
The power storage device according to claim 1 or 2. The conductive member has the thick portion and a peripheral thin portion thinner than the thick portion in a portion facing the peripheral electrode,
The circumferential thin wall portion is welded to the circumferential electrode,
The power storage device according to claim 1 or 2. The peripheral thin wall portion extends along the direction in which the conductive member extends.
The power storage device according to claim 7. The conductive member extends radially outward from a portion facing the end electrode, and then extends toward the peripheral electrode via a bent portion.
The power storage device according to claim 1 or 2.

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