JP2022182106A - power storage device - Google Patents

Abstract

To provide a power storage device having a weld part that is a part where two resin-made members are welded and can improve reliability.SOLUTION: A power storage device 1 includes an outer package body 110 and a lid body 120 which are formed of a resin. The outer package body 110 and the lid body 120 are joined to each other in a weld part 140 extending in a predetermined direction. The weld part 140 is formed at a position that is not exposed to the outer surfaces of the outer package body 110 and the lid body 120 in the joined state. At least one of the outer package body 110 and the lid body 120 has a gas storage part 118 which has such a shape as to be recessed in a direction apart from the other and extends in the predetermined direction along the weld part 140.SELECTED DRAWING: Figure 4B

Description

The present invention relates to a power storage device including two members made of resin.

Patent Literature 1 discloses a battery pack including a battery storage case. This battery storage case has a first case and a second case. The first case has welding projections and the second case has welding grooves. The welding projection and the welding groove are ultrasonically welded while the welding projection is inserted into the welding groove.

WO2011/096159

Like the above conventional battery pack, in a power storage device provided with a resin battery storage case (exterior body), ultrasonic welding or heat welding is used to join two members such as a main body and a lid constituting the exterior body. , or bonding using an adhesive. In addition to ultrasonic welding and thermal welding, there is laser welding using laser light (also referred to as laser resin welding) as a technique for welding resins together. Laser welding is a method of joining (welding) two resin-made members by melting the resin with the heat generated by the resin that has absorbed the laser beam. Laser welding has advantages such as being able to perform efficient and highly accurate joining while suppressing the spread of thermal effects. In addition, since laser welding does not give mechanical vibration to the objects to be joined, for example, there is no problem caused by vibration during the joining work in the exterior body and the battery (electrical storage element) and circuit board housed in it. It also has the advantage of not occurring.

However, when the resin is melted by the heat of the laser beam, flame retardants and other substances contained in the resin evaporate, generating gas. entrapment, which can create voids in the weld. If voids occur in the welded portion, problems such as a decrease in bonding strength occur. Therefore, suppressing the generation of voids in the welded portion is an important issue from the viewpoint of improving the reliability of the welded portion.

The present invention has been made by the inventors of the present invention by newly paying attention to the above problems, and is a welded portion, which is a portion where two members made of resin are welded, and has improved reliability. An object of the present invention is to provide a power storage device having

A power storage device according to an aspect of the present invention includes a first member and a second member, each of which is made of resin. The welded portion is formed at a position not exposed to the outer surfaces of the first member and the second member in a joined state, and at least one of the first member and the second member is and a gas storage portion recessed in a direction away from the other and extending in the predetermined direction along the welded portion.

According to this configuration, when the first member and the second member are joined by, for example, laser welding, the gas generated by this welding is contained in the gas containing portion. This suppresses the generation of voids in the welded portion. Since the gas containing portion extends along the welded portion extending in a predetermined direction, the generation of voids in the welded portion is suppressed over a wide range. As described above, the power storage device according to this aspect is a power storage device having a welded portion, which is a portion where two resin-made members are welded together, and has improved reliability.

One of the first member and the second member has a convex portion extending in the predetermined direction, and the other of the first member and the second member has a concave portion extending in the predetermined direction. and at the welding portion, at least part of the projection and at least part of the recess are joined by welding in a state in which the projection is engaged or fitted into the recess. good.

According to this configuration, the first member and the second member, which are both made of resin, are joined together in a state in which the concave portion and the convex portion are engaged or fitted. Therefore, for example, the mechanical strength of the joint portion (including the welded portion) between the first member and the second member is improved.

The gas containing portion may be formed by a gap between the convex portion and the concave portion.

According to this configuration, for example, the combination of the concave portion and the convex portion smaller in size than the internal space of the concave portion can provide the gas storage portion extending along the welded portion. In other words, the gas storage portion can be formed along (continuously) the welded portion with a relatively simple configuration without providing a (dedicated) recessed shape only for the gas storage portion in the first member or the second member. can be provided.

The gas containing portion may be formed by a recess provided in a part of the convex portion.

According to this configuration, for example, the gas containing portion extending along the welded portion can be provided in a state in which the concave portion and the convex portion are in close contact with each other over a relatively large area. Therefore, for example, it is possible to relatively increase the volume of the welded portion while suppressing the generation of voids in the welded portion, and to mechanically bond the convex portion and the concave portion more strongly.

Furthermore, one of the first member and the second member may be formed with a vent hole extending from the gas storage portion to the outer surface of the one.

According to this configuration, the gas that is generated during welding and once stored in the gas storage portion can be released to the outside of the first member and the second member through the ventilation hole. Therefore, even if the volume of the gas storage portion is small relative to the amount of generated gas, the possibility of the internal pressure of the gas storage portion increasing excessively is reduced. This contributes to improving the reliability of the welded portion.

Each of the first member and the second member may be a member forming part of an exterior body of the power storage device.

According to this configuration, for example, a welded portion with improved reliability is formed at a joint portion between the first member and the second member, which are the main body of the exterior body and the lid body that closes the opening of the main body. Therefore, leakage of gas from the welded portion and entry of water from the welded portion into the interior of the exterior body are suppressed when the valve of the storage element is opened. As a result, for example, the safety of the power storage device can be improved, or the life of the product can be extended.

According to the present invention, it is possible to provide a power storage device having a welded portion, which is a portion where two members made of resin are welded together, and which has improved reliability.

1 is a perspective view showing an appearance of a power storage device according to an embodiment; FIG. 1 is an exploded perspective view of a power storage device according to an embodiment; FIG. FIG. 4 is a perspective cross-sectional view showing a structural relationship between an exterior body and a lid according to the embodiment; FIG. 4 is a cross-sectional view showing a state in which an exterior main body and a lid according to the embodiment are combined; FIG. 4 is a cross-sectional view showing a state in which an exterior main body and a lid are welded together according to the embodiment; FIG. 11 is a cross-sectional view showing a state in which an exterior main body and a lid are combined according to Modification 1 of the embodiment; FIG. 10 is a cross-sectional view showing a state in which an exterior body and a lid are welded together according to Modification 1 of the embodiment; FIG. 11 is a cross-sectional view showing a state in which an exterior main body and a lid are combined according to Modification 2 of the embodiment; FIG. 11 is a cross-sectional view showing a state in which an exterior main body and a lid are welded together according to Modification 2 of the embodiment; FIG. 11 is a cross-sectional view showing a state in which an exterior main body and a lid are combined according to Modification 3 of the embodiment; FIG. 11 is a cross-sectional view showing a state in which an exterior main body and a lid are welded together according to Modification 3 of the embodiment;

Hereinafter, power storage devices according to embodiments of the present invention (including modifications thereof) will be described with reference to the drawings. It should be noted that the embodiments described below are all comprehensive or specific examples. Numerical values, shapes, materials, constituent elements, arrangement positions and connection forms of constituent elements, manufacturing processes, order of manufacturing processes, and the like shown in the following embodiments are examples, and are not intended to limit the present invention. Also, in each drawing, dimensions and the like are not strictly illustrated. Furthermore, in each figure, the same reference numerals are given to the same or similar components.

In the following description and drawings, the longitudinal direction of the exterior body of the power storage device or the facing direction of the short sides of the power storage element is defined as the X-axis direction. The lateral direction of the exterior body of the power storage device or the direction in which a plurality of power storage elements are arranged is defined as the Y-axis direction. The direction in which the main body of the exterior body and the lid body of the power storage device are aligned, or the vertical direction, is defined as the Z-axis direction. These X-axis direction, Y-axis direction, and Z-axis direction are directions that cross each other (perpendicularly in this embodiment). Although the Z-axis direction may not be the vertical direction depending on the mode of use, the Z-axis direction will be described below for convenience of explanation.

Further, in the following description, for example, the positive direction of the X-axis indicates the direction of the arrow of the X-axis, and the negative direction of the X-axis indicates the opposite direction to the positive direction of the X-axis. The same applies to the Y-axis direction and the Z-axis direction. Further, simply referring to the "X-axis direction" means either or both directions parallel to the X-axis. The same applies to terms relating to the Y-axis and Z-axis.

Furthermore, expressions indicating relative directions or orientations such as parallel and orthogonal include cases where they are not strictly the directions or orientations. For example, two directions are orthogonal, not only means that the two directions are completely orthogonal, but also substantially orthogonal, that is, for example, a difference of about several percent It is also meant to include

(Embodiment)
[1-1. General description of power storage device]
First, a general description of a power storage device 1 according to an embodiment will be given with reference to FIGS. 1 and 2. FIG. FIG. 1 is a perspective view showing the appearance of a power storage device 1 according to an embodiment. FIG. 2 is an exploded perspective view of the power storage device 1 according to the embodiment. FIG. 2 illustrates a state in which the lid 120 of the exterior body 10 is separated from the exterior body main body 110 to expose a plurality of power storage elements 20 (power storage element units 24).

The power storage device 1 is a device that can charge electricity from the outside and discharge electricity to the outside, and has a substantially rectangular parallelepiped shape in the present embodiment. The power storage device 1 is, for example, a battery module (assembled battery) used for power storage or power supply. Specifically, the power storage device 1 is, for example, an automobile, a motorcycle, a watercraft, a ship, a snowmobile, an agricultural machine, a construction machine, or a rolling stock for an electric railway. It is used as a battery etc. Examples of such vehicles include electric vehicles (EV), hybrid electric vehicles (HEV), plug-in hybrid electric vehicles (PHEV), and fossil fuel (gasoline, light oil, liquefied natural gas, etc.) gasoline vehicles. Examples of railway vehicles for the electric railway include electric trains, monorails, linear motor cars, and hybrid trains having both diesel engines and electric motors. The power storage device 1 can also be used as a stationary battery or the like for home or business use.

As shown in FIGS. 1 and 2 , the power storage device 1 includes a power storage element 20 and an exterior body 10 that accommodates the power storage element 20 . In the present embodiment, exterior body 10 accommodates four power storage elements 20 . Note that the number of power storage elements 20 included in power storage device 1 is not limited to four. The power storage device 1 may include one or more power storage elements 20 . In this embodiment, one storage element unit 24 is configured by four storage elements 20 arranged in the Y-axis direction. The storage element unit 24 may have a spacer, an insulating film, and the like (not shown).

The exterior body 10 has an exterior body body 110 that accommodates the power storage element unit 24 and a lid body 120 that closes an opening of the exterior body body 110 (body opening 111). In the present embodiment, the exterior body main body 110 is an example of the first member, and the lid body 120 is an example of the second member. Bus bars electrically connected to the plurality of storage elements 20, a bus bar plate that holds the bus bars, a control circuit, and the like are arranged above the storage element units 24 inside the exterior body 10. Illustration and description of members are omitted.

The exterior body 10 is a substantially rectangular parallelepiped (box-shaped) container (module case) that constitutes the outer shell of the power storage device 1 . In other words, the exterior body 10 is a member that fixes the power storage element unit 24 and the like to predetermined positions and protects them from impacts and the like. The exterior body 110 included in the exterior body 10 is a bottomed rectangular cylindrical housing in which a body opening 111 for accommodating the power storage element unit 24 is formed. The lid 120 is a rectangular member that closes the body opening 111 of the exterior body 110 . The exterior body main body 110 is an example of a first member, and the lid body 120 is an example of a second member. In the present embodiment, the exterior body main body 110 and the lid body 120 are each made of a thermoplastic resin, and the exterior body body 110 and the lid body 120 are joined by laser welding. The details of the joint portion between the exterior body main body 110 and the lid body 120 will be described later with reference to FIGS. 3 to 4B.

The lid 120 has a positive electrode side external terminal 91 and a negative electrode side external terminal 92 . The external terminals 91 and 92 are electrically connected to a plurality of power storage elements 20, and the power storage device 1 charges electricity from the outside and discharges electricity to the outside through the external terminals 91 and 92. do. The external terminals 91 and 92 are made of a conductive member made of metal such as aluminum or aluminum alloy.

The storage element 20 is a secondary battery (single battery) capable of charging and discharging electricity, and more specifically, a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery. . The storage element 20 has a flattened rectangular parallelepiped (rectangular) shape, and in the present embodiment, as described above, four storage elements 20 are arranged in the Y-axis direction.

Note that the storage element 20 is not limited to a non-aqueous electrolyte secondary battery, and may be a secondary battery other than a non-aqueous electrolyte secondary battery, or may be a capacitor. The power storage element 20 may be a primary battery that can use stored electricity without being charged by the user, instead of a secondary battery. The storage element 20 may be a battery using a solid electrolyte. The storage element 20 may be a pouch-type storage element. Moreover, the shape of the electric storage element 20 is not limited to the rectangular shape described above, and may be other shapes such as a polygonal columnar shape, a cylindrical shape, an elliptical columnar shape, and an oval columnar shape.

In this embodiment, the storage element 20 includes a container 21 made of metal. The container 21 is a rectangular case having a pair of long sides 21a facing each other and a pair of short sides 21b facing each other. The container 21 accommodates an electrode assembly, a current collector, an electrolytic solution, and the like. In the present embodiment, each of the plurality of power storage elements 20 is arranged in a row in the Y-axis direction with the long side 21a facing the Y-axis direction (the short side 21b is parallel to the Y-axis direction).

A cover plate 21 c of the container 21 is provided with metal electrode terminals 22 (a positive electrode terminal and a negative electrode terminal) electrically connected to the electrode body inside the container 21 . The electrode terminal 22 is arranged to protrude upward (Z-axis positive direction) from the cover plate 21c of the container 21 . A gas discharge valve 23 is further provided on the cover plate 21c of the container 21 . The gas discharge valve 23 can discharge the gas inside the container 21 to the outside by opening (valve opening) when the internal pressure of the container 21 rises excessively. In the present embodiment, as shown in FIG. 2, each of the plurality of power storage elements 20 is arranged with the gas exhaust valve 23 directed in the positive direction of the Z axis.

In power storage device 1 having such a basic configuration, body opening 111 of exterior body body 110 is sealed with lid body 120 . Specifically, when the electricity storage element 20 opens and the gas spouts out, for example, in order to ensure the safety of the user of the electricity storage element 20, a predetermined amount of gas is discharged from an exhaust port (not shown) provided in the exterior body 10. It is necessary to guide the gas to the place of However, if there is a gap between the joint between the exterior main body 110 and the lid 120, or if the gap is caused by gas pressure, the gas will leak from an unexpected position. can cause unsafe events. Furthermore, the power storage device 1 may be used in a situation where it is exposed to wind and rain, or may be submerged due to a natural disaster or the like. Therefore, in some cases, high airtightness or watertightness is required for the joint portion between the exterior body main body 110 and the lid body 120 .

Accordingly, the joint portion between exterior body main body 110 and lid body 120 is an important portion from the viewpoint of reliability of power storage device 1 . Therefore, in the present embodiment, the exterior body main body 110 and the lid body 120 are joined by welding. More specifically, the exterior body main body 110 and the lid body 120 are welded by laser welding using a laser beam. As a result, it is possible to form the joint portion between the exterior body main body 110 and the lid body 120 efficiently and with high precision. Details of the joint portion between the exterior body main body 110 and the lid body 120 according to the present embodiment will be described below with reference to FIGS. 3 to 4B.

[1-2. Regarding the junction between the main body of the exterior body and the lid body]
FIG. 3 is a perspective cross-sectional view showing the structural relationship between the exterior body main body 110 and the lid body 120 according to the embodiment. FIG. 3 shows a cross section of the exterior main body 110 and the lid 120 on the YZ plane passing through line III-III in FIG. They are shown separated from each other. FIG. 4A is a cross-sectional view showing a state in which the exterior body main body 110 and the lid body 120 according to the embodiment are combined, and FIG. FIG. 10 is a cross-sectional view showing a folded state; The positions of the cross sections in FIGS. 4A and 4B correspond to the positions of the cross sections in FIG.

As shown in FIG. 2 and FIGS. 3 to 4B, the lid 120 is attached to the exterior body 110 from the opening direction (Z-axis plus direction) of the body opening 111 of the exterior body 110. It is a member that can be used. The exterior body main body 110 has a first wall portion 115 provided on the periphery of the main body opening portion 111 . The lid 120 has a second wall portion 125 joined to the first wall portion 115, as shown in FIGS. 3-4B. As shown in FIGS. 4A and 4B, the second wall portion 125 of the lid body 120 faces the first wall portion 115 on the outside of the first wall portion 115 of the exterior main body 110 (the exterior side of the exterior body 10). It is placed in the position where In this state, the second wall portion 125 is irradiated with the laser light L, thereby forming the welded portion 140 where the first wall portion 115 and the second wall portion 125 are welded.

Specifically, at least a portion of the lid 120 irradiated with the laser beam L is made of a resin that allows the laser beam L to pass therethrough. is formed of a resin that absorbs the laser beam L. Resins (transmission side resins) that can transmit the laser light L and can be welded include polypropylene (PP), polyethylene (PE), polystyrene (PS), polyphenylene sulfide resin (PPS), polyphenylene ether (PPE (modified (including PPE)), polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polyamide (PA), and thermoplastic resins such as ABS, which are transparent or have a low colorant content. be done. The resin that absorbs the laser light L (absorbing side resin) is a thermoplastic resin such as PE or PP described above, and contains a coloring material that absorbs the wavelength of the laser light L and efficiently converts it into heat. Examples include resins that

For example, the entire lid body 120 is formed of an uncolored (transparent, translucent, white, or the like) thermoplastic resin having a high laser transmittance, which is a transmission-side resin. In addition, the entire exterior body main body 110 is formed of a black or gray thermoplastic resin having a high laser absorptivity, which is an absorbing side resin. The types and colors of the transmission-side resin and the absorption-side resin are merely examples. good. Moreover, the entire lid 120 need not be made of transmission-side resin, and only the portion irradiated with the laser light L (for example, only the second wall portion 125) may be made of transmission-side resin. It is not necessary that the entire exterior main body 110 is made of the absorbing resin, and only the portion irradiated with the laser light L transmitted through the second wall portion 125 (for example, only the first wall portion 115) is made of the absorbing resin. It is sufficient if it is formed by Further, for example, when the laser beam L is transmitted through the lid 120, not all of the laser beam L needs to be transmitted. good. The same applies to the case where the exterior body main body 110 absorbs the laser light L, and the exterior body body 110 does not need to absorb all of the incident laser light L. FIG. In this case, the exterior main body 110 should be able to absorb the laser light (energy) at such a rate that the resin forming the exterior main body 110 melts.

With respect to the first wall portion 115 and the second wall portion 125 configured in this way, as shown in FIG. 4A , the transmission side of the laser light L, that is, the second wall portion 125 side (Y-axis negative direction side) When the laser beam L is emitted from the second wall portion 125 , the laser beam L transmitted through the second wall portion 125 is absorbed by the first wall portion 115 . As a result, the portion of the first wall portion 115 irradiated with the laser beam L (absorbed the laser beam L) is heated. As a result, heat is generated at the interface between the first wall portion 115 and the second wall portion 125, and as shown in FIG. 4B, part of the first wall portion 115 and part of the second wall portion 125 melt. Then, a welded portion 140 is formed, which is a portion where the first wall portion 115 and the second wall portion 125 are welded together. Further, the portion of the second wall portion 125 through which the laser beam L passes does not generate heat because it does not absorb energy, and therefore the resin does not melt. In addition, the output of the laser beam L is adjusted so that the portion of the first wall portion 115 that is melted by the laser beam L does not penetrate the first wall portion 115 . Therefore, the welded portion 140 is located inside the first wall portion 115 and the second wall portion 125 and is not exposed to the outside of the first wall portion 115 and the second wall portion 125 .

The welded portion 140 thus formed extends in the extending direction of the first wall portion 115 and the second wall portion 125 (X-axis direction in FIGS. 3 to 4B). That is, the welded portion 140 is formed so as to circle the exterior body 10 along the portion where the exterior body main body 110 and the lid body 120 are overlapped in the X-axis direction or the Y-axis direction. As a result, the body opening 111 of the exterior body body 110 is sealed by the lid 120 .

In this manner, the formation of the welded portion 140 includes a process in which the resins of the two members (the exterior body main body 110 and the lid body 120) are melted by heat and then cooled and hardened. In the process of forming the welded portion 140, when the resin is melted, the flame retardant contained in the resin, the foreign matter adhering to the resin, the resin itself, and the like evaporate to generate gas, and bubbles are generated in the welded portion 140. (voids) may occur. If a void occurs in the welded portion 140, there is a possibility that problems such as a decrease in joint strength may occur.

Therefore, in the present embodiment, a gas containing portion 118 capable of containing gas generated when the resin is melted is provided along the portion where the welded portion 140 is formed. In other words, a space capable of containing gas is provided in the gas containing portion 118 at a position continuous with the welding portion 140 . This allows the gas generated in the process of forming the welded portion 140 to escape to the gas storage portion 118 . As a result, the amount of gas remaining in the welded portion 140 can be reduced, and the number (amount) of voids generated in the welded portion 140 can be suppressed.

As described above, in the power storage device 1 according to the present embodiment, the first member (the exterior main body 110 in the present embodiment) and the second member (the lid 120 in the present embodiment) each made of resin are and The exterior body main body 110 and the lid body 120 are joined together at a welded portion 140 extending in a predetermined direction (X-axis direction in FIGS. 3 to 4B). The welded portion 140 is formed at a position not exposed to the outer surfaces of the exterior body main body 110 and the lid body 120 in a joined state. At least one of the exterior main body 110 and the lid 120 has a gas storage portion 118 that is recessed away from the other and extends in a predetermined direction along the welding portion 140 . In this embodiment, as shown in FIGS. 4A and 4B, the lid body 120 is provided with the gas storage portion 118 . The gas storage portion 118 provided on one side (the lid 120) is arranged in the thickness direction of the joint portions (the first wall portion 115 and the second wall portion 125) of the exterior main body 110 and the lid 120, respectively, or the laser beam L in the irradiation direction (Y-axis direction) of , in a direction away from the other (exterior body main body 110).

As described above, in the power storage device 1 according to the present embodiment, the joint portion between the exterior body main body 110 and the lid body 120 is formed by the welded portion 140 formed by melting and solidifying the resin. , high airtightness can be obtained. Furthermore, since the welded portion 140 is formed by transmitting and absorbing the laser light L, for example, melt marks are less likely to pose a problem in terms of appearance. When the welded portion 140 having such an advantage or superiority is formed by laser welding, at least part of the gas generated by this welding is contained in the gas containing portion 118 . This suppresses the generation of voids in the welded portion 140 . Therefore, the problem of insufficient bonding strength or reduction in bonding strength due to voids generated in the welded portion 140 is less likely to occur. Furthermore, since the gas containing portion 118 extends along the welded portion 140 extending in a predetermined direction, the occurrence of voids in the welded portion 140 is suppressed over a wide range. As described above, power storage device 1 according to the present embodiment is a power storage device having welded portion 140, which is a portion where two resin-made members are welded together, and which has improved reliability. .

In addition, as described above, each of the first member and the second member welded at welded portion 140 is a member forming part of exterior body 10 of power storage device 1 (in the present embodiment, exterior body main body 110 and lid 120). Therefore, a welded portion 140 with improved reliability is formed at a joint portion that closes (seales) the body opening 111 of the exterior body body 110 . Therefore, leakage of gas from the welded portion 140 and entry of water into the exterior body 10 from the welded portion 140 when the valve of the storage element 20 is opened are suppressed. As a result, for example, the safety of the power storage device 1 can be improved, or the product life can be extended.

One of the main body 110 and the lid 120 has a convex portion 126 extending in a predetermined direction, and the other of the main body 110 and the lid 120 has a concave portion 116 extending in the predetermined direction. have At the welded portion 140 , at least a portion of the projection 126 and at least a portion of the recess 116 are welded together while the projection 126 is engaged or fitted into the recess 116 . In the present embodiment, a protrusion 126 extending in a predetermined direction (the X-axis direction in FIGS. 3 to 4B) is provided on the lid body 120, and a recess 116 extending in the X-axis direction is provided on the exterior body. It is provided on the main body 110 .

That is, the exterior body main body 110 and the lid body 120, which are both made of resin, are joined together in a state in which the concave portion 116 and the convex portion 126 are engaged or fitted. Therefore, the mechanical strength of the joint portion (including the welded portion 140) between the exterior body main body 110 and the lid body 120 is improved. Further, the positioning and positional regulation of one of the exterior body main body 110 and the lid body 120 with respect to the other at the time of laser welding can be performed more reliably. Therefore, the exterior body main body 110 and the lid body 120 can be welded with high precision and efficiency.

Moreover, in the present embodiment, as shown in FIGS. 4A and 4B, the gas containing portion 118 is formed by a gap between the convex portion 126 and the concave portion 116. As shown in FIG.

More specifically, in the present embodiment, a combination of concave portion 116 and convex portion 126 having a size smaller than the internal space of concave portion 116 provides gas storage portion 118 extending along welded portion 140 . ing. In other words, without providing a (dedicated) recess for only the gas storage portion 118 in the exterior body main body 110 or the lid 120, a relatively simple configuration allows the gas to flow along (continuously) the welded portion 140. A housing 118 may be provided.

Further, in the power storage device 1, one of the exterior body main body 110 and the lid body 120 is formed with a vent hole 119 extending from the gas containing portion 118 to the surface of the one. In the present embodiment, as shown in FIGS. 4A and 4B , the exterior main body 110 is formed with a vent hole 119 extending from the gas storage portion 118 to the inner surface of the exterior main body 110 .

According to this configuration, the gas generated during welding and temporarily stored in the gas storage portion 118 can be released to the outside of the exterior main body 110 and the lid 120 through the ventilation holes 119 . Therefore, even if the volume of the gas containing portion 118 is small relative to the amount of gas generated during welding, the possibility of the internal pressure of the gas containing portion 118 increasing excessively is reduced. This contributes to improving the reliability of the welded portion 140 . In this embodiment, as shown in FIG. 3, for example, a plurality of vent holes 119 are arranged along the extending direction of the gas containing portion 118 at intervals. The contained gas can be efficiently discharged to the outside. However, the number of vent holes 119 arranged for one gas containing portion 118 forming one space may be one. Further, instead of the vent hole 119 that communicates between the gas storage part 118 and the surface of the exterior main body 110, a vent hole that communicates between the gas storage part 118 and the surface of the lid body 120 may be provided.

In the above, the power storage device 1 according to the embodiment has been described with a focus on the joint portion between the exterior body main body 110 and the lid body 120 . However, the structure of the joint may be different from that shown in FIGS. 3 to 4B. Therefore, a modified example of the joint portion between the exterior body main body 110 and the lid body 120 will be described below, focusing on differences from the above-described embodiment.

[2-1. Modification 1]
FIG. 5A is a cross-sectional view showing a state in which exterior body main body 110 and lid body 120 according to modification 1 of the embodiment are combined. FIG. 5B is a cross-sectional view showing a state in which exterior body main body 110 and lid body 120 are welded together according to Modification 1 of the embodiment. The positions of the cross sections in FIGS. 5A and 5B correspond to the positions of the cross sections in FIG. This also applies to each of FIGS. 6A to 7B, which will be described later.

As shown in FIGS. 5A and 5B, an exterior body main body 110 and a lid body 120 included in an exterior body 10a according to this modification have welded portions extending in a predetermined direction (the X-axis direction in FIGS. 5A and 5B). They are joined together at 140a. The welded portion 140 a is formed at a position not exposed to the outer surfaces of the exterior body main body 110 and the lid body 120 . These configurations are common to the above embodiment. In this modification, the lid body 120 has a gas storage portion 118a that is recessed in a direction away from the exterior main body 110 and that extends in a predetermined direction along the welding portion 140a. It differs from the above-described embodiment in that Specifically, the gas containing portion 118a is formed by a recess provided in a portion of the convex portion 126a.

In other words, at the joint portion between the exterior body main body 110 and the lid body 120, the convex portion 126a of the lid body 120 is in a state of being fitted or engaged with the concave portion 116 of the exterior body body 110, and the convex portion 126a has a hollow. The recess forms a gas containing portion 118a.

According to this configuration, for example, the gas containing portion 118a extending along the welding portion 140a can be provided in a state in which the concave portion 116 and the convex portion 126a are in close contact with each other over a relatively large area. Therefore, for example, it is possible to relatively increase the volume of the welded portion 140a while suppressing the generation of voids in the welded portion 140a, and to mechanically bond the convex portion 126a and the concave portion 116 more strongly. can.

In FIGS. 5A and 5B, two gas storage portions 118a are provided in the cross section of the protrusion 126a perpendicular to the extending direction (X-axis direction) of the protrusion 126a. One may be sufficient as the number of the part 118a. Also, one of the exterior body main body 110 and the lid body 120 may be provided with a vent hole that communicates the gas containing portion 118a with the surface of the one. A joint portion between the exterior body main body 110 and the lid body 120 having such a configuration will be described as Modified Example 2 below.

[2-2. Modification 2]
FIG. 6A is a cross-sectional view showing a state in which exterior main body 110 and lid 120 are combined according to Modification 2 of the embodiment. FIG. 6B is a cross-sectional view showing a state in which exterior body main body 110 and lid body 120 are welded together according to Modification 2 of the embodiment.

As shown in FIGS. 6A and 6B, the exterior body main body 110 and the lid body 120 included in the exterior body 10b according to this modification have welded portions extending in a predetermined direction (the X-axis direction in FIGS. 6A and 6B). They are joined together at 140b. Further, the gas containing portion 118b is formed by a recess provided in a portion of the convex portion 126b. This configuration is common to Modification 1 described above. However, in this modified example, one recess is provided at the top of the convex portion 126b, and this recess forms the gas storage portion 118b. Further, the lid 120 is provided with a vent hole 129 that communicates between the gas storage portion 118b and the surface of the lid 120 on the outside of the exterior body 10 .

According to this configuration, as in Modification 1, for example, the volume of the welded portion 140b can be relatively increased while suppressing the generation of voids in the welded portion 140b. and can be mechanically more firmly coupled. Furthermore, since the vent hole 129 is provided, even if the volume of the gas containing portion 118b is small relative to the amount of gas generated during welding, the internal pressure of the gas containing portion 118b does not rise excessively. do not have. This contributes to improving the reliability of the welded portion 140b.

[2-3. Modification 3]
FIG. 7A is a cross-sectional view showing a state in which an exterior main body 110c and a lid 120c are combined according to Modification 3 of the embodiment. FIG. 7B is a cross-sectional view showing a state in which an exterior body main body 110c and a lid body 120c are welded together according to Modification 3 of the embodiment.

As shown in FIGS. 7A and 7B, an exterior body main body 110c and a lid body 120c included in an exterior body 10c according to this modification have welded portions extending in a predetermined direction (the X-axis direction in FIGS. 7A and 7B). They are joined together at 140c. The welded portion 140c is formed at a position not exposed to the outer surfaces of the exterior main body 110c and the lid 120c. Also, the gas containing portion 118c extends along the welded portion 140c. These configurations are common to the above embodiment. In this modification, the exterior main body 110c has a convex portion 116c extending in a predetermined direction, and the lid 120c has a concave portion 126c extending in the predetermined direction. It differs from the above embodiment. That is, as can be seen by comparing FIG. 4B and FIG. 7B, in this modified example, the positions of the recesses and protrusions to be welded are opposite to those in the embodiment.

Even in this case, in power storage device 1 according to the present modification, at least part of the gas generated by this welding is accommodated in gas accommodating portion 118c when welded portion 140c is formed by laser welding. This suppresses the generation of voids in the welded portion 140c. Therefore, the problem of insufficient bonding strength or reduction in bonding strength due to voids generated in the welded portion 140c is less likely to occur. Furthermore, since the gas containing portion 118c extends along the welded portion 140c extending in a predetermined direction, the occurrence of voids in the welded portion 140c is suppressed over a wide range.

Further, in this modification, the cover 120c is further formed with a vent hole 129 extending from the gas storage portion 118c to the surface of the cover 120c (surface on the outside of the exterior body 10). Therefore, even if the volume of the gas containing portion 118c is small relative to the amount of gas generated during welding, the internal pressure of the gas containing portion 118c does not rise excessively. This contributes to improving the reliability of the welded portion 140c.

[2-4. Other Modifications]
Although the power storage device 1 according to the embodiment and its modification of the present invention has been described above, the present invention is not limited to this embodiment and modification thereof. In other words, the embodiments disclosed this time are illustrative in all respects and are not restrictive, and the scope of the present invention includes all changes within the meaning and range equivalent to the claims. included.

For example, it is not essential to provide a concave portion in one of the main body 110 and the lid 120 and a convex portion in the other at the joint portion between the main body 110 and the lid 120 . For example, a flat plate-like portion of the exterior main body 110 and a flat plate-like portion of the lid body 120 may be overlapped, and these flat plate-like portions may be welded by laser welding. Even in this case, along the welded portion of at least one of the exterior body main body 110 and the lid body 120, a gas storage portion having a shape recessed in a direction away from the other may be provided. As a result, the gas containing portion is provided along the welded portion formed by laser welding, and as a result, the welded portion in which the occurrence of voids is suppressed is formed.

Further, the shapes of the concave portion 116 and the convex portion 126 provided at the joint portion between the exterior body main body 110 and the lid body 120 are not limited to the shapes shown in FIG. 4A and the like. For example, a recess having a V-shaped or rectangular cross-sectional shape may be provided in one of the exterior main body 110 and the lid 120 . Even in this case, the other of the exterior body main body 110 and the lid 120 is, for example, a protrusion having a cross-sectional shape in which a part abuts the inner surface of the recess and a gap is formed adjacent to the abutting part. should be provided. As a result, a welded portion can be formed at the contact portion between the inner surface of the concave portion and the outer surface of the convex portion. In addition, the gas generated in the process of forming the welded portion can be released to the gap (that is, the gas storage portion) between the concave portion and the convex portion located along the welded portion.

Moreover, the first member and the second member that are joined by welding and that are included in power storage device 1 are not limited to the combination of exterior body main body 110 and lid body 120 . For example, the first member is the cover 120 made of the permeation-side resin, and the second member is the intermediate member made of the absorption-side resin, which is the joining portion between the cover 120 and the exterior main body 110. It may be an intermediate member interposed between the lid body 120 and the exterior body main body 110 in . In this case, lid body 120 and exterior body main body 110 can be joined via an intermediate member that is melted by laser light. Further, for example, when the lid body 120 has an opening on the upper surface and the opening is closed by a cover member, the cover member as the second member is welded to the lid body 120 as the first member by laser welding. good too. Further, for example, the exterior body main body 110 is a first member, and a busbar plate, an electrical component tray on which electrical components are placed, or a lid body 120 arranged above the power storage element unit 24 (see FIG. 2). The second member may be an inner lid or the like that closes the main body opening 111 on the inside of the . That is, by adopting the structure shown in FIG. 4A and the like in the portion where the two resin members included in the power storage device 1 are welded, a welded portion in which the number (amount) of voids is suppressed is formed. . That is, a highly reliable welded portion can be obtained.

Also, the overlapping order at the junction between the lid body 120 and the exterior body main body 110 may be reversed. For example, even if the second wall portion 125 (see FIG. 3) of the lid body 120 is arranged inside the first wall portion 115 (see FIG. 3) of the exterior main body 110 (Y-axis positive direction side in FIG. 3) good. In this case, at least a portion (for example, the entire first wall portion 115) of the exterior body main body 110 through which the laser beam L is to be transmitted is formed of the transmission-side resin, and at least the lid 120 absorbs the laser beam. It is sufficient that the portion to be reinforced (for example, the entire second wall portion 125) is made of the absorbing side resin. Thereby, the laser light L transmitted through the first wall portion 115 is absorbed by the second wall portion 125, and as a result, the first wall portion 115 and the second wall portion 125 are welded. In this case, the concave portion 116 and the convex portion 126 may not be arranged, or they may be arranged at positions facing each other (where the convex portion 126 is inserted into the concave portion 116).

Moreover, the shape of the exterior body 10 does not need to be substantially rectangular parallelepiped (box-like). For example, when joining a cylindrical exterior body with one end closed to an exterior body that closes a circular opening and is configured by a lid that is circular in plan view, for example, as shown in FIGS. 4A and 4B , A joint structure that can be used may be adopted.

Moreover, the form constructed by arbitrarily combining the plurality of components described above is also included within the scope of the present invention.

INDUSTRIAL APPLICABILITY The present invention can be applied to a power storage device having a power storage element such as a lithium ion secondary battery.

1 power storage device 10, 10a, 10b, 10c exterior body 20 power storage element 21 container 21a long side 21b short side 21c cover plate 22 electrode terminal 23 gas discharge valve 24 power storage element unit 91, 92 external terminal 110, 110c exterior body main body 111 main body opening 115 first wall 116, 126c recess 116c, 126, 126a, 126b projection 118, 118a, 118b, 118c gas storage portion 119 vent 120, 120c lid 125 second wall 129 vent 140, 140a, 140b, 140c welding part

Claims (6)

A power storage device,
comprising a first member and a second member each made of resin,
The first member and the second member are joined to each other at a welded portion extending in a predetermined direction,
The welded portion is formed at a position not exposed to the outer surfaces of the first member and the second member in a joined state,
At least one of the first member and the second member has a gas storage portion recessed in a direction away from the other, and has a gas storage portion extending in the predetermined direction along the welded portion.
storage device. one of the first member and the second member has a convex portion extending in the predetermined direction;
The other of the first member and the second member has a recess extending in the predetermined direction,
In the welding portion, at least part of the protrusion and at least part of the recess are joined by welding in a state in which the protrusion is engaged or fitted into the recess.
The power storage device according to claim 1 . The gas storage portion is formed by a gap between the convex portion and the concave portion,
The power storage device according to claim 2 . The gas containing portion is formed by a recess provided in a part of the convex portion,
The power storage device according to claim 2 . Furthermore, one of the first member and the second member is formed with a vent hole extending from the gas storage portion to the surface of the one.
The power storage device according to any one of claims 1 to 4. Each of the first member and the second member is a member forming a part of the exterior body of the power storage device,
The power storage device according to any one of claims 1 to 5.

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