JP7354556B2 - Energy storage element - Google Patents

Description

The present invention relates to a power storage element that includes a container and a shaft that penetrates a wall of the container.

BACKGROUND ART Conventionally, there has been a power storage element that includes a container and a shaft that penetrates a wall of the container. For example, Patent Document 1 discloses a secondary battery including a battery container and an external terminal. The external terminal has a welded joint that is welded to a bus bar or the like. A columnar connecting portion is provided on the lower end surface of the welded joint. The tip of the connection part is caulked with the gasket, the lid of the battery container, the insulating plate, and the base of the current collector plate being penetrated. Thereby, the external terminal is caulked and fixed to the lid of the battery container together with the insulating plate and the current collecting plate.

JP2016-91720A

When mechanical joining such as caulking is used to join the shaft that penetrates the wall of the container and the conductive member inside or outside the container, as in the case of the secondary battery in the conventional technology mentioned above. , there is a possibility that defects may occur at the joint. For example, due to stress relaxation in resin members such as gaskets, or external factors such as vibration or impact, the contact pressure between the shaft and the conductive member decreases, and as a result, the contact pressure between the shaft and the conductive member The electrical resistance of the joint may increase. To solve this problem, for example, it is conceivable to perform both mechanical joining and welding such as laser welding in order to join the shaft body and the conductive member. This improves the bonding strength at the bonded portion. However, in this case, other problems arise, such as complicating the process of joining the shaft body and the conductive member, contamination of foreign matter such as spatter generated during welding, and damage to resin members such as gaskets due to heat during welding. there is a possibility.

The present invention was achieved by the inventors of the present invention paying new attention to the above-mentioned problem, and an object of the present invention is to provide a highly reliable power storage element with a simple configuration.

In order to achieve the above object, a power storage element according to one aspect of the present invention includes a container that accommodates an electrode body, and a shaft that is disposed through a wall of the container and is electrically connected to the electrode body. and a conductive member joined to the shaft, the shaft including an insertion portion inserted into a through hole provided in the conduction member, and an end of the insertion portion outside the through hole. a protrusion that protrudes in the radial direction of the shaft body, and the conductive member has a rough surface including a region connected to the protrusion, and the conductive member has a rough surface that includes a region connected to the protrusion, It also has a rough surface portion that forms a rough surface.

According to this configuration, when the protrusion is formed by, for example, caulking the tip of the shaft, the contact stress between the protrusion and the conductive member increases locally. Thereby, the newly formed surfaces (surfaces from which the oxide film has been removed) exposed at the contact interface can be brought into contact with each other. As a result, the electrical resistance between the conductive member and the shaft body can be reduced. In this way, the power storage element according to this embodiment has a simple configuration and is highly reliable.

Further, in the electricity storage element according to one aspect of the present invention, the rough surface portion covers the protruding portion of the conductive member, which is a region connected to the protruding portion, when viewed from the axial direction of the shaft body. It may be possible to include the range in which

According to this configuration, the rough surface portion is formed in the conductive member over a relatively wide area including the entire area connected to the protrusion. Therefore, for example, even if it is difficult to make the size of the protrusion constant, there is a high possibility that the protrusion and the conductive member will be joined to each other on their new surfaces.

Further, in the power storage element according to one aspect of the present invention, the rough surface portion is an inner region around the through hole, and is located at the protruding portion of the conductive member when viewed from the axial direction of the shaft body. It may include an inner region smaller than the covered area, and the inner region may be formed more roughly than an outer region of the inner region.

According to this configuration, the roughness of the area around the through hole (inner area) where pressing force is likely to act during mechanical joining such as caulking is relatively high. This increases the possibility that the protruding portion and the conductive member will be joined to each other on their new surfaces.

Further, in the power storage element according to one aspect of the present invention, the shaft body is a stepped portion that projects in the radial direction beyond the insertion portion, and the conductive portion is connected to the protruding portion in the axial direction of the shaft body. The rough surface portion includes a step portion sandwiching the member, and the rough surface portion includes a range where the step portion and the protrusion overlap when viewed from the axial direction of the surface of the conductive member on the protrusion side. Good too.

According to this configuration, the rough surface portion of the conductive member is sandwiched between the protrusion portion and the stepped portion, so that when the conductive member and the shaft body are joined, the protrusion portion is removed from the fine convex portion of the rough surface portion. can be efficiently crushed (or efficiently crushed into minute convex parts). As a result, the possibility that the conductive member and the shaft body will be joined to each other at their new surfaces is improved.

Further, in the power storage element according to one aspect of the present invention, the protruding portion may be a caulked portion formed by caulking a tip of the insertion portion of the shaft body.

According to this configuration, since the rough surface portion is arranged on the conductive member as a joining partner of the protrusion, there is a high possibility that the protrusion and the conductive member will be joined with their new surfaces. Therefore, for example, the reliability of joining the shaft body and the conductive member is improved without caulking with a force larger than usual. Therefore, deformation of the conductive member, container, etc. due to the crimping force is suppressed. This also contributes to improving the reliability of the power storage element.

According to the present invention, it is possible to provide a highly reliable power storage element with a simple configuration.

FIG. 1 is a perspective view showing the appearance of a power storage element according to an embodiment. FIG. 2 is a perspective view showing a power storage element according to an embodiment with a lid plate of a container and a container main body separated. FIG. 2 is an exploded perspective view showing a structure for attaching an electrode terminal to a cover plate according to an embodiment. FIG. 2 is a perspective view of a current collector according to an embodiment. FIG. 4 is a cross-sectional view showing the structure of an electrode terminal and its surroundings in an XZ plane passing along the VV line in FIG. 3. FIG. FIG. 5 is a cross-sectional view showing the insertion portion of the shaft body and the structure around it in the YZ plane passing along the line VI-VI in FIG. 4. FIG. FIG. 7 is a bottom view showing an arrangement area of a rough surface portion of a current collector according to Modification 1 of the embodiment. FIG. 7 is a cross-sectional view showing a structure of a shaft body and its surroundings according to a second modification of the embodiment. FIG. 7 is a top view showing an arrangement area of a rough surface portion of a terminal main body according to Modification 2 of the embodiment.

Hereinafter, power storage elements according to embodiments and modified examples of the present invention will be described with reference to the drawings. Note that each figure is a schematic diagram and is not necessarily strictly illustrated.

Further, each of the embodiments and modifications described below represents one specific example of the present invention. The shapes, materials, components, arrangement positions and connection forms of the components, order of manufacturing steps, etc. shown in the following embodiments and modified examples are merely examples, and do not limit the present invention. Furthermore, among the constituent elements in the following embodiments and modifications, constituent elements that are not described in the independent claims will be described as arbitrary constituent elements.

In the following description and drawings, the longitudinal direction of the lid plate of the container or the direction in which the short sides of the container face each other is defined as the X-axis direction. Further, the lateral direction of the lid plate of the container or the opposing direction of the long side of the container is defined as the Y-axis direction. Further, the direction in which the container body and the lid plate are lined up or the longitudinal direction of the short side of the container is defined as the Z-axis direction. These X-axis direction, Y-axis direction, and Z-axis direction are directions that intersect with each other (orthogonal in this embodiment). Further, in this embodiment, the Z-axis direction is the up-down direction, and the positive side of the Z-axis direction is "up", but this does not limit the posture of the power storage device when it is actually used. Further, each drawing may be emphasized, omitted, or adjusted in proportion as appropriate in order to illustrate the present invention, and thus may differ from the actual shape, positional relationship, and proportion.

Furthermore, in the following embodiments and claims, expressions indicating relative directions or postures, such as parallel and perpendicular, may be used, but strictly speaking, these expressions do not mean the direction or posture. Including cases where it is not. For example, "two directions are orthogonal" does not only mean that the angle between the two directions is 90 degrees, but also that they are substantially orthogonal, that is, include a difference of, for example, several percent. also means Furthermore, in the following description, for example, the plus side in the X-axis direction refers to the side in the direction of the arrow of the X-axis, and the minus side in the X-axis direction refers to the side opposite to the plus side in the X-axis direction. The same applies to the Y-axis direction and the Z-axis direction.

(Embodiment)
[1. General explanation of energy storage elements]
First, a general description of the power storage element 10 according to the embodiment will be given using FIGS. 1 and 2. FIG. 1 is a perspective view showing the appearance of a power storage element 10 according to an embodiment. FIG. 2 is a perspective view showing the components arranged in the container 100 of the power storage element 10 according to the embodiment. Specifically, FIG. 2 is a perspective view showing the power storage element 10 with the lid plate 110 of the container 100 and the container body 101 separated.

The power storage element 10 is a secondary battery that can charge and discharge electricity, and more specifically, is a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery. The power storage element 10 is, for example, a vehicle such as an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), or a gasoline vehicle, a motorcycle, a watercraft, a snowmobile, an agricultural machine, a construction machine, Alternatively, it is used as a battery for driving a moving body such as a railway vehicle for electric railways such as a train, a monorail, or a linear motor car, or for starting an engine. Further, the power storage element 10 is used as a stationary battery or the like for home use or for a generator. Note that the power storage element 10 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 a capacitor. Furthermore, the power storage element 10 may be a primary battery that allows the user to use the stored electricity without charging it. Further, the power storage element 10 may be a battery using a solid electrolyte.

As shown in FIG. 1, the power storage element 10 includes a container 100, an electrode terminal 300 on the negative electrode side, and an electrode terminal 200 on the positive electrode side. Further, as shown in FIG. 2, inside the container 100, a current collector 120 on the positive electrode side, a current collector 130 on the negative electrode side, and an electrode body 400 are accommodated.

In addition to the above-mentioned components, the power storage element 10 may also include spacers placed on the sides of the current collectors 120 and 130, an insulating film that wraps around the electrode body 400, and the like. Furthermore, although an electrolytic solution (non-aqueous electrolyte) and the like are sealed inside the container 100 of the power storage element 10, illustration thereof is omitted. The type of electrolytic solution sealed in container 100 is not particularly limited as long as it does not impair the performance of power storage element 10, and various types can be selected.

The container 100 includes a container body 101 having a rectangular cylindrical shape and a bottom, and a lid plate 110 that is a plate-like member that closes the opening of the container body 101. The container 100 has a structure in which the interior is sealed by welding the lid plate 110 and the container body 101 after accommodating the electrode body 400 and the like therein. The materials of the lid plate 110 and the container body 101 are not particularly limited, but are preferably weldable metals such as stainless steel, aluminum, or aluminum alloy.

The electrode body 400 is a power storage element (power generation element) that includes a positive electrode plate, a negative electrode plate, and a separator and can store electricity. The positive electrode plate is an electrode plate in which a composite material layer containing a positive electrode active material is formed on a positive electrode base material layer, which is a long strip-shaped current collecting foil made of aluminum or an aluminum alloy. The negative electrode plate is an electrode plate in which a composite material layer containing a negative electrode active material is formed on a negative electrode base material layer, which is a long strip-shaped current collecting foil made of copper or a copper alloy. The separator is a microporous sheet made of resin or the like. The electrode body 400 is formed by winding a separator between a positive electrode plate and a negative electrode plate.

The electrode body 400 is a negative electrode formed by laminating a base material layer of a negative electrode plate at one end (the end on the negative side in the X-axis direction in FIG. 2) in the winding axis direction (X-axis direction in this embodiment). It has a side end portion 411a. Further, the electrode body 400 has a positive electrode side end portion 421a formed by laminating the base material layer of the positive electrode plate at the other end in the winding axis direction (the end on the positive side in the X-axis direction in FIG. 2). The negative electrode side end portion 411a is joined to the current collector 130, and the positive electrode side end portion 421a is joined to the current collector 120.

Note that in this embodiment, the cross-sectional shape of the electrode body 400 is shown as an oval shape, but it may also be an elliptical shape, a circular shape, a polygonal shape, or the like. Furthermore, the type of electrode body 400 is not limited to the wound type. For example, the power storage element 10 is equipped with a laminated electrode body in which flat plates are laminated, or an electrode body having a bellows-like structure in which long strip-shaped plates are laminated by repeating mountain folds and valley folds. It's okay to be hit.

The electrode terminal 200 is a positive terminal electrically connected to the positive electrode of the electrode body 400 via the current collector 120. The electrode terminal 300 is a negative electrode terminal electrically connected to the negative electrode of the electrode body 400 via the current collector 130. The electrode terminals 200 and 300 are attached to the cover plate 110 disposed above the electrode body 400 via upper insulating members 250 and 350.

Note that the material of the current collector 120 is not limited, but is made of, for example, aluminum or an aluminum alloy, like the positive electrode base material layer of the electrode body 400. Further, the material of the current collector 130 is not limited, but is made of, for example, copper or a copper alloy, like the negative electrode base material layer of the electrode body 400.

[2. Structure for attaching electrode terminal to container]
Next, a structure for attaching the electrode terminal to the cover plate 110 in the power storage element 10 according to the present embodiment will be explained using FIGS. 3 to 6. In this embodiment, the structure for attaching the electrode terminals 200 and 300 to the cover plate 110 is the same. Therefore, below, the attachment structure of the positive electrode terminal 200 to the cover plate 110 will be explained, and the illustration and description of the attachment structure of the negative electrode terminal 300 to the cover plate 110 will be omitted.

FIG. 3 is an exploded perspective view showing a structure for attaching the electrode terminal 200 to the cover plate 110 according to the embodiment. FIG. 4 is a perspective view of the current collector 120 according to the embodiment. FIG. 5 is a cross-sectional view showing the structure of the electrode terminal 200 and its surroundings in the XZ plane passing along the line VV in FIG. Note that in FIG. 3, the shaft body 210 is shown in a state before being caulked, and in FIG. 5, the shaft body 210 is shown in a caulked state. In addition, in FIGS. 3 and 4, the approximate placement area of the rough surface portion 124 in the current collector 120 is represented by a dotted area, and in FIG. 5, the approximate placement area of the rough surface portion 124 is indicated by a thick line. Schematically represented by a dotted line. In FIG. 4, a connection region 125 of the current collector 120 that is connected to the protrusion 213 is represented by a dotted circle, and an inner region 126 around the through hole 123 is represented by a dotted circle. There is. FIG. 6 is a cross-sectional view showing the structure of the insertion portion 211 of the shaft body 210 and its surroundings in the YZ plane passing along the line VI-VI in FIG.

As shown in FIGS. 3 to 6, the electrode terminal 200 includes a terminal body 201 and a shaft body 210. In this embodiment, the shaft body 210 and the terminal body 201 are integrally provided in the electrode terminal 200. The electrode terminal 200, like the positive electrode base material layer of the electrode body 400, is made of aluminum, aluminum alloy, or the like.

The electrode terminal 200 is insulated from the container 100 by an upper insulating member 250 and a lower insulating member 280. Specifically, the upper insulating member 250 is disposed between the terminal body 201 and the lid plate 110 of the container 100. The lid plate 110 is an example of a wall portion that the container 100 has. The shaft body 210 fixed to the terminal body 201 has a through hole 252 in the upper insulating member 250, a through hole 112 in the cover plate 110, a through hole 282 in the lower insulating member 280, and a shaft connecting portion 121 of the current collector 120. It passes through the through hole 123 formed in the hole 123 and is caulked as shown in FIG. Thereby, the upper insulating member 250, the lower insulating member 280, and the current collector 120 are fixed to the cover plate 110 together with the electrode terminal 200.

The upper insulating member 250 according to this embodiment has a cylindrical portion 259 (see FIG. 5) that forms a through hole 252. The cylindrical portion 259 has a role of maintaining airtightness between the shaft body 210 and the through hole 112 of the cover plate 110. That is, the upper insulating member 250 also has a role as a so-called gasket. Further, as shown in FIGS. 3 and 5, the upper insulating member 250 has a side wall portion 258 that surrounds an end surface in a direction perpendicular to the thickness direction (Z-axis direction) of the terminal body 201. Side wall portion 258 functions, for example, as a member that prevents conduction between electrode terminal 200 and an external member disposed near power storage element 10 . Further, the side wall portion 258 functions as a rotation stopper for the electrode terminal 200, for example, during manufacture and use of the power storage element 10.

Note that each of the upper insulating member 250 and the lower insulating member 280 is made of polypropylene (PP), polyethylene (PE), polystyrene (PS), polyphenylene sulfide resin (PPS), polyphenylene ether (PPE (including modified PPE)), polyethylene Terephthalate (PET), polybutylene terephthalate (PBT), polyetheretherketone (PEEK), tetrafluoroethylene perfluoroalkyl vinyl ether (PFA), polytetrafluoroethylene (PTFE), polyethersulfone (PES), ABS It is formed of an insulating member such as resin or a composite material thereof.

In this way, the electrode terminal 200 fixed to the cover plate 110 via the upper insulating member 250 is joined to the current collector 120 inside the container 100 in the state shown in FIG. 5. Specifically, the electrode terminal 200 has a large-diameter portion 202 provided at the base of the shaft body 210 that is larger than the outer diameter of the shaft body 210, and the large-diameter portion 202 is provided on the upper insulating member 250. It is buried in the recessed part 251. The large diameter portion 202 functions, for example, as a portion that improves the strength of the electrode terminal 200. Further, the shaft body 210 has an insertion portion 211 that is a shaft portion having a smaller outer diameter than the shaft body 210, and the insertion portion 211 is inserted into the through hole 123 of the current collector 120, and the insertion portion 211 is inserted into the through hole 123 of the current collector 120, and the outside of the through hole 123 ( The protrusion 213 (see FIG. 5) is formed by caulking the container 100 (inner side of the container 100). That is, in the present embodiment, the protruding portion 213 is a caulked portion formed by caulking the tip of the insertion portion 211.

More specifically, the current collector 120 includes a shaft connecting portion 121 that is a portion connected to the shaft 210 and a pair of legs extending from the shaft connecting portion 121 to the electrode body 400 side. 122. Current collector 120 according to this embodiment is an example of a conductive member connected to the shaft. The pair of legs 122 is joined to the positive electrode side end 421a of the electrode body 400 by a predetermined method such as ultrasonic joining. The pair of leg parts 122 has a joint surface part 122a joined to the positive electrode side end part 421a of the electrode body 400 on the inner surfaces facing each other. In FIG. 4, the joint surface portion 122a is represented as an oval region surrounded by dotted lines. The entire area of the bonding surface portion 122a does not need to be bonded to the electrode body 400, and is defined as a region that may be bonded to the electrode body 400 depending on the shape or size of the electrode body 400.

The shaft connecting portion 121 is a plate-shaped portion having a through hole 123, and has a rough surface portion 124 on a back surface 121a (surface on the minus side in the Z-axis direction). The rough surface portion 124 is a portion that includes a region connected to the protrusion portion 213 and forms a surface rougher than surfaces other than the rough surface portion 124 . In this embodiment, as shown in FIG. 4, a rough surface portion 124 is provided in an elongated region in the X-axis direction that includes the periphery of the through hole 123 on the back surface 121a. The rough surface portion 124 in this manner is formed, for example, by subjecting a metal plate, which is the base material of the current collector 120, to knurling using a rolling method. That is, by knurling, a band-shaped uneven portion in which minute unevenness is arranged in a line is formed on the base material. Furthermore, the base material on which the strip-shaped uneven portion is formed is subjected to press processing, etc., thereby producing the current collector 120 in which a portion of the strip-shaped uneven portion is provided as the rough surface portion 124. According to this process, a plurality of current collectors 120 each having a rough surface portion 124 can be efficiently manufactured. Note that there is no particular limitation on the method of forming the rough surface portion 124. For example, by pressing the shaft connection portion 121 of the current collector 120 that does not have the rough surface portion 124 using a mold having minute irregularities, the back surface 121a of the shaft connection portion 121 may be The rough surface portion 124 may be formed in accordance with the above. Further, the shape and size of the arrangement area of the rough surface part 124 shown in FIG. may be determined.

In this way, the power storage element 10 according to the present embodiment is arranged to penetrate the container 100 that houses the electrode body 400 and the wall (lid plate 110) of the container 100, and is electrically connected to the electrode body 400. A current collector 120, which is an example of a conductive member joined to the shaft body 210, is provided. The shaft body 210 includes an insertion portion 211 that is inserted into a through hole 123 provided in the current collector 120, and a radial direction of the shaft body 210, which is disposed at the outer end of the through hole 123 of the insertion portion 211. It has a protruding portion 213 that protrudes. The current collector 120 has a rough surface portion 124 that includes a region connected to the protrusion portion 213 and is rougher than the surface other than the rough surface portion 124 .

According to this configuration, when the protruding part 213 is formed by mechanical joining such as caulking the tip of the insertion part 211 of the shaft body 210, the contact stress between the protruding part 213 and the current collector 120 is localized. increase. Specifically, in this embodiment, as shown in FIG. 6, a plurality of minute convex portions are arranged side by side on the rough surface portion 124 formed on the back surface 121a of the shaft connecting portion 121. 124 and the protrusion 213 are pressed against each other by the pressing force during caulking. As a result, when the base material of the shaft body 210 and the base material of the current collector 120 are made of the same kind of metal, each of the plurality of minute convex parts of the rough surface part 124 bites into the protrusion part 213 or/ Then, it is crushed by the protrusion 213. That is, in the portion where the protruding portion 213 and the rough surface portion 124 come into contact with each other, minute fractures are likely to occur on each other's surfaces. As a result, the newly formed surfaces (surfaces from which the oxide film has been removed) of the base material exposed at the contact interface between the shaft body 210 and the current collector 120 can be brought into contact with each other. Thereby, the electrical resistance between the current collector 120 and the shaft body 210 can be reduced. More specifically, by bringing the newly formed surfaces into contact with each other at the contact interface between the shaft body 210 and the current collector 120, there is a possibility that at least a portion of the contact interface will be in a solid-phase bonded state.

Further, the bonding strength between the current collector 120 and the shaft body 210 can also be improved. Therefore, there is no need to perform welding such as laser welding to join the current collector 120 and the shaft body 210, and therefore there is no possibility of deformation or damage of the resin members such as the lower insulating member 280 due to heat during welding. This improves the reliability of airtightness at the location where the shaft body 210 of the container 100 penetrates. In this way, the power storage element 10 according to the present embodiment has a simple configuration and is a highly reliable power storage element.

An example of the surface of the current collector 120 other than the rough surface portion 124 to which the surface roughness of the rough surface portion 124 is compared is the joint surface portion 122a of the leg portion 122. The bonding surface portion 122a is a portion that forms a surface to be bonded to the electrode body 400, and for example, ultrasonic bonding is used for this bonding. Therefore, from the viewpoint of improving the joining accuracy or suppressing the generation of metal powder (contamination) during the joining operation, it is preferable that the roughness of the joining surface portion 122a is small. On the other hand, the rough surface portion 124 is a portion obtained by performing metal processing such as knurling, and is a portion whose surface roughness is intentionally increased. Note that when the current collector 120 is manufactured using a base material with a large surface roughness, the current collector 120 is manufactured by reducing the roughness of only the portion corresponding to the bonding surface portion 122a by polishing or the like. It's okay. Even in this case, the rough surface portion 124 is provided in the current collector 120 as a portion forming a surface rougher than the bonding surface portion 122a.

In the present embodiment, the rough surface portion 124 is a region connected to the protrusion 213 of the current collector 120 when viewed from the axial direction (Z-axis direction) of the shaft body 210. Contains the area covered.

Specifically, in FIG. 4, the connection area 125, which is the area of the current collector 120 that is connected to the protrusion 213 (the area covered by the protrusion 213), is represented by a dotted circle; 125 is included in the rough surface portion 124. This is also shown in FIG.

As described above, in this embodiment, the rough surface portion 124 is formed in a relatively wide area including the entire area of the connection area 125. Therefore, for example, even if it is difficult to make the size of the protrusion 213 formed by caulking constant, there is a high possibility that the protrusion 213 and the current collector 120 will be joined with their new surfaces. Specifically, when manufacturing a plurality of power storage elements 10, individual differences may occur in the size of the protrusion 213. However, in the power storage element 10 according to the present embodiment, since the rough surface portion 124 is formed in a relatively wide area on the current collector 120, there is no possibility that the protruding portion 213 protrudes beyond the connection area 125. Hard to occur. That is, in each of the plurality of power storage elements 10, the reliability of the connection between the shaft body 210 and the current collector 120 is improved. Therefore, when manufacturing a plurality of power storage elements 10, the quality of each power storage element 10 can be maintained or improved.

Furthermore, in this embodiment, the insertion portion 211 is a shaft portion with a small outer diameter arranged at the end of the shaft body 210, and a stepped portion 212 is formed at the base of the insertion portion 211 due to the difference in outer diameter. ing. That is, as shown in FIG. 6, the shaft body 210 has a stepped portion 212 that projects further in the radial direction than the insertion portion 211. The stepped portion 212 is arranged so that the shaft connecting portion 121 of the current collector 120 is sandwiched between the stepped portion 212 and the protruding portion 213 in the axial direction (Z-axis direction) of the shaft 210. As can be seen from FIGS. 5 and 6, the rough surface portion 124 is a stepped portion on the surface (back surface 121a) of the current collector 120 on the side of the protrusion 213 when viewed from the axial direction (Z-axis direction) of the shaft body 210. 212 and the protrusion 213 include an overlapping range.

According to this configuration, the rough surface portion 124 of the current collector 120 is sandwiched between the protruding portion 213 and the stepped portion 212. Therefore, when joining the current collector 120 and the shaft body 210, the protruding portion 213 can efficiently crush the fine convex portions on the rough surface portion 124 (or be efficiently crushed by the fine convex portions). . More specifically, the caulking force when forming the protrusion 213 is received by the stepped portion 212 located at a position facing the protrusion 213 with the shaft connection portion 121 of the current collector 120 interposed therebetween. Therefore, the caulking force efficiently acts as a force for joining the protruding portion 213 and the rough surface portion 124. As a result, the possibility that the current collector 120 and the shaft body 210 will be joined at their new surfaces is improved.

Furthermore, in the present embodiment, the protruding portion 213 is a caulked portion formed by caulking the tip of the insertion portion 211 of the shaft body 210.

That is, in the present embodiment, the rough surface portion 124 is disposed on the current collector 120 as a joining partner of the protruding portion 213, so that the protruding portion 213 and the current collector 120 can be joined with their new surfaces. Highly sexual. Therefore, for example, the reliability of joining the shaft body 210 and the current collector 120 is improved without caulking with a force larger than usual. Therefore, deformation of the current collector 120, the container 100, etc. due to the crimping force is suppressed. This also contributes to improving the reliability of power storage element 10.

Here, the rough surface portion 124 does not need to have uniform roughness over the entire region of the rough surface portion 124. For example, the rough surface portion 124 is the inner region 126 (see FIG. 4) around the through hole 123 of the current collector 120, and is the rough surface portion 124 when viewed from the axial direction (Z-axis direction) of the shaft body 210 of the current collector 120. The inner region 126 may be smaller than the range covered by the protrusion 213 (the connection region 125 in FIG. 4) in the case, and the inner region 126 may be formed more roughly than the region outside the inner region 126.

The inner region 126 is a region around the through hole 123 where pressing force is likely to act during mechanical joining operations such as caulking. Therefore, since the roughness of the inner region 126 is greater than that of the outer region, the possibility that the protruding portion 213 and the current collector 120 will be joined to each other on their new surfaces is improved. In this embodiment, as shown in FIGS. 5 and 6, the shaft body 210 has a stepped portion 212, and the area of the rough surface portion 124 immediately below the stepped portion 212 in FIGS. , is the area that receives the greatest pressing force. Therefore, in the rough surface portion 124, it is preferable that the roughness in the region overlapping with the step portion 212 is greater than the roughness in other regions when viewed from the axial direction of the shaft body 210. That is, a region of the rough surface portion 124 that overlaps with the step portion 212 may be provided as the inner region 126.

Note that the rough surface portion 124 may be composed of only the inner region 126. In other words, the rough surface portion 124 does not need to be disposed over the entire region of the current collector 120 that is connected to the protruding portion 213 . The rough surface portion 124 is formed at least around the through hole 123 where pressing force is likely to act during mechanical bonding work, thereby reducing the possibility that the protruding portion 213 and the current collector 120 will be bonded to each other on their new surfaces. can be improved. That is, the reliability of power storage element 10 can be improved.

Although the power storage element 10 according to the embodiment has been described above, the power storage element 10 may include the shaft body 210 or the current collector 120 in a different form from that shown in FIGS. 2 to 6. Therefore, modifications of the shaft body 210 or the current collector 120 in the power storage element 10 will be described below, focusing on the differences from the above embodiment.

(Modification 1)
FIG. 7 is a bottom view showing the arrangement area of the rough surface portion 124a of the current collector 120a according to Modification 1 of the embodiment. Specifically, in FIG. 7, the current collector 120a is illustrated when viewed from the negative side in the Z-axis direction, and the approximate arrangement area of the rough surface portion 124a is represented by a dotted area. Further, in FIG. 7, each of the connection area 125 and the inner area 126 is represented by a dotted circle.

In the current collector 120a according to the present modification shown in FIG. 7, a rough surface portion 124a is arranged in a circular region centered on the through hole 123 on the back surface 121a of the shaft connection portion 121. Even when the rough surface portion 124a is formed in such a shape and size, the new surfaces exposed at the contact interface between the shaft body 210 and the current collector 120a can be brought into contact with each other. Thereby, the electrical resistance between the current collector 120a and the shaft body 210 can be reduced.

Furthermore, in this modification, the rough surface portion 124a includes a connection region 125 that is a region connected to the protrusion 213 and covered by the protrusion 213. Therefore, a situation in which the protruding portion 213 protrudes beyond the connection area 125 is unlikely to occur. Therefore, when manufacturing a plurality of power storage elements 10, the quality of each power storage element 10 can be maintained or improved.

Furthermore, in this modification, the rough surface portion 124a includes an inner region 126 around the through hole 123, and the inner region 126 is formed rougher than the region outside the inner region. In other words, the roughness of the inner region 126 around the through hole 123, on which pressing force is likely to act during the mechanical joining operation, is relatively large. Therefore, the possibility that the protruding portion 213 and the current collector 120a will be joined to each other at their newly formed surfaces is improved. In addition, the rough surface part 124a may be comprised only of the inner area|region 126 similarly to the rough surface part 124 based on embodiment.

(Modification 2)
FIG. 8 is a sectional view showing a structure of a shaft body 210a and its surroundings according to a second modification of the embodiment. Note that the position of the cross section in FIG. 8 corresponds to the position of the cross section in FIG. 5. FIG. 9 is a top view showing the arrangement area of the rough surface portion 204 of the terminal main body 201a according to the second modification of the embodiment. Specifically, FIG. 9 shows the terminal main body 201a of the electrode terminal 200a when viewed from the positive side in the Z-axis direction, and the approximate placement area of the rough surface portion 204 is represented by a dotted area. ing. Further, in FIG. 7, a connection region 225, which is a region connected to the protrusion 213a and is a range covered by the protrusion 213a, is represented by a dotted circle.

As shown in FIGS. 7 and 8, in the power storage element 10a according to the present modification, the current collector 120b is provided with a shaft 210a that penetrates the wall (cover plate 110) of the container 100. A shaft body 210a is connected to a terminal main body 201a disposed on the outside of the terminal body 201a. That is, in this modification, the terminal body 201a is an example of a conductive member connected to the shaft. The shaft body 210a is disposed between the terminal main body 201a and the cover plate 110, and is disposed so as to penetrate through the upper insulating member 250a. Further, the cylindrical portion 289 of the lower insulating member 280 maintains airtightness between the shaft body 210a and the through hole 112 of the cover plate 110.

In this modification, the shaft body 210a includes an insertion portion 211a inserted into the through hole 205 provided in the terminal body 201a, and a shaft body 210a disposed at the outer end of the through hole 205 of the insertion portion 211a. It has a protrusion 213a that protrudes in the radial direction. The terminal main body 201a has a rough surface portion 204 that includes a region connected to the protruding portion 213a and is rougher than surfaces other than the rough surface portion 204.

More specifically, in this modification, the shaft body 210a and the terminal main body 201a are connected by caulking, and the protruding portion 213a is a caulked portion formed by caulking the tip of the insertion portion 211a. That is, in this modification, the terminal main body 201a outside the container 100 and the current collector 120b inside the container 100 are mechanically and electrically connected by caulking the shaft body 210a outside the container 100. has been done.

Even in this case, the rough surface portion 204 is arranged on the terminal main body 201a as a mating partner of the protruding portion 213a. This increases the possibility that the protruding portion 213a and the terminal main body 201a will be joined with their new surfaces, and as a result, the electrical resistance between the terminal main body 201a and the shaft body 210a can be reduced.

Furthermore, the power storage element 10a according to this modification has the same characteristics as the power storage element 10 according to the embodiment, such as the rough surface portion 204 being formed in a relatively wide area including the entire area of the connection region 225. I can do it. That is, according to the power storage element 10a, the same effects as those achieved by the characteristics of the power storage element 10 according to the embodiment can be obtained.

In this way, in the power storage element 10a having a structure in which the shaft body 210a of the current collector 120b is caulked on the outside of the terminal body 201a, since the terminal body 201a has the rough surface portion 204, the terminal body 201a and the shaft body 210a can be separated. The reliability of the joints is improved. As a result, a power storage element 10a with improved reliability can be obtained.

(Other embodiments)
The power storage device according to the present invention has been described above based on the embodiment and its modification. However, the present invention is not limited to the above embodiments and modifications. Unless departing from the spirit of the present invention, the present invention also includes various modifications that can be thought of by those skilled in the art to the above-described embodiments or modified examples, or forms constructed by combining a plurality of the above-described components. Included within the scope of.

For example, the protruding portion 213 of the shaft body 210 is not limited to a caulking portion. For example, the protrusion may be formed by a female threaded member (for example, a nut) having a threaded hole into which the shaft body is inserted. That is, as a mechanical joining method for connecting the current collector 120 and the shaft, fastening using the shaft and a nut may be used. Even in this case, the fastening force generated by tightening the nut acts as a bonding force between the nut, which is a protrusion, and the current collector 120. As a result, the rough surface portion 124 disposed on the current collector 120 and the nut are brought into pressure contact with each other, and as a result, the possibility that the nut and the current collector 120 will be joined to each other on their new surfaces is improved. The same applies when the shaft body 210a passes through the terminal body 201a as in Modification 2, and as a mechanical joining method for connecting the terminal body 201a and the shaft body, fastening using the shaft body and a nut is possible. may be used.

Further, the configurations such as the rough surface portions 124 shown in FIGS. 3 to 9 may not be employed on both the positive electrode side and the negative electrode side of the power storage element 10. By employing a configuration such as the rough surface portion 124 on either the positive electrode side or the negative electrode side of the power storage element 10, the reliability of the connection between the shaft body and the conductive member (current collector or terminal body) on at least one of the positive electrode sides and the negative electrode side is improved. will be improved.

Note that the structure of the rough surface portion 124 and the like shown in FIGS. 3 to 9 is more effective when adopted on the positive electrode side of the positive electrode side and the negative electrode side, for example, for the following reasons.

That is, when comparing aluminum used for the positive electrode and copper used for the negative electrode in the power storage element 10, aluminum has a higher electrical resistance than copper. On the other hand, since aluminum members generally have lower yield strength than copper members, they can easily follow surface roughness during fastening such as caulking, and as a result, the effects of the present invention can be more easily achieved. For this reason, in a lithium ion secondary battery, it is better to apply the present invention to the positive electrode side, which is generally made of an aluminum member, than to apply the present invention to the negative electrode side, which is generally made of a copper member. , it is easy to obtain the effects of the present invention. Further, compared to the case where the rough surface portion according to the present invention is employed on both the positive electrode side and the negative electrode side, relatively large effects can be obtained at lower cost.

Further, although the electrode terminal 200 integrally includes a terminal body 201 and a shaft body 210, the electrode terminal 200 may be configured by combining a terminal body and a shaft body that are separate from each other. For example, an electrode terminal including a terminal body and a shaft body may be produced by press-fitting the end of the shaft body into a bottomed or bottomless hole provided in the terminal body.

The present invention can be applied to power storage elements such as lithium ion secondary batteries.

10, 10a Energy storage element 100 Container 110 Cover plate 120, 120a, 120b, 130 Current collector 122a Joint surface portion 124, 124a, 204 Rough surface portion 125, 225 Connection area 126 Inner area 200, 200a, 300 Electrode terminal 201, 201a Terminal body 210, 210a Shaft body 211, 211a Insertion part 212 Step part 213, 213a Projection part 400 Electrode body

Claims (4)

a container containing an electrode body;
a shaft body disposed through the wall of the container and electrically connected to the electrode body;
comprising a conductive member joined to the shaft,
The shaft body is
an insertion portion inserted into a through hole provided in the conductive member;
a protrusion that protrudes in the radial direction of the shaft body and is disposed at an outer end of the through hole of the insertion portion;
The conductive member has a rough surface portion that includes a region connected to the protrusion portion by pressure contact, and has a rough surface portion that is rougher than a surface other than the rough surface portion;
The rough surface portion includes an inner region around the through hole that is smaller than a range of the conductive member covered by the protrusion when viewed from the axial direction of the shaft body,
The inner region is formed to be rougher than a region outside the inner region and within the rough surface portion,
Energy storage element. The rough surface portion is a region connected to the protrusion, and includes a range of the conductive member covered by the protrusion when viewed from the axial direction of the shaft body.
The electricity storage element according to claim 1 . The shaft body has a step portion that protrudes in the radial direction beyond the insertion portion, and has a step portion that sandwiches the conductive member with the protrusion in the axial direction of the shaft body;
The rough surface portion includes a range where the step portion and the protrusion overlap when viewed from the axial direction of the surface of the conductive member on the protrusion side.
The electricity storage element according to claim 1 or 2 . The protruding portion is a caulked portion formed by caulking the tip of the insertion portion of the shaft body.
The electricity storage element according to any one of claims 1 to 3 .

Images