JP7669652B2 - Energy storage element - Google Patents

Description

The present invention relates to an energy storage element having a container.

Conventionally, there is known an energy storage element that includes a container and has a through hole formed in the container that is blocked by a blocking member. For example, Patent Document 1 discloses a sealed battery (energy storage element) that has a through hole formed in a battery case (container) that is sealed by a sealing member (blocking member).

JP 2012-248336 A

In a configuration in which a through hole formed in a container is blocked with a blocking member, as in the conventional energy storage element described above, the blocking member may be joined to the container by laser welding, and the through hole may be blocked with the blocking member. However, the inventors of the present application have found that in this case, pinholes may occur in the laser welded portion (melted portion) of the container and the blocking member, resulting in poor bonding, poor appearance, and reduced bonding quality. If poor bonding occurs between the container and the blocking member, it may become impossible to maintain a sealed state inside the container, the electrolyte inside the container may leak out, the poorly bonded area may corrode, and other problems may occur.

The present invention was made by the inventors of the present application by focusing on the above-mentioned problem, and aims to provide an energy storage element that can improve the bonding quality of the container and the closing member.

In order to achieve the above object, an energy storage element according to one aspect of the present invention comprises a container having a through hole formed therein, and a blocking member joined to the container to block the through hole, the container and the blocking member are arranged overlapping in the penetration direction of the through hole, a laser welded portion is formed at the overlapping portion where the container and the blocking member are joined by laser welding, and a space is formed between the container and the blocking member, extending from the laser welded portion toward the through hole.

According to this, in the energy storage element, the container and the blocking member are arranged overlapping in the penetration direction of the through hole of the container, a laser weld is formed in the overlapping portion, and a space is formed between the container and the blocking member extending from the laser weld toward the through hole. Here, if a space is formed extending from the laser welded portion of the container and the blocking member toward the through hole during laser welding, gas generated during laser welding escapes into the space, and the occurrence of pinholes can be suppressed. In other words, if a space extending from the laser weld toward the through hole is formed between the container and the blocking member, it can be seen that a space extending from the laser welded portion of the container and the blocking member toward the through hole is formed during laser welding. This allows gas generated during laser welding to escape into the space, and the configuration can suppress the occurrence of pinholes, thereby realizing an energy storage element with improved joint quality between the container and the blocking member.

The space may include a first space arranged adjacent to the laser weld on the through-hole side of the laser weld, and a second space arranged connected to the first space on the through-hole side of the first space and having a larger volume than the first space.

According to this, a first space is arranged on the through-hole side of the laser welded portion, and a second space having a larger volume than the first space is arranged on the through-hole side of the first space, so that gas generated at the laser welded portion escapes to the first space and then to the second space. This allows the gas generated at the laser welded portion to escape effectively, thereby improving the joining quality of the container and the closing member.

The space may be formed by recessing at least one of the container and the closing member.

This makes it easy to form a space by recessing at least one of the container and the closing member. This makes it easy to improve the joining quality of the container and the closing member.

The blocking member may have a shaft portion that is inserted into the through hole, and a gap that is connected to the space and penetrates the container may be formed between the shaft portion and the inner surface of the through hole.

With this, a gap that connects to the above-mentioned space is formed between the shaft of the closure member and the inner surface of the through hole of the container, so that gas generated at the laser welded portion can escape into the container through the gap. This allows the gas generated at the laser welded portion to escape effectively, improving the joining quality of the container and the closure member.

At least one of the container and the closing member may have a protrusion that protrudes toward the other and abuts against the other, and is disposed within the space.

By providing a protrusion on at least one of the container and the closing member that abuts against the other, the space is formed by the protrusion, making it easy to form the space. This makes it easy to improve the joining quality of the container and the closing member.

The present invention can be realized not only as such an energy storage element, but also as a combination of a container and a closing member.

The energy storage element of the present invention can improve the joining quality of the container and the closing member.

1 is a perspective view showing the appearance of an energy storage element according to an embodiment; FIG. 2 is an exploded perspective view showing each component of the energy storage element according to the embodiment. 5A and 5B are a perspective view and a cross-sectional view showing the configuration of the periphery of a through hole of a lid body and a closing member in the embodiment. 4 is a cross-sectional view showing a structure in which a closing member is joined to a lid body in the embodiment. FIG. 10 is a cross-sectional view showing the configuration of the periphery of the through hole of the lid body and the closing member in the first modified example of the embodiment. FIG. 11 is a cross-sectional view showing the configuration of the periphery of a through hole of a lid body and a closing member in a second modified example of the embodiment. FIG. 13A and 13B are a perspective view and a cross-sectional view showing the configuration of the periphery of a through hole of a lid body and a closing member in a third modified example of an embodiment. 13 is a cross-sectional view showing a configuration in which a closing member is joined to a lid body according to a third modified example of the embodiment. FIG. 13 is a cross-sectional view showing the configuration of the periphery of the through hole of the lid body and the closing member in a fourth modified example of the embodiment. FIG.

The following describes an energy storage element according to an embodiment of the present invention (including its variations) with reference to the drawings. Note that the embodiments described below are all comprehensive or specific examples. The numerical values, shapes, materials, components, component placement and connection forms, manufacturing processes, and the order of manufacturing processes shown in the following embodiments are merely examples and are not intended to limit the present invention. In each figure, dimensions are not strictly illustrated. In each figure, the same or similar components are given the same reference numerals.

In the following description and drawings, the X-axis direction is defined as the direction in which a pair of electrode terminals (positive and negative, hereinafter the same) of the storage element, the direction in which a pair of current collectors are arranged, or the direction in which the short sides of the container face each other. The Y-axis direction is defined as the direction in which the long sides of the container face each other, or the thickness direction of the container. The Z-axis direction is defined as the direction in which the container body and the lid of the container are arranged, the direction in which the through-hole of the container (lid) penetrates, or the up-down direction. These X-axis, Y-axis, and Z-axis directions intersect each other (orthogonal in this embodiment). Note that, depending on the mode of use, the Z-axis direction may not be the up-down direction, but for convenience of explanation, the following description will be given assuming that the Z-axis direction is the up-down direction.

In the following description, for example, the positive X-axis direction refers to the direction of the X-axis arrow, and the negative X-axis direction refers to the opposite direction to the positive X-axis direction. The same applies to the Y-axis and Z-axis directions. Furthermore, expressions indicating relative directions or attitudes, such as parallel and perpendicular, also include cases where the directions or attitudes are not strictly speaking the same. For example, saying that two directions are perpendicular does not only mean that the two directions are completely perpendicular, but also means that the directions are substantially perpendicular, that is, there is a difference of, for example, about a few percent.

(Embodiment)
[1 General Description of Energy Storage Element 10]
First, an overall description of an energy storage element 10 according to the present embodiment will be given with reference to Figures 1 to 3. Figure 1 is a perspective view showing the external appearance of an energy storage element 10 according to the present embodiment. Figure 2 is an exploded perspective view showing each component of the energy storage element 10 according to the present embodiment.

The energy storage element 10 is a secondary battery (single cell) that can charge and discharge electricity, specifically a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery. The energy storage element 10 is used as a battery for driving or starting an engine of a moving object such as an automobile, motorcycle, watercraft, ship, snowmobile, agricultural machinery, construction machinery, or railroad vehicle for electric railway. Examples of the automobile include an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and a gasoline-powered vehicle. Examples of the railroad vehicle for electric railway include a train, a monorail, a linear motor car, and a hybrid train equipped with both a diesel engine and an electric motor. The energy storage element 10 can also be used as a stationary battery for home use or for a generator.

The energy 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 may be a capacitor. The energy storage element 10 may not be a secondary battery, but may be a primary battery that can use stored electricity without the user having to charge it. The energy storage element 10 may be a battery that uses a solid electrolyte. The energy storage element 10 may be a pouch-type energy storage element. In this embodiment, the energy storage element 10 is illustrated as having a flat rectangular parallelepiped (angled) shape, but the shape of the energy storage element 10 is not limited to a rectangular parallelepiped shape, and may be a cylindrical shape, an oval cylindrical shape, or a polygonal prism shape other than a rectangular parallelepiped, etc.

As shown in FIG. 1, the energy storage element 10 includes a container 100, a blocking member 200, a pair of electrode terminals 300 (positive and negative), and a pair of upper gaskets 400 (positive and negative). As shown in FIG. 2, the container 100 contains a pair of lower gaskets 500 (positive and negative), a pair of current collectors 600 (positive and negative), and an electrode body 700. Note that an electrolyte (non-aqueous electrolyte) is sealed inside the container 100, but is not shown. There is no particular limit to the type of electrolyte as long as it does not impair the performance of the energy storage element 10, and various electrolytes can be selected. In addition to the above components, a spacer disposed on the side or below the electrode body 700, an insulating film that encases the electrode body 700, etc. may be disposed.

The container 100 is a rectangular parallelepiped (angular or box-shaped) case having a container body 110 with an opening and a lid 120 that closes the opening of the container body 110. The container body 110 is a rectangular cylindrical member with a bottom that constitutes the main body of the container 100. The container body 110 has a pair of flat and rectangular short side walls on both sides (short sides) in the X-axis direction, a pair of flat and rectangular long side walls on both sides (long sides) in the Y-axis direction, and a flat and rectangular bottom wall on the negative Z-axis side. The lid 120 is a rectangular plate-shaped member that constitutes the lid of the container 100, and is arranged extending in the X-axis direction on the positive Z-axis side of the container body 110.

With this configuration, the container 100 is structured so that the electrode body 700 and the like are housed inside the container body 110, and then the container body 110 and the lid body 120 are joined by welding or the like, thereby sealing the inside. The material of the container 100 (container body 110 and lid body 120) is not particularly limited, but is preferably a weldable metal such as stainless steel, aluminum, aluminum alloy, iron, or plated steel sheet.

The lid 120 is formed with a through hole 130 and a gas exhaust valve 140. The gas exhaust valve 140 is a safety valve that releases pressure when the pressure inside the container 100 increases. The through hole 130 is a liquid injection port formed in the lid 120 to inject electrolyte into the container 100 during the manufacture of the energy storage element 10. In this embodiment, the through hole 130 is disposed toward the negative X-axis direction of the lid 120 and in the center in the Y-axis direction, but the through hole 130 may be disposed at any position in the lid 120. A detailed description of the configuration around the through hole 130 of the lid 120 will be given later.

The blocking member 200 is a member that blocks the through-hole 130 of the lid 120 of the container 100. Specifically, the blocking member 200 is a liquid injection plug that is joined to the container 100 (lid 120) to block the through-hole 130 after the electrolyte is injected into the container 100 from the through-hole 130 during the manufacture of the energy storage element 10. The material of the blocking member 200 is not particularly limited, but any metal that can be used for the container 100 can be used. In particular, the blocking member 200 is formed of a material that can be welded to the container 100 (lid 120), such as the same material as the container 100 (lid 120). A detailed description of the configuration of the blocking member 200 will be given later.

The electrode body 700 is a 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 positive electrode active material layer is formed on a positive electrode substrate layer that is a long strip-shaped current collector foil made of aluminum or an aluminum alloy. The negative electrode plate is an electrode plate in which a negative electrode active material layer is formed on a negative electrode substrate layer that is a long strip-shaped current collector foil made of copper or a copper alloy. As the positive electrode active material and the negative electrode active material used in the positive electrode active material layer and the negative electrode active material layer, any suitable known material can be used as long as they are active materials capable of absorbing and releasing lithium ions. The separator can be a microporous sheet or nonwoven fabric made of resin.

The electrode body 700 is formed by stacking a positive electrode plate, a negative electrode plate, and a separator. Specifically, the electrode body 700 is formed by winding a separator between the positive electrode plate and the negative electrode plate. More specifically, the electrode body 700 is wound with the positive electrode plate and the negative electrode plate shifted from each other in the direction of the winding axis via the separator. The winding axis is a virtual axis that serves as the central axis when winding the positive electrode plate and the negative electrode plate, and in this embodiment, it is a straight line that passes through the center of the electrode body 700 and is parallel to the X-axis direction. The positive electrode plate and the negative electrode plate have a portion (active material layer non-formed portion) at the end 710 in the shifted direction where the active material is not formed (coated) and the base material layer is exposed. In this embodiment, an oval shape is illustrated as the cross-sectional shape of the electrode body 700, but it may be a circle, an ellipse, a polygon, or the like.

The electrode terminals 300 are terminal members (positive and negative terminals) electrically connected to the electrode body 700 via the current collector 600. In other words, the electrode terminals 300 are metal members for conducting electricity stored in the electrode body 700 to the external space of the energy storage element 10 and for introducing electricity into the internal space of the energy storage element 10 to store electricity in the electrode body 700. The electrode terminals 300 are formed of conductive materials such as metals such as aluminum, aluminum alloy, copper, or copper alloy. The electrode terminals 300 are connected (joined) to the current collector 600 by crimping, welding, or the like, and are attached to the lid body 120.

The upper gasket 400 is a plate-like rectangular member (positive electrode upper gasket and negative electrode upper gasket) that is disposed between the lid 120 of the container 100 and the electrode terminal 300, and insulates and seals between the lid 120 and the electrode terminal 300. The lower gasket 500 is a plate-like rectangular member (positive electrode lower gasket and negative electrode lower gasket) that is disposed between the lid 120 of the container 100 and the current collector 600, and insulates between the lid 120 and the current collector 600. The upper gasket 400 and the lower gasket 500 may be formed of any material that has insulating properties, but are formed of insulating materials such as polypropylene (PP), polyethylene (PE), and polystyrene (PS).

The current collectors 600 are disposed on both sides of the electrode body 700 in the X-axis direction, and are connected (joined) to the end 710 of the electrode body 700 and the electrode terminal 300. They are current collectors (positive and negative current collectors) that have conductivity and rigidity and electrically connect the electrode body 700 and the electrode terminal 300. The current collectors 600 are fixedly connected (joined) to the lid 120. The material of the current collectors 600 is not particularly limited, but for example, the positive electrode side current collector 600 is made of aluminum or an aluminum alloy, etc., like the positive electrode substrate layer of the electrode body 700, and the negative electrode side current collector 600 is made of copper or a copper alloy, etc., like the negative electrode substrate layer of the electrode body 700.

[2. Description of the Surroundings of the Through-hole 130 of the Lid 120 and the Closing Member 200]
Next, the configuration around the through hole 130 of the lid 120 and the configuration of the blocking member 200 will be described in detail. FIG. 3 is a perspective view and a cross-sectional view showing the configuration around the through hole 130 of the lid 120 and the blocking member 200 according to this embodiment. Specifically, FIG. 3A is an enlarged perspective view showing the periphery of the through hole 130 of the lid 120 and the blocking member 200 shown in FIG. 2. FIG. 3B is a cross-sectional view showing a cross section of the configuration of FIG. 3A cut along a plane including the central axis of the through hole 130 and parallel to the XZ plane. FIG. 4 is a cross-sectional view showing a configuration in which the blocking member 200 is joined to the lid 120 according to this embodiment. Specifically, FIG. 4A shows a state in which the blocking member 200 is attached to the lid 120, and FIG. 4B shows a state in which the blocking member 200 is joined to the lid 120.

As shown in these figures, the through hole 130 is a circular through hole (pouring hole) that penetrates the lid body 120 in the Z-axis direction (when viewed from above), and the electrolyte is poured into the container 100 through the through hole 130. A first container recess 131 is formed around the through hole 130. The first container recess 131 is a ring-shaped recess as viewed from the Z-axis direction, recessed in the negative Z-axis direction from the outer surface 121 of the lid body 120 in the positive Z-axis direction so as to surround the periphery of the through hole 130. In other words, the outer surface 121 of the lid body 120 is recessed to form the first container recess 131, and the through hole 130 is formed inside the first container recess 131 and in the center of the first container recess 131 as viewed from the Z-axis direction.

The blocking member 200 is a member (liquid injection plug) that is joined to the lid 120 by welding while blocking the through hole 130. The blocking member 200 has a main body portion 210 and a shaft portion 220.

The main body 210 is disposed in the Z-axis positive direction of the through hole 130 and the container first recess 131, and is the main body of the blocking member 200 that covers the through hole 130 and the container first recess 131. The main body 210 is a circular (disk-shaped) portion (flange portion) located on the Z-axis positive side of the blocking member 200 when viewed from the Z-axis direction, and is joined to the lid 120 in a state where it covers the entire through hole 130 and the container first recess 131. The main body 210 is provided with a blocking member first recess 211, a blocking member second recess 212, and a blocking member outer periphery 213.

The blocking member first recess 211 is located at the center of the outer surface (surface facing the positive Z-axis direction) of the main body 210, and is a generally conical recess recessed toward the negative Z-axis direction. The blocking member first recess 211 is used, for example, as a marker when joining the blocking member 200 to the lid 120. In other words, the blocking member first recess 211 allows the position of the blocking member 200 to be grasped, so that the blocking member 200 can be placed at an accurate position on the lid 120 and joined to the lid 120.

The blocking member second recess 212 is an annular recess as viewed from the Z-axis direction, with the surface of the body 210 facing the negative Z-axis recessed in the positive Z-axis direction so as to surround the periphery of the shaft 220. The blocking member second recess 212 is a recess whose cross-sectional shape is rectangular over its entire circumference when cut along a plane including the central axis of the through hole 130. The blocking member second recess 212 has an inner circumference larger than the through hole 130 as viewed from the Z-axis direction, is disposed within the container first recess 131, and has an outer circumference larger than the container first recess 131.

The blocking member outer peripheral portion 213 is a ring-shaped convex portion when viewed from the Z-axis direction, with the outer peripheral portion including the outer edge of the main body portion 210 protruding in the negative Z-axis direction so as to surround the periphery of the blocking member second recess 212. The blocking member outer peripheral portion 213 is a convex portion whose cross-sectional shape is rectangular when cut along a plane including the central axis of the through hole 130 over its entire circumference.

The shaft portion 220 is a protruding portion formed to protrude from the main body portion 210 of the blocking member 200 and inserted into the through hole 130 of the lid body 120. The shaft portion 220 is a cylindrical portion that is located at the center position of the main body portion 210 when viewed from the Z axis direction and extends from the center position in the negative Z axis direction. The shaft portion 220 has a pillar portion 221 that is located in the negative Z axis direction of the blocking member first recess 211, a reduced diameter portion 222 that gradually reduces in diameter from the pillar portion 221 in the negative Z axis direction, and a tip portion 223 that extends from the reduced diameter portion 222 in the negative Z axis direction.

The pillar portion 221 is a cylindrical portion located on the Z-axis positive side of the shaft portion 220. When viewed from the Z-axis direction, the pillar portion 221 has an outer peripheral shape that is approximately the same as the inner peripheral shape of the through-hole 130. The reduced diameter portion 222 is a truncated cone-shaped portion whose diameter gradually decreases from the end of the pillar portion 221 in the Z-axis negative direction toward the Z-axis negative direction in a cross-sectional shape cut on the XZ plane. The tip portion 223 is a cylindrical portion that extends from the end of the reduced diameter portion 222 in the Z-axis negative direction toward the Z-axis negative direction, and is the tip portion of the shaft portion 220. In this way, the shaft portion 220 has a shape with a tapered tip portion so that it can be easily inserted into the through-hole 130 of the lid body 120.

In this configuration, when the blocking member 200 is joined to the lid body 120, as shown in FIG. 4(a), the shaft portion 220 of the blocking member 200 is inserted (pressed) into the through hole 130 of the lid body 120 and engaged with the through hole 130. In addition, the blocking member outer peripheral portion 213 of the main body portion 210 of the blocking member 200 is placed on the outer surface 121 of the lid body 120 while overlapping and abutting the outer surface 121. As a result, a first space S1 is formed between the blocking member second recess 212 and the outer surface 121, and a second space S2 is formed between the blocking member second recess 212 and the container first recess 131.

The first space S1 is an annular space when viewed from the Z-axis direction, and is disposed adjacent to the blocking member outer peripheral portion 213 on the through-hole 130 side of the blocking member outer peripheral portion 213. The second space S2 is an annular space when viewed from the Z-axis direction, and is disposed connected to the first space S1 on the through-hole 130 side of the first space S1. In other words, the second space S2 is a space disposed inside the first space S1 and outside the shaft portion 220 (pillar portion 221), between the blocking member second recess 212 and the container first recess 131.

In this way, the first space S1 and the second space S2 are formed by at least one of the container 100 and the blocking member 200 being recessed. That is, the first space S1 is formed by the blocking member 200 being recessed (the blocking member second recess 212 is formed). The second space S2 is formed by the container 100 being recessed (the container first recess 131 is formed) and the blocking member 200 being recessed (the blocking member second recess 212 is formed). As a result, the second space S2 has a larger volume than the first space S1. That is, the second space S2 is formed to have a larger volume (capacity) by being deeper (higher in the Z-axis direction) than the first space S1.

4B, the outer peripheral portion 213 of the main body 210 of the blocking member 200, which is overlapped with the lid 120 in the Z-axis direction, is joined to the outer surface 121 of the lid 120 over the entire circumference. Specifically, laser light L is irradiated from the positive direction of the Z-axis toward the blocking member outer peripheral portion 213, and the blocking member outer peripheral portion 213 and the outer surface 121 are laser-welded to form a laser welded portion 150 that is annular when viewed from the Z-axis direction. In other words, the container 100 and the blocking member 200 are overlapped and arranged in the penetration direction (Z-axis direction) of the through hole 130, and the overlapped portion is formed with the laser welded portion 150 in which the container 100 and the blocking member 200 are joined by laser welding. The laser welded portion 150 is a molten portion in which the blocking member outer peripheral portion 213 and the portion on the outer surface 121 side of the lid 120 are melted by laser welding.

In this way, the entire outer periphery 213 of the blocking member melts to become the laser weld 150, and a space (first space S1 and second space S2) is formed between the container 100 and the blocking member 200, extending from the laser weld 150 toward the through hole 130. In other words, the first space S1 is a space that is located adjacent to the laser weld 150 on the through hole 130 side of the laser weld 150.

[3. Description of Effects]
As described above, according to the energy storage element 10 according to the embodiment of the present invention, the container 100 and the blocking member 200 are arranged in a stacked manner in the penetration direction (Z-axis direction) of the through hole 130 of the container 100, and the laser welded portion 150 is formed in the stacked portion. A space (first space S1 and second space S2) extending from the laser welded portion 150 toward the through hole 130 is formed between the container 100 and the blocking member 200. Here, if a space extending from the laser welding target portion of the container 100 and the blocking member 200 toward the through hole 130 is formed during laser welding, the gas generated during laser welding escapes into the space, so that the occurrence of pinholes can be suppressed. In other words, if a space extending from the laser welded portion 150 toward the through hole 130 is formed between the container 100 and the blocking member 200, it can be seen that a space extending from the laser welding target portion of the container 100 and the blocking member 200 toward the through hole 130 is formed during laser welding. This allows gas generated during laser welding to escape into the space, thereby suppressing the occurrence of pinholes, thereby realizing an energy storage element 10 with improved bonding quality between the container 100 and the blocking member 200.

A first space S1 is arranged on the through hole 130 side of the laser welded portion 150, and a second space S2, which has a larger volume than the first space S1, is arranged on the through hole 130 side of the first space S1, so that gas generated in the laser welded portion 150 escapes to the first space S1 and then to the second space S2. This allows the gas generated in the laser welded portion 150 to escape effectively, improving the joining quality of the container 100 and the closure member 200.

By recessing at least one of the container 100 and the blocking member 200, the space can be easily formed. This makes it easy to improve the bonding quality of the container 100 and the blocking member 200. In particular, in this embodiment, the first space S1 is formed by recessing the blocking member 200. Therefore, the first space S1 can be formed without recessing the container 100 (for example, by utilizing the shape of the existing container 100).

[4. Description of Modifications]
(Variation 1)
Next, a first modification of the above embodiment will be described. Fig. 5 is a cross-sectional view showing the configuration of the periphery of the through hole 130 of the lid 120 and the blocking member 201 according to the first modification of the present embodiment. Specifically, Fig. 5 shows the configuration in which the blocking member 201 is joined to the lid 120, and corresponds to Fig. 4.

As shown in FIG. 5, the blocking member 201 in this modified example has a blocking member second recess 214 formed in the main body 210 instead of the blocking member second recess 212 formed in the main body 210 of the blocking member 200 in the above embodiment. The rest of the configuration of this modified example is the same as in the above embodiment, so detailed description will be omitted.

The blocking member second recess 214 is different from the blocking member second recess 212 in the above embodiment, and is a circular recess as viewed from the Z-axis direction, with the surface of the body 210 facing the negative Z-axis being curved in the positive Z-axis direction. In other words, the blocking member second recess 214 has a curved shape (approximately arc shape) around its entire circumference, with the outer edge shape when cut along a plane including the central axis of the through hole 130 becoming narrower in the positive Z-axis direction.

In this configuration, as in the above embodiment, a first space S3 is formed between the blocking member second recess 214 and the outer surface 121, and a second space S4 is formed between the blocking member second recess 214 and the container first recess 131. The first space S3 is an annular space as viewed from the Z-axis direction, disposed adjacent to the blocking member outer peripheral portion 213 on the through hole 130 side of the blocking member outer peripheral portion 213. The second space S4 is an annular space as viewed from the Z-axis direction, disposed connected to the first space S3 on the through hole 130 side of the first space S3. Then, the blocking member outer peripheral portion 213 of the blocking member 201 and the outer surface 121 of the lid body 120 are laser welded to form the laser welded portion 150. As a result, the first space S3 becomes a space disposed adjacent to the laser welded portion 150 on the through hole 130 side of the laser welded portion 150.

As described above, the energy storage element according to this modified example can achieve the same effect as the above embodiment. The shape of the blocking member second recess 214 is not limited to the cross section having a substantially arc shape as shown in FIG. 5, and the cross section may have any shape, such as a part of an oval shape, a part of an ellipse shape, or a polygonal shape other than a rectangular shape, such as a triangular shape.

(Variation 2)
Next, a second modification of the above embodiment will be described. Fig. 6 is a cross-sectional view showing the configuration of the periphery of the through-hole 130 of the lid 120 and the closing member 202 according to the second modification of the present embodiment. Specifically, Fig. 6 shows the configuration in which the closing member 202 is joined to the lid 120, and corresponds to Fig. 4 .

As shown in FIG. 6, the blocking member 202 in this modified example has a protrusion 215 formed on the main body 210, so that a space (first space S5 and second space S2) is formed between the blocking member 202 and the lid 120. The rest of the configuration of this modified example is the same as in the above embodiment, so a detailed description will be omitted.

The protrusion 215 is a protrusion that protrudes in the negative Z-axis direction from the surface of the body 210 of the blocking member 202 in the negative Z-axis direction toward the outer surface 121 of the lid 120 and abuts against the outer surface 121, and is disposed in the first space S5 between the body 210 and the outer surface 121. The protrusion 215 is a cone-shaped protrusion whose cross-sectional shape when cut along a plane including the central axis of the through hole 130 is triangular, and multiple protrusions 215 are disposed in a ring shape at intervals (for example, four protrusions 215 are equally spaced) along the outer periphery of the body 210. The number and arrangement of the protrusions 215 are not particularly limited. The protrusion 215 may be a single protrusion that is continuously formed along the outer periphery of the body 210 and has a ring shape when viewed from the Z-axis direction.

In this configuration, the blocking member outer periphery 216 of the main body 210 of the blocking member 202 and the outer surface 121 of the lid 120 are spaced apart from each other, but the entire circumference of the blocking member outer periphery 216 is laser welded to the outer surface 121 to form a ring-shaped laser weld 160 as viewed from the Z-axis direction. As a result, the first space S5 is a ring-shaped space as viewed from the Z-axis direction that is located between the main body 210 and the outer surface 121 and adjacent to the laser weld 160 on the through hole 130 side of the laser weld 160.

As described above, the energy storage element according to this modification can achieve the same effect as the above embodiment. In this modification, instead of the blocking member 202 having the protrusion 215, the lid 120 may have a protrusion. In other words, at least one of the container 100 (lid 120) and the blocking member 202 may have a protrusion that protrudes toward the other and abuts against the other, and is disposed within the space (first space S5). In this way, by providing at least one of the container 100 and the blocking member 202 with a protrusion that abuts against the other, the above space is formed by the protrusion, and therefore the above space can be easily formed. This makes it easy to improve the joining quality of the container 100 and the blocking member 202.

(Variation 3)
Next, a third modification of the above embodiment will be described. Fig. 7 is a perspective view and a cross-sectional view showing the configuration of the periphery of the through-hole 130 of the lid 120a and the blocking member 203 according to the third modification of the present embodiment. Fig. 8 is a cross-sectional view showing the configuration in which the blocking member 203 is joined to the lid 120a according to the third modification of the present embodiment. Specifically, Figs. 7 and 8 correspond to Figs. 3 and 4.

7 and 8, in this modified example, the container 100 has a lid 120a, and in addition to the first container recess 131, the second container recess 132 is formed in the lid 120a around the through hole 130. Also, in this modified example, the blocking member 203 does not have the second blocking member recess 212 formed in the main body 210 of the blocking member 200 in the above embodiment formed in the main body 210. Therefore, the blocking member outer periphery 213 is not a convex portion as in the above embodiment, but is the outer periphery of the flat main body 210. The other configurations of this modified example are the same as those of the above embodiment, so detailed description will be omitted.

The second container recess 132 is a circular recess as viewed from the Z-axis direction, recessed from the outer surface 121 of the lid body 120a in the positive Z-axis direction in the negative Z-axis direction so as to surround the periphery of the first container recess 131. The outer periphery of the second container recess 132 as viewed from the Z-axis direction is smaller than the outer edge of the main body 210 of the blocking member 203. In other words, the outer surface 121 of the lid body 120a is recessed to form the second container recess 132, and the first container recess 131 is formed inside the second container recess 132 and at the center of the second container recess 132 as viewed from the Z-axis direction. A through hole 130 is formed inside the first container recess 131 and at the center of the first container recess 131 as viewed from the Z-axis direction.

In this configuration, when the blocking member 203 is joined to the lid body 120a, as shown in FIG. 8(a), the blocking member outer periphery 213 of the main body 210 of the blocking member 203 is placed on the outer surface 121 of the lid body 120a while overlapping and abutting the outer surface 121. As a result, a first space S6 is formed between the main body 210 and the second container recess 132, and a second space S7 is formed between the main body 210 and the first container recess 131.

8B, the entire circumference of the blocking member outer periphery 213 of the main body 210 of the blocking member 203 and the outer surface 121 of the lid 120a are laser welded to form the laser welded portion 150. As a result, the first space S6 is disposed between the blocking member 203 and the lid 120a, and is disposed adjacent to the laser welded portion 150 on the through hole 130 side of the laser welded portion 150, and is an annular space as viewed from the Z axis direction. The second space S7 is disposed on the through hole 130 side of the first space S6, connected to the first space S6, and is an annular space as viewed from the Z axis direction. In other words, the entire blocking member outer periphery 213 melts to form the laser welded portion 150, and therefore spaces (first space S6 and second space S7) extending from the laser welded portion 150 toward the through hole 130 are formed between the lid 120a and the blocking member 203.

In this way, the first space S6 and the second space S7 are formed by the container 100 (lid body 120a) being recessed. In other words, the first space S6 and the second space S7 are formed by the lid body 120a being recessed (the container second recess 132 and the container first recess 131 are formed). As a result, the second space S7 is formed to be deeper (higher in the Z-axis direction) than the first space S6, and therefore has a larger volume (capacity).

As described above, the energy storage element according to this modified example can achieve the same effects as the above-described embodiment. In particular, in this modified example, the spaces (first space S6 and second space S7) are formed by recessing the container 100 (lid 120a), and therefore the spaces can be easily formed. In other words, since recessing the lid 120a is easier than processing the blocking member 203 into a complex shape with a recess, the spaces can be easily formed. This makes it easy to improve the bonding quality between the container 100 and the blocking member 203.

In addition, in this modified example, blocking member 203 may be replaced by blocking member 200 of the above embodiment, blocking member 201 of modified example 1, or blocking member 202 of modified example 2.

(Variation 4)
Next, a fourth modification of the above embodiment will be described. Fig. 9 is a cross-sectional view showing the configuration of the periphery of the through-hole 130 of the lid 120 and the blocking member 204 according to the fourth modification of the present embodiment. Specifically, Fig. 9 shows a state in which the blocking member 204 is joined to the lid 120, and corresponds to (b) of Fig. 4.

As shown in FIG. 9, the blocking member 204 in this modified example has a notch 224 formed in the shaft portion 220. The rest of the configuration of this modified example is the same as in the above embodiment, so a detailed description will be omitted.

The notch 224 is a notched portion formed in the side surface of the shaft portion 220 (the column portion 221) in the negative X-axis direction. In other words, by forming the notch 224, the side surface of the shaft portion 220 in the negative X-axis direction is formed, for example, in a flat shape. As a result, a gap S8 is formed between the side surface of the shaft portion 220 in the negative X-axis direction and the inner surface of the through-hole 130 in the negative X-axis direction, which penetrates the lid body 120 and connects to the second space S2. In this way, a gap S8 is formed between the shaft portion 220 and the inner surface of the through-hole 130, which is connected to the space (second space S2) and penetrates the container 100 (lid body 120).

As described above, the energy storage element according to this modified example can achieve the same effects as the above-mentioned embodiment. In particular, in this modified example, a gap S8 that connects to the above-mentioned space (second space S2) is formed between the shaft portion 220 of the blocking member 204 and the inner surface of the through hole 130 of the container 100, so that gas generated at the laser welded portion 150 can escape to the inside of the container 100 through the gap S8. This allows the gas generated at the laser welded portion 150 to escape effectively, thereby improving the joining quality of the container 100 and the blocking member 204.

In this modified example, the notch 224 may be a notch of any shape, and may be formed on any side surface of the shaft portion 220, such as the side surface of the shaft portion 220 in the positive direction of the X-axis. The entire circumference of the shaft portion 220 may be cut out to form an annular gap, as viewed from the Z-axis direction, between the entire circumference of the shaft portion 220 and the inner surface of the through-hole 130, which penetrates the cover body 120 and connects to the second space S2. In the configurations of modified examples 1 to 3 above, the notch 224 may be formed in the blocking members 201 to 203.

(Other Modifications)
Although the energy storage element according to the embodiment of the present invention (including its modified examples, the same applies below) has been described above, the present invention is not limited to this embodiment. The embodiment disclosed here is illustrative in all respects, and the scope of the present invention includes all modifications within the meaning and scope equivalent to the claims.

For example, in the above embodiment, the through hole 130 is formed in the lid of the container 100, and the closing member is joined to the lid. However, the through hole 130 may be formed in the container body 110 of the container 100, and the closing member may be joined to the container body 110.

In the above embodiment, the through hole 130 is a liquid injection port for injecting the electrolyte, and the blocking member is a liquid injection plug. However, the through hole 130 is not limited to a liquid injection port, but may be any through hole formed in the container 100, and the blocking member is not limited to a liquid injection plug, but may be any member that blocks the through hole 130. For example, the through hole 130 may be a through hole formed in the center of the lid, and the blocking member may block the through hole 130 to form the gas exhaust valve 140.

In the above embodiment, the outer periphery of the closure member (outer periphery of the closure member) is laser welded to the container 100 to form the laser weld. However, a portion of the closure member that is inside the outer periphery may be laser welded to the container 100 to form the laser weld. Even in this case, it is sufficient that a space is formed between the container 100 and the closure member, extending from the laser weld toward the through hole 130.

In the above embodiment, the second space has a larger volume (capacity) than the first space, but the second space may have the same volume as the first space, or may have a smaller volume than the first space.

In the above embodiment, the first container recess 131 is formed around the through hole 130. However, the first container recess 131 does not have to be formed around the through hole 130. In other words, the second space is not formed between the container 100 and the closing member, and the first space may extend from the laser welded portion toward the through hole 130.

In the above embodiment, the blocking member has an axis portion 220 that is inserted into the through hole 130. However, the blocking member may not have an axis portion 220, and the through hole 130 may be blocked by joining the main body portion 210 to the container 100. The main body portion 210 of the blocking member may not have the first blocking member recess 211.

In the above embodiment, the above configuration (laser welds are formed, and a space is formed between the container 100 and the closing member extending from the laser welds toward the through hole 130, etc.) is applied around the entire circumference of the through hole 130. However, the above configuration may not be applied to a part of the circumference of the through hole 130. In other words, a laser weld may not be formed in a part of the circumference of the through hole 130, a space may not be formed extending from the laser welds toward the through hole 130, and other configurations described above may not be present.

In the above embodiment, the electrode body 700 is a so-called vertically wound electrode body in which the winding axis is parallel to the cover body. However, the electrode body 700 may be a so-called horizontally wound electrode body in which the winding axis is perpendicular to the cover body. The shape of the electrode body 700 is not limited to a wound type, and may be a stack type in which flat electrode plates are stacked, or a shape in which the electrode plates and/or separators are folded in a bellows shape (a form in which the separator is bellows-shaped and a rectangular electrode plate is sandwiched between it, a form in which the electrode plate and the separator are stacked and then made into a bellows shape, etc.). In these cases, the end 710 may be a tab protruding from the main body of the electrode body 700.

Any combination of the components included in the above embodiment and its variations is also within the scope of the present invention.

The present invention can be realized not only as such an energy storage element, but also as a combination of a container and a closing member.

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

REFERENCE SIGNS LIST 10 Energy storage element 100 Container 110 Container body 120, 120a Lid 121 Outer surface 130 Through hole 131 Container first recess 132 Container second recess 150, 160 Laser welded portion 200, 201, 202, 203, 204 Closing member 210 Main body 211 Closing member first recess 212, 214 Closing member second recess 213, 216 Closing member outer periphery 215 Protrusion 220 Shaft 224 Notch 300 Electrode terminal 600 Current collector 700 Electrode body S1, S3, S5, S6 First space S2, S4, S7 Second space S8 Gap

Claims (4)

A container having a through hole formed therein;
a closing member joined to the container to close the through hole,
the container and the closing member are arranged in a stacked manner in a penetration direction of the through hole, and a laser welded portion is formed at the stacked portion by joining the container and the closing member by laser welding,
a space is formed between the container and the closing member, the space extending from the laser welded portion toward the through hole;
The blocking member has a shaft portion that is inserted into the through hole,
The space is
a first space arranged adjacent to the laser weld on the through hole side of the laser weld;
a second space that is connected to the first space and arranged on the through hole side of the first space, the second space having a larger volume than the first space. A container having a through hole formed therein;
a closing member joined to the container to close the through hole,
the container and the closing member are arranged in a stacked manner in a penetration direction of the through hole, and a laser welded portion is formed at the stacked portion by joining the container and the closing member by laser welding,
a space is formed between the container and the closing member, the space extending from the laser welded portion toward the through hole;
The blocking member has a shaft portion that is inserted into the through hole,
the space is formed by recessing both the periphery of the through hole in the container and the closing member . The energy storage element according to claim 1 , wherein a gap that is connected to the space and that passes through the container is formed between the shaft portion and an inner surface of the through hole. The energy storage element according to any one of claims 1 to 3, wherein at least one of the container and the closing member has a protrusion that protrudes toward the other and abuts against the other, the protrusion being disposed within the space.

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