WO2024219402A1 - Power storage element and method for producing same - Google Patents

Abstract

This power storage element includes a container. The container has a long wall portion in a first direction. The wall portion has a gas discharge valve, a first protrusion, and a second protrusion. The gas discharge valve is a part having a thickness smaller than those of other parts of the wall portion. The first protrusion is disposed in a first direction of the gas discharge valve. The second protrusion is disposed in a second direction, of the gas discharge valve, orthogonal to the first direction. The width of the second protrusion in the second direction is larger than the width of the first protrusion in the first direction.

Description

Electric storage element and manufacturing method thereof

The present invention relates to an energy storage element and a method for manufacturing the same.

Patent Document 1 discloses a sealing plate for use in sealed batteries such as lithium ion batteries. This sealing plate employs a configuration in which a base material portion of the sealing plate is provided near a valve portion formed into a thin film, and a protrusion is formed on the outside of the base material portion that is filled with excess material from the molding of the valve portion.

Patent No. 5198723

The conventional sealing plate is a plate-like member that is elongated in one direction. Therefore, the sealing plate is easily bent in the longitudinal direction. In this regard, in the conventional sealing plate, the protrusion provided near the valve portion surrounds the entire circumference of the valve portion when viewed from the protruding direction of the protrusion, and has a uniform width in the circumferential direction of the valve portion. Therefore, from the viewpoint of protecting the valve portion from stress caused by bending the sealing plate in the longitudinal direction, it is conceivable that the width of at least a portion of the protrusion in the circumferential direction (width in the direction perpendicular to the circumferential direction) may not be sufficient.

The present invention was made by the inventors by focusing on the above problem, and aims to provide an energy storage element that can protect the gas release valve and a method for manufacturing the same.

The energy storage element according to one embodiment of the present invention is an energy storage element including a container, the container including a wall portion that is elongated in a first direction, the wall portion including a gas exhaust valve, a first convex portion, and a second convex portion, the gas exhaust valve being a portion having a smaller thickness than other portions of the wall portion, the first convex portion being disposed in the first direction of the gas exhaust valve, the second convex portion being disposed in a second direction of the gas exhaust valve that is perpendicular to the first direction, and the width of the second convex portion in the second direction being greater than the width of the first convex portion in the first direction.

A manufacturing method of an energy storage element according to one aspect of the present invention is a manufacturing method of an energy storage element including a container, the container including a wall portion that is elongated in a first direction, the manufacturing method including forming the wall portion by pressing a metal plate that is a base material of the wall portion, the forming of the wall portion including forming a gas exhaust valve that is a portion of the wall portion that is thinner than other portions, and forming a first convex portion and a second convex portion with metal that escapes outward from the position of the gas exhaust valve when forming the gas exhaust valve, the forming of the first convex portion and the second convex portion including forming the first convex portion in the first direction of the gas exhaust valve and forming the second convex portion in a second direction of the gas exhaust valve that is perpendicular to the first direction, and the width of the second convex portion in the second direction is greater than the width of the first convex portion in the first direction.

The present invention provides a storage element that can protect the gas exhaust valve.

FIG. 1 is a perspective view showing the appearance of an energy storage device according to an embodiment. FIG. 2 is a perspective view showing components arranged inside a container of the energy storage device according to the embodiment. FIG. 3 is an exploded perspective view of the energy storage device according to the embodiment. FIG. 4 is a perspective view showing the configuration of the gas exhaust valve and its surroundings according to the embodiment. FIG. 5 is a plan view showing the configuration of the gas exhaust valve and its surroundings according to the embodiment. FIG. 6 is a first cross-sectional view showing the configuration of the gas release valve and its surroundings according to the embodiment. FIG. 7 is a second cross-sectional view showing the configuration of the gas release valve and its surroundings according to the embodiment. FIG. 8 is a plan view showing a configuration of a gas release valve and its periphery according to the first modification of the embodiment. FIG. 9 is a first cross-sectional view showing a configuration of a gas release valve and its surroundings according to the first modification of the embodiment. FIG. 10 is a second cross-sectional view showing the configuration of the gas release valve and its periphery according to the first modification of the embodiment. FIG. 11 is a plan view showing a configuration of a gas release valve and its periphery according to the second modification of the embodiment. FIG. 12 is a first cross-sectional view showing a configuration of a gas release valve and its surroundings according to the second modification of the embodiment. FIG. 13 is a second cross-sectional view showing the configuration of the gas release valve and its periphery according to the second modification of the embodiment. FIG. 14 is a plan view illustrating a schematic configuration of an energy storage device including an energy storage element according to an embodiment.

(1) An energy storage element according to one embodiment of the present invention is an energy storage element including a container, the container including a wall portion that is elongated in a first direction, the wall portion including a gas exhaust valve, a first convex portion, and a second convex portion, the gas exhaust valve being a portion having a smaller thickness than other portions of the wall portion, the first convex portion being disposed in the first direction of the gas exhaust valve, the second convex portion being disposed in a second direction of the gas exhaust valve that is perpendicular to the first direction, and the width of the second convex portion in the second direction being greater than the width of the first convex portion in the first direction.

In the energy storage element according to one aspect of the present invention, the gas exhaust valve is protected by a first convex portion arranged in a first direction and a second convex portion arranged in a second direction. The width of the second convex portion in the second direction is greater than the width of the first convex portion in the first direction. Therefore, the second convex portion more reliably improves the resistance to bending in the longitudinal direction (first direction) of the wall portion in the portion including the gas exhaust valve. As a result, when an external force acts on the wall portion during the manufacture or use of the energy storage element, deformation of the gas exhaust valve due to the external force is suppressed. In other words, the gas exhaust valve is protected.

(2) In the energy storage element described in (1) above, the first convex portion may be disposed on one side and the other side of the gas exhaust valve in the first direction, and the second convex portion may be disposed on one side and the other side of the gas exhaust valve in the second direction.

In the energy storage element described in (2) above, the gas release valve is disposed between the first convex portions located on both sides in the first direction and between the second convex portions located on both sides in the second direction. This ensures that the gas release valve is protected more reliably during the manufacture or use of the energy storage element.

(3) In the energy storage element described in (1) or (2) above, when viewed from a third direction perpendicular to the first direction and the second direction, the wall portion may be formed with a series of protrusions that include the first convex portion and the second convex portion and surround the gas release valve.

In the energy storage element described in (3) above, the gas exhaust valve is entirely surrounded by the protrusion when viewed from the third direction. Therefore, the energy storage element is reliably protected by the gas exhaust valve during manufacture or use.

(4) In the energy storage element described in any one of (1) to (3) above, the second convex portion and the gas exhaust valve may be arranged continuously in the second direction in the wall portion.

In the energy storage element described in (4) above, the second convex portion and the gas exhaust valve are arranged in series, simplifying the shape of the gas exhaust valve and its surroundings in the wall of the container.

(5) The energy storage element described in any one of (1) to (3) above may have an intermediate portion between the second convex portion and the gas exhaust valve in the wall portion, the intermediate portion having a thickness greater than that of the gas exhaust valve.

In the energy storage element described in (5) above, the shape of the second convex portion when viewed from the thickness direction (third direction) of the wall portion and the shape of the gas exhaust valve are independent of each other. Therefore, the shape of the second convex portion can be determined independently of the shape of the gas exhaust valve. Alternatively, the shape of the gas exhaust valve can be determined independently of the shape of the second convex portion.

(6) A method for manufacturing an energy storage element according to one embodiment of the present invention is a method for manufacturing an energy storage element including a container, the container including a wall portion that is elongated in a first direction, the method including forming the wall portion by pressing a metal plate that is a base material of the wall portion, the forming of the wall portion including forming a gas exhaust valve that is a portion of the wall portion that is thinner than other portions, and forming a first convex portion and a second convex portion with metal that escapes outward from the position of the gas exhaust valve when forming the gas exhaust valve, the forming of the first convex portion and the second convex portion including forming the first convex portion in the first direction of the gas exhaust valve and forming a second convex portion in a second direction of the gas exhaust valve that is perpendicular to the first direction, and the width of the second convex portion in the second direction is greater than the width of the first convex portion in the first direction.

According to the manufacturing method of the energy storage element described in (6) above, when the wall portion is formed by press working, the first convex portion and the second convex portion are formed so that the width of the second convex portion is larger than the width of the first convex portion. The first convex portion is disposed in the longitudinal direction (first direction) of the wall portion of the gas exhaust valve, and the second convex portion is disposed in the second direction of the gas exhaust valve.

Below, with reference to the drawings, an explanation will be given of an energy storage element according to an embodiment of the present invention. The embodiments explained below are all comprehensive or specific examples. The numerical values, shapes, materials, components, the arrangement and connection of the components, manufacturing processes, and the order of the manufacturing processes shown in the following embodiments are merely examples and are not intended to limit the present invention. In each figure, the dimensions are not strictly shown. Furthermore, in each figure, the same or similar components are given the same reference numerals.

In the following explanation and drawings, the X-axis direction is defined as the direction in which a pair of terminals (positive and negative, hereinafter the same) of the energy storage element are arranged, the direction in which a pair of current collectors are arranged, or the direction in which a pair of short sides of the container face each other. The Y-axis direction is defined as the direction in which a pair of long sides of the container face each other, the stacking direction of the electrode plates of the electrode body, or the thickness direction of the container. The Z-axis direction is defined as the direction in which the container body and cover plate of the energy storage element are arranged, or the longitudinal direction of the short sides of the container. These X-axis, Y-axis, and Z-axis directions intersect with each other (orthogonal in this embodiment). Depending on the mode of use, it is possible that the Z-axis direction is not the up-down direction, but for ease of explanation, the following explanation will be given assuming that the Z-axis direction is the up-down direction.

In the following explanation, the positive X-axis direction refers to the direction of the arrow on the X-axis, 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. When simply referring to the "X-axis direction," it means either or both directions parallel to the X-axis. The same applies to terms related to the Y-axis and Z-axis.

Furthermore, expressions indicating a relative direction or attitude, such as parallel and perpendicular, also include cases where the direction or attitude is not strictly the same. Two directions being perpendicular to each other does not only mean that the two directions are completely perpendicular to each other, but also means that the two directions are substantially perpendicular to each other, that is, that the difference between the directions is, for example, about a few percent. In the following description, the term "insulation" means "electrical insulation". The insulating material is preferably formed from a material having a volume resistivity of 1×10 ¹⁰ Ωm or more.

(Embodiment)
[1. General Description of Energy Storage Element 10]
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 embodiment. Figure 2 is a perspective view showing components arranged inside a container 100 of an energy storage element 10 according to the embodiment. Specifically, Figure 2 is a perspective view showing a state in which a container body 110 is separated from the energy storage element 10. Figure 3 is an exploded perspective view of an energy storage element 10 according to the embodiment. Specifically, Figure 3 is a perspective view showing an exploded view of components other than the container body 110 shown in Figure 2.

The energy storage element 10 is a secondary battery, and more 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 the engine of a moving body such as an automobile, a motorcycle, a watercraft, a ship, a snowmobile, an agricultural machine, a construction machine, an automatic guided vehicle (AGV), or a railway vehicle for an electric railway. Examples of the above-mentioned automobiles include electric vehicles (EVs), hybrid electric vehicles (HEVs), plug-in hybrid electric vehicles (PHEVs), and fossil fuel (gasoline, diesel, liquefied natural gas, etc.) vehicles. Examples of the above-mentioned railway vehicles for an electric railway include electric trains, monorails, linear motor cars, and hybrid electric trains 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 or business use.

The energy storage element 10 is not limited to a non-aqueous electrolyte secondary battery, but may be a secondary battery other than a non-aqueous electrolyte secondary battery, or may be a capacitor. The energy storage element 10 may be a primary battery.

As shown in FIG. 1, the energy storage element 10 comprises a container 100, a pair of terminals 130 (positive and negative electrodes), and a pair of upper insulating members 140. As shown in FIGS. 2 and 3, the container 100 contains a pair of lower insulating members 150, an electrode body 400, and a pair of current collectors 500. An electrolyte (non-aqueous electrolyte) is sealed inside the container 100, but is not shown. There are no particular restrictions on the type of electrolyte as long as it does not impair the performance of the energy storage element 10, and various types can be selected. Furthermore, spacers (not shown) may be placed inside the container 100.

The container 100 is a rectangular parallelepiped (box-shaped) case. The container 100 comprises a container body 110 and a cover plate 120. After the electrode body 400 and the like are housed inside the container body 110, the container body 110 and the cover plate 120 are welded together or otherwise joined together to seal the inside of the container 100. There are no particular limitations on the materials used for the container body 110 and the cover plate 120, but it is preferable that they are weldable metals such as stainless steel, aluminum, aluminum alloy, iron, and plated steel sheet.

The container body 110 is a rectangular cylindrical member with a bottom, and an opening 119 is formed at the top. The container body 110 has first side wall portions 111 in both the positive and negative directions of the X axis, and second side wall portions 112 in both the positive and negative directions of the Y axis. The container body 110 has a bottom wall portion 113 in the negative direction of the Z axis. The first side wall portion 111 is a wall portion that forms the short side surface 111a of the container 100, and the second side wall portion 112 is a wall portion that forms the long side surface 112a of the container 100.

The cover plate 120 is a rectangular plate-like member that closes the opening 119 of the container body 110. The cover plate 120 is an example of a wall portion provided in the container 100. The cover plate 120 is elongated in the opposing direction of a pair of short sides 111a of the container body 110. In this embodiment, the longitudinal direction of the cover plate 120 is parallel to the X-axis direction, and the thickness direction of the cover plate 120 is parallel to the Z-axis direction. The outer surface 120b (the surface in the Z-axis positive direction) of the cover plate 120 forms a terminal arrangement surface on which the terminals 130 are arranged. The cover plate 120 is provided with a gas exhaust valve 121 that exhausts gas from inside the container 100 when the internal pressure of the container 100 rises excessively. The gas exhaust valve 121 is a portion of the cover plate 120 that is thinner than other portions of the cover plate 120. The gas exhaust valve 121 and the configuration of its surroundings will be described later with reference to Figures 4 to 7. In this embodiment, the X-axis direction is an example of a first direction, the Y-axis direction is an example of a second direction, and the Z-axis direction is an example of a third direction.

The electrode body 400 is an electricity 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 includes a current collector foil (positive electrode metal foil) and an active material layer formed on the current collector foil. The negative electrode plate includes a current collector foil (negative electrode metal foil) and an active material layer formed on the current collector foil. Any known material can be used as the active material used in the active material layer, as long as it is capable of absorbing and releasing cations (lithium ions, sodium ions, magnesium ions, etc.). The separator can be a microporous sheet made of resin, a nonwoven fabric, or the like.

In this embodiment, the electrode body 400 is a wound type electrode body formed by winding a laminate in which a separator is disposed between a positive electrode plate and a negative electrode plate. Specifically, the electrode body 400 has a positive electrode plate and a negative electrode plate wound with a separator interposed therebetween, shifted from each other in the direction of the winding axis W (a virtual axis parallel to the X-axis direction in this embodiment). The positive electrode plate and the negative electrode plate have a portion (active material layer non-formed portion) at the end in the shifted direction where the active material layer is not formed and the current collector foil is exposed. In other words, the electrode body 400 includes an electrode body main body 410 and an electrode body end portion 420 that protrudes from the electrode body main body 410 in the positive direction of the X-axis and the negative direction of the X-axis, respectively. In this embodiment, the electrode body 400 is formed in a flat shape with a narrow width in the Y-axis direction, as shown in FIG. 3, and the main stacking direction of the electrode plates (positive electrode plate and negative electrode plate) is the Y-axis direction. In this embodiment, the electrode body 400 is illustrated as having an oval cross-sectional shape, but the cross-sectional shape of the electrode body 400 may be circular, elliptical, or the like.

The terminal 130 is made of aluminum, an aluminum alloy, copper, a copper alloy, or the like. In this embodiment, the terminal 130 has a flat portion to which a conductive member such as a bus bar is welded. The terminal 130 may have a shaft portion for fixing a conductive member such as a bus bar using a nut. As shown in FIG. 3, the terminal 130 has a terminal body portion 132 located outside the container 100, and a shaft portion 131 extending downward from the terminal body portion 132 and penetrating the wall portion of the container 100 (the cover plate 120 in this embodiment). The shaft portion 131 is inserted into the through hole 140a of the upper insulating member 140, the through hole 120a of the cover plate 120, the through hole 150a of the lower insulating member 150, and the through hole 510a of the current collector 500, and is crimped. As a result, the terminal 130 is fixed to the cover plate 120 together with the upper insulating member 140, the lower insulating member 150, and the current collector 500.

The current collector 500 has a terminal connection portion 510 and a pair of electrode body connection portions 520 extending from the terminal connection portion 510. The terminal connection portion 510 is connected to the shaft portion 131 of the terminal 130, and is fixed to the container 100 together with the lower insulating member 150. The pair of electrode body connection portions 520 are joined to the electrode body end portion 420. Ultrasonic joining, crimping joining, or the like is used as a method for joining the electrode body connection portions 520 to the electrode body end portion 420. The current collector 500 is formed of aluminum, an aluminum alloy, copper, a copper alloy, or the like.

The upper insulating member 140 is disposed between the cover plate 120 of the container 100 and the terminal body portion 132 of the terminal 130, and is a member that provides insulation between the cover plate 120 and the terminal 130. In this embodiment, the upper insulating member 140 also functions as a gasket that seals between the cover plate 120 and the shaft portion 131 of the terminal 130. The lower insulating member 150 is disposed between the cover plate 120 of the container 100 and the terminal connection portion 510 of the current collector 500, and is a member that provides insulation between the cover plate 120 and the current collector 500.

2. Configuration of the Gas Exhaust Valve 121 and Its Surroundings
FIG. 4 is a perspective view showing the gas exhaust valve 121 and its surrounding configuration according to the embodiment. In FIG. 4, a perspective view of the cover plate 120 viewed from diagonally below is shown. FIG. 5 is a plan view showing the gas exhaust valve 121 and its surrounding configuration according to the embodiment. In FIG. 5, a plan view of the cover plate 120 viewed from the protruding direction (Z-axis minus direction) of the first convex portion 123 and the second convex portion 124 provided thereon is shown. Hereinafter, the case where the object is viewed from the Z-axis minus direction is expressed as "in a plan view" or the like. FIG. 6 is a first cross-sectional view showing the gas exhaust valve 121 and its surrounding configuration according to the embodiment. In FIG. 6, a cross section taken along line VI-VI in FIG. 5 is shown. FIG. 7 is a second cross-sectional view showing the gas exhaust valve 121 and its surrounding configuration according to the embodiment. In FIG. 7, a cross section taken along line VII-VII in FIG. 5 is shown.

As shown in Figures 4 to 7, the cover plate 120 according to this embodiment includes a gas exhaust valve 121, a first convex portion 123, and a second convex portion 124. The gas exhaust valve 121 is a portion that is thinner than other portions of the cover plate 120. When the electrolyte inside the container 100 suddenly evaporates and the internal pressure increases, the gas exhaust valve 121 is deformed by expanding outward in response to the increase in internal pressure. As a result, the gas exhaust valve 121 breaks, etc., and an opening is formed in the cover plate 120 in the area where the gas exhaust valve 121 is located. Gas inside the container 100 is exhausted from this opening.

It is assumed that an external force acts on the cover plate 120, which is a wall portion having the gas exhaust valve 121 that performs such a valve opening operation, during use or manufacture of the energy storage device 10. In this case, the gas exhaust valve 121, which has a smaller thickness than other parts, may be deformed by the external force, and the strength of the gas exhaust valve may be reduced. In particular, the cover plate 120 according to this embodiment is elongated in the X-axis direction (see FIG. 3). Therefore, the cover plate 120 is likely to bend in the X-axis direction, which is the longitudinal direction. In other words, when viewed from the short side direction (Y-axis direction), the cover plate 120 is likely to be deformed so as to warp in the Z-axis direction. For example, when the shaft portion 131 arranged in the through hole 120a located in the X-axis direction of the gas exhaust valve 121 is crimped in the manufacturing process of the energy storage device 10, the force of the crimping may adversely affect the gas exhaust valve 121. In this embodiment, to address this issue, a convex portion is provided on each of the X-axis and Y-axis directions of the gas exhaust valve 121, and a structure is adopted that can effectively suppress bending of the portion of the cover plate 120 that includes the gas exhaust valve 121 in the X-axis direction.

Specifically, in the energy storage element 10 according to this embodiment, as shown in Figs. 4 to 7, the first convex portion 123 is disposed in the X-axis direction of the gas exhaust valve 121, and the second convex portion 124 is disposed in the Y-axis direction of the gas exhaust valve 121. As shown in Figs. 6 and 7, the width W2 of the second convex portion 124 in the Y-axis direction is greater than the width W1 of the first convex portion 123 in the X-axis direction.

According to this configuration, the portion of the cover plate 120 including the gas exhaust valve 121 includes a first convex portion 123 arranged in the X-axis direction of the gas exhaust valve 121 and a second convex portion 124 arranged in the Y-axis direction of the gas exhaust valve 121. Furthermore, the width W2 of the second convex portion 124 in the Y-axis direction is greater than the width W1 of the first convex portion 123 in the X-axis direction. Therefore, the second convex portion 124 improves the bending resistance in the X-axis direction of the portion of the cover plate 120 including the gas exhaust valve 121. In other words, bending of the portion in the X-axis direction such that a part of the portion is displaced in the thickness direction (Z-axis direction) of the wall portion is suppressed. As a result, when an external force acts on the cover plate 120 during the manufacture or use of the energy storage element 10, deformation of the gas exhaust valve 121 due to the external force is suppressed. In other words, the gas exhaust valve 121 is protected.

In this embodiment, the cover plate 120 is formed by pressing a metal plate, which is the base material of the cover plate 120, with the gas exhaust valve 121, the first convex portion 123, and the second convex portion 124 integrally therewith, using a mold. The first convex portion 123 and the second convex portion 124 are formed by metal that escapes outward from the position of the gas exhaust valve 121 when the gas exhaust valve 121, which is a thin-walled portion, is formed. In order to further improve the bending resistance of the cover plate 120 in the X-axis direction, it is possible to increase the widths of both the first convex portion 123 and the second convex portion 124 in a plan view. However, there are cases where it is difficult or practically impossible to increase the widths of both the first convex portion 123 and the second convex portion 124. In the energy storage element 10 according to this embodiment, the width W2 of the second convex portion 124 located in the Y-axis direction of the gas exhaust valve 121 is made larger than the width W1 of the first convex portion 123. This allows both the first convex portion 123 and the second convex portion 124 to be provided on the cover plate 120, and more effectively protects the gas exhaust valve 121 provided on the cover plate 120 that is elongated in the X-axis direction.

The gas exhaust valve 121 is located at the center of the cover plate 120 in the longitudinal direction (X-axis direction). The distance from the edge of the cover plate 120 to the gas exhaust valve 121 in the X-axis direction is longer than the distance from the edge of the cover plate 120 to the gas exhaust valve 121 in the Y-axis direction. As a result, when the gas exhaust valve 121 is molded, meat that attempts to escape to the outside from the position of the gas exhaust valve 121 is less likely to move in the longitudinal direction of the cover plate 120 (X-axis direction) and is more likely to move in the lateral direction of the cover plate 120 (Y-axis direction). In this embodiment, the first convex portion 123 and the second convex portion 124 are molded so that the width W2 of the second convex portion 124 is greater than the width W1 of the first convex portion 123. Therefore, when the width W2 of the second convex portion 124 and the width W1 of the first convex portion 123 are molded to be the same, defects such as poor molding of the first convex portion 123 (insufficient amount of metal) or poor shape of the cover plate 120 due to excessive metal escaping in the short direction of the cover plate 120 (Y-axis direction) are suppressed.

The manufacturing method of the energy storage element 10 configured as described above is described as follows. The energy storage element 10 comprises a container 100, which comprises a wall portion (cover plate 120) that is elongated in the X-axis direction. The manufacturing method of the energy storage element 10 includes forming the cover plate 120 by pressing a metal plate that is the base material of the cover plate 120. Forming the cover plate 120 includes forming the gas exhaust valve 121, which is a portion that is thinner than other portions of the cover plate 120, and forming a first convex portion 123 and a second convex portion 124 with metal that escapes to the outside from the position of the gas exhaust valve 121 when forming the gas exhaust valve 121. By forming the first convex portion 123 and the second convex portion 124, the first convex portion 123 is formed in the X-axis direction of the gas exhaust valve 121, and the second convex portion 124 is formed in the Y-axis direction of the gas exhaust valve 121, and the width W2 of the second convex portion 124 in the Y-axis direction is greater than the width W1 of the first convex portion 123 in the X-axis direction.

In this embodiment, as shown in FIG. 5, the first convex portion 123 extends along the entire area of the gas exhaust valve 121 in the Y-axis direction, and the second convex portion 124 extends along the entire area of the gas exhaust valve 121 in the X-axis direction. In this embodiment, the width W1 of the first convex portion 123 in the X-axis direction is the width of a position where a straight line L1 (see FIG. 5) passes through the first convex portion 123. The straight line L1 is an imaginary line that passes through the center of the gas exhaust valve 121 in the Y-axis direction and is parallel to the X-axis direction. The straight line L1 coincides with line VI-VI in FIG. 5. The width W2 of the second convex portion 124 in the Y-axis direction is the width of a position where a straight line L2 (see FIG. 5) passes through the second convex portion 124. The straight line L2 is an imaginary line that passes through the center of the gas exhaust valve 121 in the X-axis direction and is parallel to the Y-axis direction. L2 coincides with line VII-VII in FIG. 5. In other words, the first convex portion 123 can be described as facing the center of the gas exhaust valve 121 in the Y-axis direction in the X-axis direction in a plan view. The second convex portion 124 can be described as facing the center of the gas exhaust valve 121 in the X-axis direction in the Y-axis direction in a plan view.

In this embodiment, as shown in Figures 4 and 5, the first convex portion 123 is disposed in each of the positive and negative directions of the X-axis of the gas exhaust valve 121. The second convex portion 124 is disposed in each of the positive and negative directions of the Y-axis of the gas exhaust valve 121.

With this configuration, the gas exhaust valve 121 is disposed between the first convex portions 123 located on both sides in the X-axis direction, and between the second convex portions 124 located on both sides in the Y-axis direction. This ensures that the gas exhaust valve 121 is more reliably protected during assembly of the energy storage element 10, etc.

In this embodiment, in plan view, the cover plate 120 is formed with a series of protrusions 128 that include a first protrusion 123 and a second protrusion 124 and surround the gas exhaust valve 121.

In other words, the entire circumference of the gas exhaust valve 121 is surrounded by the protrusion 128 in a plan view. Therefore, the gas exhaust valve 121 is more reliably protected when assembling the energy storage element 10, etc.

In this embodiment, the protruding portion 128 is a portion that protrudes in the negative Z-axis direction of the cover plate 120, as shown in Figs. 4 to 7. The protruding portion 128 includes a pair of first protruding portions 123, a pair of second protruding portions 124, and a connecting portion 125 that connects adjacent first protruding portions 123 and second protruding portions 124. In this embodiment, the first protruding portion 123 has a substantially linear shape extending in the Y-axis direction, and the second protruding portion 124 has a substantially linear shape extending in the X-axis direction. The connecting portion 125 is provided on the protruding portion 128 as a portion that connects between the first protruding portion 123 and the second protruding portion 124 that extend in different directions. In other words, the connecting portion 125 is a portion that forms a corner of the protruding portion 128 that is provided in a rectangular shape as a whole in a plan view. Four connecting portions 125 are provided on the protruding portion 128.

In this embodiment, as shown in Figures 5 and 7, the second protrusion 124 and the gas exhaust valve 121 are arranged continuously in the Y-axis direction on the cover plate 120.

With this configuration, the second convex portion 124 and the gas exhaust valve 121 are arranged contiguously, simplifying the shape of the gas exhaust valve 121 and its surroundings on the cover plate 120. When forming the gas exhaust valve 121, which is a thin-walled portion, by press working, the metal that escapes in the Y-axis direction is used more efficiently to form the second convex portion 124. As a result, the second convex portion 124, which has a relatively large width in the Y-axis direction, can be formed with greater precision.

In this embodiment, the first convex portion 123 and the gas exhaust valve 121 are arranged continuously in the X-axis direction on the cover plate 120. This also contributes to simplifying the shape of the gas exhaust valve 121 and its surroundings on the cover plate 120. When forming the gas exhaust valve 121 by press working, the metal that escapes in the X-axis direction is used more efficiently to form the first convex portion 123. As a result, the first convex portion 123 can be formed with greater precision.

The above describes the energy storage element 10 according to the embodiment, focusing on the gas exhaust valve 121 and the configuration around it. The gas exhaust valve 121 and the configuration around it may be configured differently from the configuration shown in Figures 1 to 7. Below, modified examples of the gas exhaust valve 121 and the configuration around it will be described, focusing on the differences from the above embodiment.

[3-1. Modification 1]
Fig. 8 is a plan view showing the gas exhaust valve 221 and its surrounding configuration according to the first modified embodiment of the embodiment. Fig. 9 is a first cross-sectional view showing the gas exhaust valve 221 and its surrounding configuration according to the first modified embodiment of the embodiment. Fig. 9 shows a cross section taken along line IX-IX in Fig. 8. Fig. 10 is a second cross-sectional view showing the gas exhaust valve 221 and its surrounding configuration according to the first modified embodiment of the embodiment. Fig. 10 shows a cross section taken along line X-X in Fig. 8.

The energy storage element 10 according to this modified example includes a container 100, which includes a container body 110 (see FIG. 2) and a cover plate 220 shown in FIGS. 8 to 10. The overall shape of the cover plate 220 according to this modified example is the same as the cover plate 120 according to the embodiment, and is elongated in the X-axis direction. Components of the energy storage element 10, such as the terminals 130 not shown in FIGS. 8 to 10, are the same as those in the above embodiment, and therefore will not be described here. The same applies to modified example 2, which will be described later.

The cover plate 220 according to this modified example is a wall portion of the container 100, and is a plate-like member that forms the outer surface 220b and the inner surface 220c. As shown in FIGS. 8 to 10, the cover plate 220 includes a gas exhaust valve 221, a first convex portion 223, and a second convex portion 224. The gas exhaust valve 221 is a portion having a smaller thickness than other portions of the cover plate 220. The first convex portion 223 is disposed in the X-axis direction of the gas exhaust valve 221, and the second convex portion 224 is disposed in the Y-axis direction of the gas exhaust valve 221. As shown in FIGS. 9 and 10, the width W2a of the second convex portion 224 in the Y-axis direction is larger than the width W1a of the first convex portion 223 in the X-axis direction. More specifically, the cover plate 220 includes a protrusion 228 that includes the first convex portion 223 and the second convex portion 224, and is a series of protrusions 228 that surround the gas exhaust valve 221. The protrusion 228 further includes a connection portion 225 that connects the adjacent first protrusion 223 and second protrusion 224. These configurations are common to the cover plate 120 included in the energy storage device 10 according to the embodiment. Therefore, according to the energy storage device 10 according to this modified example, the bending resistance in the X-axis direction of the portion of the cover plate 220 including the gas exhaust valve 221 is improved.

In the cover plate 220 according to this modification, the second convex portion 224 and the gas exhaust valve 221 are not arranged continuously in the Y-axis direction, and in this respect it differs from the cover plate 120 according to the embodiment. In this modification, an intermediate portion 227 having a thickness greater than that of the gas exhaust valve 221 is arranged between the second convex portion 224 and the gas exhaust valve 221 in the cover plate 220. More specifically, the intermediate portion 227 is a portion having a thickness greater than that of the gas exhaust valve 221 and less than that of the portion of the cover plate 220 where the protrusion 228 is arranged.

With this configuration, the shape of the second convex portion 224 and the shape of the gas exhaust valve 221 are independent of each other in a plan view. Therefore, the shape of the second convex portion 224 can be determined without depending on the shape of the gas exhaust valve 221. Alternatively, the shape of the gas exhaust valve 221 can be determined without depending on the shape of the second convex portion 224.

In this modified example, in plan view, the entire circumference of the gas exhaust valve 221 is surrounded by the intermediate portion 227, and the entire circumference of the intermediate portion 227 is surrounded by the protruding portion 228. In other words, the intermediate portion 227 is also disposed between the first convex portion 223 and the gas exhaust valve 221. Therefore, as shown in FIG. 8, a protruding portion 228 having a substantially rectangular shape and elongated in the X-axis direction in plan view can be disposed on the gas exhaust valve 221 having a substantially square shape in plan view. The shape of the gas exhaust valve 221 in plan view is not limited to a substantially square shape, and may be an elliptical shape, an oval shape, or a polygonal shape other than a rectangle.

The intermediate portion 227 does not have to surround the entire circumference of the gas exhaust valve 221 in a plan view. The intermediate portion 227 may be disposed on at least one of the sides in the X-axis direction of the gas exhaust valve 221. In other words, the intermediate portion 227 may be disposed only in the X-axis direction of the gas exhaust valve 221, and the intermediate portion 227 may not be disposed in the Y-axis direction of the gas exhaust valve 221. Similarly, the intermediate portion 227 may be disposed on at least one of the sides in the Y-axis direction of the gas exhaust valve 221. In other words, the intermediate portion 227 may be disposed only in the Y-axis direction of the gas exhaust valve 221, and the intermediate portion 227 may not be disposed in the X-axis direction of the gas exhaust valve 221.

[3-2. Modification 2]
Fig. 11 is a plan view showing the gas exhaust valve 321 and its surrounding configuration according to the second modification of the embodiment. Fig. 12 is a first cross-sectional view showing the gas exhaust valve 321 and its surrounding configuration according to the second modification of the embodiment. Fig. 12 shows a cross-section taken along line XII-XII in Fig. 11. Fig. 13 is a second cross-sectional view showing the gas exhaust valve 321 and its surrounding configuration according to the second modification of the embodiment. Fig. 13 shows a cross-section taken along line XIII-XIII in Fig. 11.

The energy storage element 10 according to this modification includes a container 100, which includes a container body 110 (see FIG. 2) and a cover plate 320. The cover plate 320 according to this modification is a wall portion of the container 100, and is a plate-like member that forms an outer surface 320b and an inner surface 320c. As shown in FIGS. 11 to 13, the cover plate 320 includes a gas exhaust valve 321, a first convex portion 323, and a second convex portion 324. The gas exhaust valve 321 is a portion having a smaller thickness than other portions of the cover plate 320. The first convex portion 323 is disposed in the X-axis direction of the gas exhaust valve 321, and the second convex portion 324 is disposed in the Y-axis direction of the gas exhaust valve 321. As shown in FIGS. 12 and 13, the width W2b of the second convex portion 324 in the Y-axis direction is greater than the width W1b of the first convex portion 323 in the X-axis direction. More specifically, the cover plate 320 is formed with a series of protrusions 328 including a first protrusion 323 and a second protrusion 324, which surround the gas exhaust valve 321. These configurations are common to the cover plate 120 of the energy storage device 10 according to the embodiment. According to the energy storage device 10 according to this modified example, the bending resistance in the X-axis direction of the portion of the cover plate 320 including the gas exhaust valve 321 is improved.

In the cover plate 320 of this modified example, the second protrusion 324 and the gas exhaust valve 321 are arranged continuously in the Y-axis direction. This point is also the same as the cover plate 120 of the embodiment. Therefore, the shape of the gas exhaust valve 321 and its surroundings in the cover plate 320 is simplified.

In this modified example, as shown in FIG. 11, the first convex portion 323 and the second convex portion 324 are formed in a curved shape in which the first convex portion 323 and the second convex portion 324 are continuous in a plan view. As a result, the shape of the protrusion 328 is approximately elliptical in a plan view. In the protrusion 328 having such a first convex portion 323 and second convex portion 324, the first convex portion 323 includes at least a portion through which the straight line L1 passes, and the second convex portion 324 includes at least a portion through which the straight line L2 passes. The straight line L1 is an imaginary line that passes through the center of the gas exhaust valve 321 in the Y-axis direction and is parallel to the X-axis direction. The straight line L1 coincides with the line XII-XII in FIG. 11. The straight line L2 is an imaginary line that passes through the center of the gas exhaust valve 321 in the X-axis direction and is parallel to the Y-axis direction. L2 coincides with the line XIII-XIII in FIG. 11. That is, the first convex portion 323 faces the center of the gas exhaust valve 321 in the Y axis direction in the X axis direction in a plan view. The second convex portion 324 faces the center of the gas exhaust valve 321 in the X axis direction in the Y axis direction in a plan view.

In the cover plate 320 according to this modified example, the second convex portion 324 and the gas exhaust valve 321 do not have to be continuous in the Y-axis direction. An intermediate portion having a thickness greater than that of the gas exhaust valve 321 may be disposed between the second convex portion 324 and the gas exhaust valve 321. In this case, the shape of the second convex portion 324 can be determined independently of the shape of the gas exhaust valve 321. Alternatively, the shape of the gas exhaust valve 321 can be determined independently of the shape of the second convex portion 324.

[3-3. Energy storage device 700 including energy storage element 10]
Fig. 14 is a plan view showing a schematic configuration of an energy storage device 700 including an energy storage element 10 according to an embodiment. As shown in Fig. 14, the energy storage element 10 may be used in the energy storage device 700. In this case, the technology of the present invention may be applied to at least one energy storage element 10 included in the energy storage device 700.

The energy storage device 700 shown in FIG. 10 includes a plurality of energy storage units 600 arranged therein. The energy storage unit 600 is composed of a plurality of energy storage elements 10 that are electrically connected. The energy storage device 700 may include a bus bar (not shown) that electrically connects the plurality of energy storage elements 10, and a bus bar (not shown) that electrically connects the plurality of energy storage units 600. The energy storage unit 600 or the energy storage device 700 may include a status monitoring device (not shown) that monitors the status of one or more energy storage elements 10. The energy storage device 700 may include only one energy storage unit 600. In this case, the energy storage unit 600 may be referred to as an "energy storage device".

In this modification, the energy storage device 700 includes one or more energy storage elements 10 according to the above embodiment, but the energy storage device 700 may include an energy storage element 10 according to modification 1 or 2 instead of or in addition to the one or more energy storage elements 10.

[4. Description of other modified examples]
Although the energy storage element 10 according to the embodiment and the modified example thereof of the present invention has been described above, the present invention is not limited to the above-mentioned embodiment and the modified example. The embodiment and the modified example disclosed herein are illustrative in all respects, and the scope of the present invention includes all modifications within the meaning and scope equivalent to the claims.

6 and 7, in the energy storage device 10 according to the embodiment, the position of the gas exhaust valve 121 in the Z-axis direction is in the negative Z-axis direction from the inner surface 120c of the cover plate 120, but this is not essential. The position of the gas exhaust valve 121 in the Z-axis direction may be substantially the same as the outer surface 120b of the cover plate 120, or may be between the outer surface 120b and the inner surface 120c of the cover plate 120. In other words, it is not essential that a recess with the gas exhaust valve 121 as its inner bottom surface is formed in the cover plate 120. However, from the viewpoint of avoiding contact between the gas exhaust valve 121 and an object disposed outside the energy storage device 10, it is preferable that the position of the gas exhaust valve 121 in the Z-axis direction is in the negative Z-axis direction from the outer surface 120b of the cover plate 120.

As shown in Figures 4 to 7, the first convex portion 123 and the second convex portion 124 protrude in the negative Z-axis direction from the inner surface 120c of the cover plate 120, but this is not essential. The first convex portion 123 and the second convex portion 124 may protrude in the positive Z-axis direction from the outer surface 120b of the cover plate 120. However, if there is a possibility that some member is arranged at a position opposite the outer surface 120b of the cover plate 120 in the Z-axis direction, it is preferable that the first convex portion 123 and the second convex portion 124 protrude in the negative Z-axis direction from the inner surface 120c of the cover plate 120. In this case, the first convex portion 123 and the second convex portion 124 are arranged in the space between the inner surface 120c of the cover plate 120 and the electrode body 400. More specifically, as shown in Figure 3, the terminal connection portion 510 of the collector 500 and the lower insulating member 150 are arranged in the negative Z-axis direction of the inner surface 120c of the cover plate 120. Therefore, a space (gap) is formed between the inner surface 120c of the cover plate 120 and the electrode body 400, the distance of which is longer than the total thickness of the terminal connection portion 510 and the lower insulating member 150. When the first convex portion 123 and the second convex portion 124 protrude from the inner surface 120c of the cover plate 120 toward the inside of the container body 110 (see FIG. 2), the first convex portion 123 and the second convex portion 124 are accommodated in the gap. This prevents the first convex portion 123 and the second convex portion 124 from wasting the internal volume of the container 100.

The protruding portion 128 (see Figs. 4 and 5) may not have the connecting portion 125. In other words, the protruding portion 128 may be composed of only a pair of first protruding portions 123 extending in the Y-axis direction in a plan view and a pair of second protruding portions 124 extending in the X-axis direction in a plan view. In the cover plate 120 according to the embodiment, the first protruding portion 123 may be arranged in at least one of the positive direction and the negative direction of the X-axis of the gas exhaust valve 121, and the second protruding portion 124 may be arranged in at least one of the positive direction and the negative direction of the Y-axis of the gas exhaust valve 121. In either case, the gas exhaust valve 121 is protected by the first protruding portion 123 and the second protruding portion 124. In particular, the second protruding portion 124 is effective in protecting the gas exhaust valve 121 provided on the cover plate 120, which is easily bent in the X-axis direction when subjected to an external force.

The second convex portion 124 does not need to extend along the entire area of the gas exhaust valve 121 in the X-axis direction. In a plan view, the second convex portion 124 only needs to face in the Y-axis direction the center of the gas exhaust valve 121 in the X-axis direction. The first convex portion 123 does not need to extend along the entire area of the gas exhaust valve 121 in the Y-axis direction. In a plan view, the first convex portion 123 only needs to face in the X-axis direction the center of the gas exhaust valve 121 in the Y-axis direction.

In the container 100, the wall portion on which the gas exhaust valve 121 is provided does not have to be the cover plate 120. In other words, any one of the first side wall portion 111, the second side wall portion 112, and the bottom wall portion 113 (see FIG. 2) of the container body 110 may be the wall portion on which the gas exhaust valve 121 is provided. When a wall portion integrally including the gas exhaust valve 121, the first convex portion 123, and the second convex portion 124 is formed by press processing, from the viewpoint of ease of forming the wall portion, it is preferable that the wall portion on which the gas exhaust valve 121 is provided is the cover plate 120.

Although the terminal 130 and the current collector 500 are joined by crimping the shaft portion 131 of the terminal 130, the terminal 130 and the current collector 500 may be joined by a method other than crimping. The terminal 130 and the current collector 500 may be joined by welding the shaft portion 131 to the current collector 500. The terminal 130 and the current collector 500 may be joined by inserting the shaft portion 131 into the through hole 510a (see FIG. 3) of the current collector 500 and connecting a nut to the portion of the shaft portion 131 protruding from the through hole 510a. In either case, some external force may act on the cover plate 120 during assembly or transportation of the energy storage element 10, and this external force may adversely affect the gas exhaust valve 121. However, by providing the cover plate 120 with the first convex portion 123 and the second convex portion 124, deformation of the gas exhaust valve 121 caused by the external force is suppressed. In other words, the gas exhaust valve 121 is protected.

The gas exhaust valve 121 does not need to have a uniform thickness. The gas exhaust valve 121 may have a groove that forms a thinner portion. The groove may function as a groove (fracture groove) that makes the gas exhaust valve 121 easier to break. From the viewpoint of making the gas exhaust valve 121 easier to break when the internal pressure of the container 100 rises excessively, the fracture groove is preferably a groove that (i) extends in a direction that is not parallel to the second direction (the Y-axis direction in the embodiment). From this viewpoint, the fracture groove is preferably (ii) formed of two or more grooves that intersect in a planar view. From this viewpoint, the fracture groove is preferably (iii) formed of a bent or curved portion in a planar view. The fracture groove may be a groove that has two or more of the three characteristics shown in (i), (ii), and (iii) above.

If the gas release valve 121 has a fracture groove, it is considered that an external force (external force not caused by an increase in the internal pressure of the container 100) acting on the wall of the container 100 (the cover plate 120 in the embodiment) during assembly or transportation of the energy storage element 10 is likely to adversely affect the fracture groove. However, by providing the cover plate 120 with the first convex portion 123 and the second convex portion 124, deformation of the gas release valve 121 due to the external force is suppressed. This protects the fracture groove having at least one of the above characteristics (i) to (iii). In other words, the occurrence of defects such as deformation or breakage of the fracture groove caused by the external force is suppressed. Among the above (i), it is considered that the groove extending in a direction parallel to the first direction is more likely to be adversely affected by the external force. Therefore, it is more beneficial for the cover plate 120 to have the first convex portion 123 and the second convex portion 124 in terms of suppressing the occurrence of defects in the fracture groove including the groove.

The wound electrode body 400 (see FIG. 3) provided in the energy storage element 10 is housed in the container 100 with the winding axis W parallel to the X-axis direction. The orientation of the electrode body 400 is not limited to this. The electrode body 400 may be housed in the container 100 with the winding axis W parallel to the Z-axis direction. In this case, the electrode body 400 may have a pair of tab portions protruding from the electrode body main body 410 in the positive direction of the Z-axis, instead of the pair of electrode body ends 420. The current collector 500 may have a connection portion of a size and shape that can be connected to the tab portions of the electrode body 400, instead of the pair of electrode body connection portions 520.

The type of electrode body provided in the energy storage element 10 is not limited to the wound type. The energy storage element 10 may be provided with a laminated electrode body in which flat electrode plates are stacked, or an electrode body having a structure in which long strip-shaped electrode plates are stacked in a bellows shape by repeatedly folding in peaks and valleys. The number of electrode bodies provided in the energy storage element 10 is also not limited to one. The energy storage element 10 may be provided with two or more electrode bodies.

The supplementary information regarding the energy storage element 10 according to the embodiment described above may be applied to the energy storage element 10 according to each of the first and second variations of the embodiment. Configurations constructed by arbitrarily combining the components included in the above embodiment and its variations are also included within the scope of the present invention.

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 120, 220, 320 Cover plate 121, 221, 321 Gas exhaust valve 123, 223, 323 First convex portion 124, 224, 324 Second convex portion 125, 225 Connection portion 128, 228, 328 Protruding portion 227 Middle portion

Claims (6)

An energy storage element including a container,
The container has a wall that is elongated in a first direction;
the wall portion includes a gas exhaust valve, a first convex portion, and a second convex portion,
the gas exhaust valve is a portion of the wall portion having a smaller thickness than other portions of the wall portion,
the first protrusion is disposed in the first direction of the gas exhaust valve,
The second protrusion is disposed in a second direction of the gas release valve that is perpendicular to the first direction,
A width of the second convex portion in the second direction is larger than a width of the first convex portion in the first direction.
Energy storage element. the first convex portions are disposed on one side and the other side of the gas exhaust valve in the first direction,
The second convex portions are arranged on one side and the other side of the gas exhaust valve in the second direction,
The energy storage element according to claim 1. When viewed from a third direction perpendicular to the first direction and the second direction, the wall portion has a series of protruding portions including the first convex portion and the second convex portion, the series of protruding portions surrounding the gas exhaust valve.
The energy storage element according to claim 2. In the wall portion, the second convex portion and the gas exhaust valve are arranged continuously in the second direction.
The energy storage element according to any one of claims 1 to 3. In the wall portion, an intermediate portion having a thickness larger than that of the gas exhaust valve is disposed between the second convex portion and the gas exhaust valve.
The energy storage element according to any one of claims 1 to 3. A method for manufacturing an energy storage element including a container, comprising:
The container has a wall that is elongated in a first direction;
The manufacturing method includes:
forming the wall portion by pressing a metal plate that is a base material of the wall portion;
Shaping the wall portion comprises:
Molding a gas exhaust valve, which is a portion of the wall portion having a thickness smaller than that of other portions of the wall portion; and
forming a first protrusion and a second protrusion by metal escaping outward from a position of the gas exhaust valve when forming the gas exhaust valve;
By molding the first convex portion and the second convex portion,
The first protrusion is formed in the first direction of the gas exhaust valve,
The second protrusion is formed in the gas exhaust valve in a second direction perpendicular to the first direction, and
A width of the second convex portion in the second direction is larger than a width of the first convex portion in the first direction.
A method for manufacturing an energy storage element.

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