JP2022055793A - Power storage element - Google Patents

Abstract

To provide a power storage element, equipped with a collector for electrically connecting an electrode body to an electrode terminal, which has improved safety.SOLUTION: A power storage element 10 comprises: an electrode body 200; an electrode terminal 130; and a collector 300 for electrically connecting the electrode body 200 to the electrode terminal 130. The collector 300 has: a terminal connection part 310 which is connected to the electrode terminal 130 and is disposed at a position side by side in a Z-axis direction with the electrode body 200; and a leg part 320 which is erected from the terminal connection part 310 in the Z-axis direction and is bonded to the electrode body 200. A high-rigidity part 325 having rigidity higher than that of the terminal connection part 310 is formed between the terminal connection part 310 and a bonding part 330 which is a portion, of the leg part 320, bonded to the electrode body 200.SELECTED DRAWING: Figure 4

Description

The present invention relates to a power storage element including a current collector that electrically connects an electrode body and an electrode terminal.

Patent Document 1 discloses a current collecting terminal provided in a battery and bonded to a current collecting foil of an electrode body. In this current collector terminal, a reinforcing member is arranged on the opposite side of the joint surface with the current collector foil.

JP-A-2019-125486

In the current collector terminal (current collector) in the above-mentioned conventional technique, by arranging a reinforcing member on the opposite side of the surface to be joined to the electrode body, plastic deformation of the current collector during pressure contact with the electrode body can be suppressed. I'm trying. However, the current collector provided in the power storage element is arranged in a state of being connected to, for example, an electrode terminal fixed to a container. That is, the current collector is arranged in the container so that one end in the longitudinal direction is a fixed end and the other end is a free end, and supports the electrode body. Therefore, for example, when an impact is applied to the power storage element, stress concentration tends to occur in a portion of the current collector near the root (fixed end) on the container side due to the inertial force of the electrode body. As a result, the current collector is plastically deformed, which causes a problem that causes an unsafe event such as damage to the electrode body due to the current collector. Regarding such a problem, since the reinforcing member in the above-mentioned conventional technique is arranged at the joint portion with the electrode body in the current collector, the effect of suppressing the plastic deformation of the current collector due to the above-mentioned stress concentration is expected. Can not.

The present invention has been made by the inventor of the present application paying new attention to the above-mentioned problems, and is a power storage element provided with a current collector that electrically connects an electrode body and an electrode terminal, and has improved safety. It is an object of the present invention to provide a power storage element.

The power storage element according to one aspect of the present invention is a power storage element including an electrode body, an electrode terminal, and a current collector for electrically connecting the electrode body and the electrode terminal. A terminal connection portion connected to the electrode terminal and arranged at a position aligned with the electrode body in the first direction, and a leg erected from the terminal connection portion along the first direction and joined to the electrode body. A high-hardness portion having a portion higher than that of the terminal connection portion is formed between the joint portion, which is a portion of the leg portion that is joined to the electrode body, and the terminal connection portion. ..

According to this configuration, for example, when an impact is applied to the power storage element, an inertial force generated on the electrode body acts directly between the joint portion and the terminal connection portion forming the fixed end of the current collector. A high hardness portion having a hardness higher than that of the terminal connection portion is provided. Therefore, for example, it is possible to effectively suppress the deformation of the leg portion joined to the electrode body without adding a shape modification to the leg portion, and as a result, the possibility of the leg portion being plastically deformed is reduced. To. As a result, for example, the occurrence of defects such as the deformed leg portion damaging the electrode body is reduced. As described above, the power storage element according to this aspect is a power storage element including a current collector that electrically connects the electrode body and the electrode terminal, and is a power storage element with improved safety.

The high hardness portion may be formed in a range including the end portion of the leg portion on the terminal connection portion side.

According to this configuration, when the joint portion receives an external force, a high hardness portion is formed in a range including the end portion on the terminal connection portion side where stress is most likely to be concentrated in the leg portion. Therefore, the deformation of the leg can be suppressed more effectively, which further reduces the possibility of the leg being plastically deformed.

The leg portion is a wide portion provided at the end portion of the leg portion main body having the joint portion, and the width in the thickness direction of the leg portion main body and the width in the second direction intersecting the first direction are as follows. It may have a wide portion that becomes wider as it approaches the terminal connection portion, and the high hardness portion may be formed in a region continuous with the leg portion main body and the wide portion.

According to this configuration, since the wide portion is provided at the base portion of the leg portion, the deformation of the leg portion when the leg portion main body receives an external force is suppressed. Further, a high hardness portion is provided so as to straddle the boundary between the leg portion main body and the wide portion, which is a portion where stress is easily concentrated in this structure. Therefore, the effect of suppressing the deformation of the leg portion by the high hardness portion is further improved, and as a result, the possibility of the leg portion being plastically deformed is further reduced.

In the current collector, the connecting portion between the leg portion and the terminal connecting portion is provided with a bent portion formed in a curved or bent shape, and the high hardness portion is provided in the first direction. It may be formed on the side of the electrode body with respect to the bent portion.

According to this configuration, for example, by bending a plate-shaped member, a bent portion which is a connection portion between the terminal connection portion and the leg portion is formed, so that the bent portion is avoided and the high hardness portion is formed. Therefore, the bending process for forming the bent portion is not hindered by the high hardness portion. That is, it has a structure that suppresses the plastic deformation of the leg portion, and the manufacturing process that involves bending can be efficiently performed. That is, it is possible to efficiently manufacture a power storage element with improved safety.

The high-hardness portion may be formed thinner than the portion other than the high-hardness portion in the current collector.

According to this configuration, for example, high hardness in a high hardness portion can be realized by work hardening by thinning a part of a metal plate by press working. Therefore, for example, a current collector having a high hardness portion can be easily produced by using a metal plate such as an aluminum alloy that is generally distributed. That is, it is possible to efficiently manufacture a power storage element with improved safety.

It should be noted that the present invention can be realized not only as such a power storage element but also as a current collector included in the power storage element.

According to the present invention, it is possible to provide a power storage element provided with a current collector that electrically connects an electrode body and an electrode terminal, and has improved safety.

It is a perspective view which shows the appearance of the power storage element which concerns on embodiment. It is a 1st exploded perspective view of the power storage element which concerns on embodiment. It is a second exploded perspective view of the power storage element which concerns on embodiment. It is a perspective view which shows the structure of the current collector which concerns on embodiment. It is a side view of the current collector which concerns on embodiment. It is a rear view of the current collector which concerns on embodiment. It is an enlarged perspective view which shows the end part on the terminal connection part side of the current collector which concerns on embodiment. It is a perspective view which shows the structure of the current collector which concerns on the modification of embodiment.

Hereinafter, the power storage element according to the embodiment of the present invention (including a modification thereof) will be described with reference to the drawings. It should be noted that all of the embodiments described below show comprehensive or specific examples. The numerical values, shapes, materials, components, arrangement positions and connection forms of the components, manufacturing processes, order of manufacturing processes, etc. shown in the following embodiments are examples, and are not intended to limit the present invention. Further, in each figure, the dimensions and the like are not exactly shown. Further, in each figure, the same or similar components are designated by the same reference numerals.

In the following description and drawings, the arrangement direction of the pair of electrode terminals (positive electrode and negative electrode, the same applies hereinafter) of the power storage element, the arrangement direction of the pair of current collectors, the winding axis direction of the electrode body, or the short of the container. The facing direction of the side surfaces is defined as the X-axis direction. The direction opposite to the long side surface of the container, the short side direction of the short side surface of the container, or the thickness direction of the container is defined as the Y-axis direction. The alignment direction between the container body and the lid of the current collector element, the longitudinal direction of the short side surface of the container, or the extension direction of the legs of the current collector is defined as the Z-axis direction. These X-axis directions, Y-axis directions, and Z-axis directions intersect each other (orthogonally in the present embodiment).

Further, in the following description, for example, the X-axis plus direction indicates the arrow direction of the X-axis, and the X-axis minus direction indicates the direction opposite to the X-axis plus direction. The same applies to the Y-axis direction and the Z-axis direction. Further, in the following, the Z-axis direction may be referred to as a first direction, and the X-axis direction may be referred to as a second direction. Further, expressions indicating relative directions or postures such as parallel and orthogonal include cases where they are not strictly the directions or postures. For example, the fact that two directions are parallel not only means that the two directions are completely parallel, but also that they are substantially parallel, that is, that they include a difference of, for example, about several percent. Also means.

(Embodiment)
[1. General explanation of power storage element]
First, with reference to FIGS. 1 to 3, a general description of the power storage element 10 according to the present embodiment will be given. FIG. 1 is a perspective view showing the appearance of the power storage element 10 according to the embodiment. Further, FIG. 2 is a first exploded perspective view of the power storage element 10 according to the embodiment, and FIG. 3 is a second exploded perspective view of the power storage element 10 according to the embodiment. Specifically, FIG. 2 is a perspective view showing a state in which the container body 110 is separated from the power storage element 10. FIG. 3 is a perspective view showing a state in which components other than the container body 110 shown in FIG. 2 are disassembled.

The power storage element 10 is a secondary battery (single battery) capable of charging electricity and discharging electricity, and more specifically, a non-aqueous electrolyte secondary battery such as a lithium ion secondary battery. .. The power storage element 10 is, for example, a battery for driving a moving body such as an automobile, a motorcycle, a watercraft, a ship, a snowmobile, an agricultural machine, a construction machine, or a railroad vehicle for an electric railway, or for starting an engine. Used. Examples of the above-mentioned vehicle include an electric vehicle (EV), a hybrid electric vehicle (HEV), a plug-in hybrid electric vehicle (PHEV), and a gasoline vehicle. Examples of the railcars for electric railways include trains, monorails, maglev trains, and hybrid trains equipped with both diesel engines and electric motors. Further, the power storage element 10 can also be used as a stationary battery or the like used for home use, a generator, or the like.

The power storage element 10 is not limited to the non-aqueous electrolyte secondary battery, and may be a secondary battery other than the non-aqueous electrolyte secondary battery, or may be a capacitor. Further, the power storage element 10 may be a primary battery that can use the stored electricity without being charged by the user, instead of the secondary battery. Further, the power storage element 10 may be a battery using a solid electrolyte. Further, in the present embodiment, the rectangular parallelepiped (square) power storage element 10 is shown, but the shape of the power storage element 10 is not limited to the rectangular parallelepiped shape, and is not limited to the rectangular parallelepiped shape, the oblong columnar shape, or many other than the rectangular parallelepiped shape. It may have a rectangular parallelepiped shape or the like.

As shown in FIG. 1, the power storage element 10 includes a container 100, electrode terminals 130 for positive and negative electrodes, and an upper gasket 140 for positive and negative electrodes. Further, as shown in FIGS. 2 and 3, the inner side of the container 100 houses the lower gasket 150 of the positive electrode and the negative electrode, the electrode body 200, and the current collector 300 of the positive electrode and the negative electrode. An electrolytic solution (non-aqueous electrolyte) is sealed inside the container 100, but the illustration is omitted. The type of the electrolytic solution is not particularly limited as long as it does not impair the performance of the power storage element 10, and various types can be selected. Further, a spacer (not shown), an insulating film, or the like may be arranged inside the container 100.

The container 100 is a rectangular parallelepiped (square) container having a container body 110 in which an opening is formed and a lid body 120 that closes the opening of the container body 110. The container main body 110 is a rectangular cylindrical member having a bottom constituting the main body portion of the container 100, has short side surface portions 111 on both sides in the X-axis direction, and has long side surface portions 112 on both sides in the Y-axis direction. However, the bottom wall portion 113 is provided on the negative direction side of the Z axis. The short side surface portion 111 is a rectangular and plate-shaped wall portion forming the short side surface of the container 100, and the long side surface portion 112 is a wall portion forming the long side surface of the container 100.

The lid body 120 is a rectangular plate-shaped member constituting the lid portion of the container 100, and is arranged on the Z-axis plus direction side of the container body 110. That is, the lid 120 is a wall portion facing the bottom wall portion 113 and adjacent to the short side surface portion 111 and the long side surface portion 112. In the present embodiment, the electrode terminals 130 on the positive electrode side and the negative electrode side are fixed to the lid 120, and further, a gas discharge valve 121 that releases the pressure when the pressure inside the container 100 rises is also provided. It is provided.

With such a configuration, in the container 100, the electrode body 200 in a state where the pair of current collectors 300 are connected is housed inside the container body 110, and then the container body 110 and the lid body 120 are joined by welding or the like. As a result, the inside is sealed. The material of the container body 110 and the lid 120 is not particularly limited, and can be a weldable metal such as stainless steel, aluminum, or an aluminum alloy, but a resin can also be used.

The electrode body 200 includes a positive electrode plate, a negative electrode plate, and a separator, and is a power storage element (power generation element) capable of storing electricity. The positive electrode plate is an electrode plate in which a mixture layer containing a positive electrode active material is formed on a positive electrode base material layer which is a long strip-shaped current collecting foil made of aluminum, an aluminum alloy, or the like. The negative electrode plate is an electrode plate in which a mixture layer containing a negative electrode active material is formed on a negative electrode base material layer which is a long strip-shaped current collecting foil made of copper, a copper alloy, or the like. As the current collector foil, known materials such as nickel, iron, stainless steel, titanium, calcined carbon, conductive polymer, conductive glass, and Al—Cd alloy can be used as appropriate. Further, as the positive electrode active material and the negative electrode active material used for the mixture layer, known materials can be appropriately used as long as they are active materials that can occlude and release lithium ions. Further, as the separator, for example, a microporous sheet made of resin or a non-woven fabric can be used.

In the present embodiment, the electrode body 200 is a winding type electrode body 200 formed by arranging and winding a separator between a positive electrode plate and a negative electrode plate. Specifically, in the electrode body 200, the positive electrode plate and the negative electrode plate are wound by shifting each other in the direction of the winding axis W (virtual axis parallel to the X-axis direction in the present embodiment) via the separator. Has been done. Then, in the positive electrode plate and the negative electrode plate, a portion (mixture material) in which the base material layer is exposed without coating the mixture material containing the active material (the mixture material layer is not formed) at the end portions in the shifted directions. It has a layer non-forming portion).

That is, the electrode body 200 includes an electrode body main body 210, which is a main body on which a composite material layer is formed, and an electrode body end 220 projecting from the electrode body main body 210 in the X-axis positive direction or the X-axis negative direction. Have. The electrode body end 220 of one of these two electrode body end portions 220 is provided with a positive electrode focusing portion in which a mixture layer non-forming portion of the positive electrode plate is laminated and bundled. Further, the other electrode body end portion 220 is provided with a negative electrode focusing portion in which a mixture layer non-forming portion of the negative electrode plate is laminated and bundled. In the present embodiment, the electrode body 200 having an oval cross-sectional shape is shown, but the cross-sectional shape of the electrode body 200 may be a circular shape, an elliptical shape, or the like.

The electrode terminal 130 is a terminal (positive electrode terminal and negative electrode terminal) electrically connected to the positive electrode plate and the negative electrode plate of the electrode body 200 via the current collector 300. That is, the electrode terminal 130 leads the electricity stored in the electrode body 200 to the external space of the power storage element 10, and also introduces electricity into the internal space of the power storage element 10 in order to store electricity in the electrode body 200. It is a metal member of. Further, the electrode terminal 130 is fixed to the lid 120 arranged above the electrode body 200. Specifically, in the electrode terminal 130, the shaft portion 131 has a through hole 140a of the upper gasket 140, a through hole 120a of the lid body 120, a through hole 150a of the lower gasket 150, and a through hole 311 of the current collector 300. By being inserted into and crimped, it is fixed to the lid 120 together with the current collector 300. The electrode terminal 130 on the positive electrode side is made of aluminum or an aluminum alloy, and the electrode terminal 130 on the negative electrode side is made of copper or a copper alloy.

The current collector 300 is a member (positive electrode current collector and negative electrode current collector) arranged on both sides of the electrode body 200 in the X-axis direction and connected to the electrode body end portion 220. Specifically, the current collector 300 is an end portion fixed to the container 100 together with a lower gasket 150 which is an example of an insulating member, and is a terminal connection portion 310 which is an end portion connected to the electrode terminal 130 and a terminal. It has a pair of legs 320 extending from the connecting portion 310. The pair of leg portions 320 of the current collector 300 on the positive electrode side are joined to the electrode body end portion 220 on the positive electrode side, and the pair of leg portions 320 of the current collector 300 on the negative electrode side are the electrode body end portions 220 on the negative electrode side. Is joined to. That is, a joint portion 330, which is a portion joined to the electrode body end portion 220, is formed on each of the pair of leg portions 320. In the drawings after FIG. 2, the approximate arrangement range of the joint portion 330 in the current collector 300 is represented by the area with dots. It is not necessary that all of the regions with the dots are joined to the electrode body end 220, and the portions where the legs 320 and the electrode body end 220 are joined are dispersedly arranged in the region. May be. Further, the position, shape, and size of the joint portion 330 shown in FIG. 2 and the like are examples, and the position and the like of these joint portions 330 may be appropriately determined according to the size or shape of the leg portion 320 and the like.

As a method of joining the current collector 300 and the electrode body end 220, ultrasonic welding, caulking or the like is adopted. With this configuration, the electrode body 200 is held (supported) in a state of being suspended from the lid body 120 by the two current collectors 300. The material of the current collector 300 is not limited, but for example, the current collector 300 on the positive electrode side is made of a metal such as aluminum or an aluminum alloy, like the positive electrode base material layer of the electrode body 200. The current collector 300 on the negative electrode side is made of a metal such as copper or a copper alloy, like the negative electrode base material layer of the electrode body 200.

The upper gasket 140 is a member that is arranged between the lid 120 of the container 100 and the electrode terminal 130, and insulates and seals between the lid 120 and the electrode terminal 130. Specifically, the upper gasket 140 has a shape in which a through hole 140a into which the shaft portion 131 of the electrode terminal 130 is inserted is formed in the central portion of the rectangular substantially plate-shaped member, and the through hole 140a is formed. The upper gasket 140 is fixed to the lid 120 by inserting and caulking the shaft portion 131.

The lower gasket 150 is a member that is arranged between the lid 120 of the container 100 and the current collector 300, and insulates between the lid 120 and the current collector 300. Specifically, the lower gasket 150 has a shape in which a through hole 150a into which the shaft portion 131 of the electrode terminal 130 is inserted is formed in a substantially central portion of a rectangular substantially plate-shaped member. The lower gasket 150 is fixed to the lid 120 by inserting and crimping the shaft portion 131 into the 150a.

The upper gasket 140 and the lower gasket 150 are, for example, polypropylene (PP), polyethylene (PE), polyphenylene sulfide resin (PPS), polyethylene terephthalate (PET), polyetheretherketone (PEEK), tetrafluoroethylene / perfluoroalkyl. It is formed of an electrically insulating resin material such as vinyl ether (PFA), polytetrafluoroethylene (PTFE), polybutylene terephthalate (PBT), and poly ether sulfone (PES).

[2. Current collector configuration]
Next, the configuration of the current collector 300 according to the embodiment will be described with reference to FIGS. 4 to 7 in addition to FIGS. 2 and 3. In the present embodiment, since the pair of current collectors 300 arranged on the X-axis have a configuration common to each other, the present focus will be on the current collector 300 on the plus direction side of the X-axis (see FIG. 2). The illustration and explanation will be given.

FIG. 4 is a perspective view showing the configuration of the current collector 300 according to the embodiment. FIG. 5 is a view (side view) of the current collector 300 according to the embodiment as viewed from the Y-axis minus direction side. FIG. 6 is a view (rear view) when the current collector 300 according to the embodiment is viewed from the X-axis plus direction side. FIG. 7 is an enlarged perspective view showing an end portion of the current collector 300 according to the embodiment on the terminal connection portion 310 side.

As shown in FIGS. 4 to 7, the current collector 300 according to the embodiment has a terminal connection portion 310 formed in a substantially flat plate shape along an XY plane and a Y-axis erected from the terminal connection portion 310. It has a pair of legs 320 arranged in a direction. Since the pair of legs 320 have a structure common to each other, the following mainly describes one leg 320 of the pair of legs 320, but the description thereof is the other leg. It also applies to 320.

The leg portion 320 is erected from the terminal connecting portion 310 along the first direction (same as the Z-axis direction in the present embodiment) which is the alignment direction of the terminal connecting portion 310 and the electrode body 200, and is the Z axis. It is a long part in the direction. The leg portion 320 has a joint portion 330 formed in a predetermined range including, for example, a central portion in the longitudinal direction. Since the leg portion 320 is joined to the electrode body end portion 220 (see FIG. 3) at the joint portion 330, the electrode body 200 can be mechanically supported in a state of being electrically connected to the electrode body 200. can. That is, the current collector 300 is a long member in the Z-axis direction as a whole, and one end in the longitudinal direction is fixed to the container 100 to support the electrode body 200 in a cantilevered state in the container 100. are doing. Therefore, for example, when an impact is applied from the short side surface side (one side in the X-axis direction) of the power storage element 10, the leg portion 320 may be deformed in the X-axis direction by receiving the inertial force of the electrode body 200. .. More specifically, when a large inertial force is applied to the leg portion 320 and the amount of deformation of the leg portion 320 exceeds the elastic limit, plastic deformation occurs in the leg portion 320. If the leg portion 320 is plastically deformed, there arises a problem that causes an unsafe event such as damage to the electrode body 200 due to the leg portion 320.

However, in the current collector 300 according to the present embodiment, a high hardness portion 325 having a hardness higher than that of the terminal connecting portion 310 is formed on the leg portion 320. As a result, the deformation of the leg portion 320 due to the external force is suppressed, and as a result, the possibility of plastic deformation of the leg portion 320 is reduced.

That is, the power storage element 10 according to the present embodiment includes an electrode body 200, an electrode terminal 130, and a current collector 300 that electrically connects the electrode body 200 and the electrode terminal 130. The current collector 300 is connected to the electrode terminal 130 and stands along the Z-axis direction from the terminal connection portion 310 and the terminal connection portion 310 arranged at a position aligned with the electrode body 200 in the first direction (Z-axis direction). It has a leg portion 320 provided and joined to the electrode body 200. A high hardness portion 325 having a hardness higher than that of the terminal connection portion 310 is formed between the joint portion 330, which is a portion of the leg portion 320 that is joined to the electrode body 200, and the terminal connection portion 310.

As described above, in the present embodiment, the joint portion 330 on which the inertial force generated in the electrode body 200 directly acts when the power storage element 10 is impacted, and the terminal forming the fixed end of the current collector 300. A high hardness portion 325 having a hardness higher than that of the terminal connection portion 310 is provided between the connection portion 310 and the connection portion 310. Therefore, for example, the deformation of the leg portion 320 joined to the electrode body 200 can be effectively suppressed without modifying the leg portion 320, and as a result, the leg portion 320 can be plastically deformed. Plasticity is reduced. As a result, for example, the occurrence of a defect that the deformed leg portion 320 damages the electrode body 200 is reduced. As described above, according to the power storage element 10 according to this aspect, the deformation of the current collector 300 is suppressed, thereby improving the safety. In addition, "high hardness" can be rephrased as, for example, high yield strength. That is, a part of the leg portion 320 of the current collector 300 on the terminal connection portion 310 side is provided with a high hardness portion 325 which is a portion where plastic deformation is less likely to occur than the other portions, whereby the leg portion 320 is provided. Plastic deformation is suppressed. Further, the hardness of each of the terminal connection portion 310 and the high hardness portion 325 can be obtained by, for example, performing a predetermined measurement method (for example, Vickers hardness test) for each of the terminal connection portion 310 and the high hardness portion 325. can. This hardness may be an average value of hardness measured at a plurality of points.

Further, the hardness of the high hardness portion 325 does not have to be higher than all of the hardness measured at each of the plurality of locations of the terminal connection portion 310. That is, the hardness of the high hardness portion 325 may be equal to or lower than the hardness of a part of the terminal connection portion 310. For example, the terminal connection portion 310 is formed with a through hole 311 (see FIG. 3) into which the shaft portion 131 of the electrode terminal 130 is inserted, and the shaft portion 131 inserted into the through hole 311 is crimped. The shaft portion 131 and the terminal connection portion 310 are joined. In this case, in the terminal connection portion 310, work hardening occurs at the peripheral edge of the through hole 311 due to the caulking force, and as a result, the hardness of the peripheral edge of the through hole 311 may be equal to or higher than the hardness of the high hardness portion 325. Therefore, when the range covered by the caulking force of the peripheral edge of the through hole 311 of the terminal connection portion 310 is set as the caulking portion, the hardness of the high hardness portion 325 is the flat portion other than the caulking portion in the terminal connection portion 310 (FIG. It can also be explained that the hardness is higher than the hardness of the portion parallel to the XY plane in 4.

In the present embodiment, specifically, as shown in FIGS. 4 to 6, the tip portion (Z) of the leg portion 320 is formed from the portion between the joint portion 330 and the terminal connection portion 310 in the current collector 300. A high hardness portion 325 is formed in the range up to the end portion on the minus side of the shaft). Thereby, the deformation suppressing effect by the high hardness portion 325 can be obtained in a wide range in the leg portion 320.

Specifically, such a high hardness portion 325 is provided on the leg portion 320 as a portion formed thinner than the portion other than the high hardness portion 325 in the current collector 300. In the present embodiment, as shown in FIG. 7, the thickness of the high hardness portion 325 (average value of the flat portion) is Ta, and the thickness of the portion other than the high hardness portion 325 (average value of the flat portion) is Tb. If, then Ta <Tb. Further, Tb is about 0.6 mm to 2 mm. The ratio of Ta to Tb (Ta / Tb) is about 0.7 to 0.95, more preferably about 0.8 to 0.9.

That is, the high hardness portion 325 can be formed, for example, by work hardening by thinning a part of the metal plate which is the material of the current collector 300 by press working. Therefore, for example, a current collector 300 having a high hardness portion 325 can be easily manufactured by using a metal plate such as an aluminum alloy that is generally distributed. That is, the power storage element 10 with improved safety can be efficiently manufactured.

For example, it is conceivable to improve the rigidity of the leg portion 320 by giving the leg portion 320 of the current collector 300 a three-dimensional shape, thereby suppressing the deformation of the leg portion 320. However, as compared with the case where the leg portion 320 has a three-dimensional shape, the high hardness portion 325 according to this embodiment is advantageous in that it does not increase the size or weight of the current collector 300, or that complicated processing is not required. Is. Further, from the viewpoint of good bondability between the leg portion 320 and the electrode body end portion 220, the high hardness portion 325 that can be formed into a flat plate shape is more advantageous than the case where the leg portion 320 has a three-dimensional shape. Is.

Further, in the present embodiment, more specifically, the high hardness portion 325 is formed in a range including the end portion 322 on the terminal connection portion 310 side of the leg portion 320, as shown in FIGS. 4 to 7. ..

That is, when the joint portion 330 receives an external force, the high hardness portion 325 is formed in the range including the end portion 322 on the terminal connection portion 310 side where the stress is most likely to be concentrated in the leg portion 320. Therefore, the plastic deformation of the leg portion 320 can be suppressed more effectively, which further reduces the possibility of the leg portion 320 being plastically deformed.

Further, in the present embodiment, the leg portion 320 is divided into an end portion 322 located on the terminal connection portion 310 side and a leg portion main body 321 on which the joint portion 330 is formed, and the end portion 322 has a wide portion 323. Is provided, and a part of the high hardness portion 325 is formed in the wide portion 323. That is, the leg portion 320 is a leg portion main body 321 having a joint portion 330 and a wide portion 323 provided at the end portion 322, and is a thickness direction (Y-axis direction) and a first direction (Z) of the leg portion main body 321. It has a wide portion 323 in which the width in the second direction (X-axis direction) intersecting the axial direction becomes wider as it approaches the terminal connection portion 310. As shown in FIGS. 4 to 7, the high hardness portion 325 is formed in a region continuous with the leg main body 321 and the wide portion 323.

As described above, in the present embodiment, since the wide portion 323 is provided at the base portion of the leg portion 320 of the current collector 300, the leg portion 320 is deformed when the leg portion main body 321 receives an external force. It is suppressed. However, in this case, it is considered that the stress is concentrated on the boundary between the leg body 321 and the wide portion 323. Therefore, in the present embodiment, the high hardness portion 325 is provided so as to straddle the boundary between the leg portion main body 321 and the wide portion 323, which is a portion where stress is easily concentrated in this structure. As a result, the effect of suppressing the deformation of the leg portion 320 by the high hardness portion 325 is further improved, and as a result, the possibility of the leg portion 320 being plastically deformed is further reduced.

Further, in the present embodiment, in the current collector 300, a bent portion 340 formed in a curved shape is provided between the leg portion 320 and the terminal connecting portion 310 as shown in FIGS. 6 and 7. ing. The high hardness portion 325 is formed on the side of the electrode body 200 (that is, the Z-axis minus direction side) with respect to the bent portion 340 in the Z-axis direction.

The bent portion 340 is formed at the connection portion between the terminal connecting portion 310 and the leg portion 320, for example, by bending a plate-shaped member which is a material of the current collector 300. Therefore, since the high hardness portion 325 is formed avoiding the bent portion 340, the bending process for forming the bent portion 340 is not hindered by the high hardness portion 325. That is, it has a high hardness portion 325 that suppresses plastic deformation of the leg portion 320, and can efficiently perform a manufacturing process that involves bending. That is, the power storage element 10 with improved safety can be efficiently manufactured.

The bent portion 340 may not be formed in a curved shape, and may be formed in a bent shape, for example. Further, the bending portion 340 has a thickness direction of the connection portion between the terminal connection portion 310 and the leg portion 320 from the Z-axis direction (thickness direction of the terminal connection portion 310) to the Y-axis direction (thickness direction of the leg portion 320). It can also be expressed as a part that changes to.

Although the power storage element 10 according to the embodiment of the present invention has been described above, the power storage element 10 may include a current collector having a configuration different from the configurations shown in FIGS. 3 to 7. Therefore, a modified example of the configuration of the current collector will be described with reference to FIG. 8, focusing on the difference from the above embodiment.

[3. Modification example]
FIG. 8 is a perspective view showing the configuration of the current collector 300a according to the modified example of the embodiment. The current collector 300a shown in FIG. 8 is an example of a current collector that can be provided in the power storage element 10 in place of the current collector 300 according to the embodiment. The current collector 300a according to this modification is connected to the electrode terminal 130 (see FIG. 3), and is connected to the terminal connection portion 310a arranged at a position aligned with the electrode body 200 in the first direction (Z-axis direction). It has a leg portion 320a that is erected from the portion 310a along the Z-axis direction and is joined to the electrode body 200. A high hardness portion 325a having a hardness higher than that of the terminal connecting portion 310a is formed between the joining portion 330a, which is a portion of the leg portion 320a that is joined to the electrode body 200, and the terminal connecting portion 310a. Specifically, the high hardness portion 325a is provided on the leg portion 320a as a portion of the current collector 300a formed thinner than the portion other than the high hardness portion 325a. More specifically, the high hardness portion 325a is formed in a range including the end portion 322a on the terminal connection portion 310a side of the leg portion 320a.

That is, the current collector 300a according to the present modification has a configuration common to that of the current collector 300 according to the embodiment. Therefore, according to the current collector 300a according to the present modification, as in the current collector 300 according to the embodiment, for example, when an impact is applied to the power storage element 10, the legs joined to the electrode body 200 are joined. The deformation of the 320a is effectively suppressed, and as a result, the possibility of the leg portion 320a being plastically deformed is reduced. This improves the safety of the power storage element 10. Further, since the high hardness in the high hardness portion 325a can be realized by work hardening by, for example, thinning a part of the metal plate by press working, the power storage element 10 with improved safety can be efficiently manufactured. be able to. Further, the high hardness portion 325a is formed in a range including the end portion 322a on the terminal connecting portion 310a side in the leg portion 320a where stress is most likely to be concentrated. Therefore, the plastic deformation of the leg portion 320a can be suppressed more effectively, which further reduces the possibility of the leg portion 320a being plastically deformed.

That is, the current collector 300a according to the present modification has a shape different from that of the current collector 300 (see FIG. 4) according to the embodiment because it does not have a wide portion or the like. Further, the current collector 300a according to the present modification is different from the current collector 300 according to the embodiment, and the high hardness portion 325a is only above the joint portion 330a (on the terminal connection portion 310a side) in the leg portion 320a. Is formed in. However, the structural features of the leg portion 320a, such as the arrangement of the high hardness portion 325a between the joint portion 330a and the terminal connection portion 310a, are common to the current collector 300 according to the embodiment. .. Therefore, according to the current collector 300a according to the present modification, as described above, the deformation suppressing effect of the leg portion 320a can be obtained as in the current collector 300 according to the embodiment.

[4. Other variants]
Although the power storage element according to the embodiment of the present invention and the modified example thereof has been described above, the present invention is not limited to the embodiment and the modified example thereof. That is, it should be considered that the embodiments disclosed this time and examples thereof are exemplary in all respects and are not restrictive. The scope of the present invention is shown not by the above description but by the scope of claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of claims.

For example, the current collector 300 has two legs 320, but the number of legs 320 of the current collector 300 may be one or more. For example, even when the current collector 300 has only one leg 320, the leg 320 plays a role of electrical connection with the electrode body 200 and mechanical support of the electrode body 200. Can be done. Therefore, it is useful to provide the leg portion 320 with a high hardness portion 325 for suppressing deformation from the viewpoint of improving the safety of the power storage element 10.

Further, when the current collector 300 has a plurality of leg portions 320, at least one leg portion 320 may have a high hardness portion 325, whereby the at least one leg portion 320 having the high hardness portion 325 may be provided. Deformation is suppressed. As a result, as compared with the case where all the leg portions 320 do not have the high hardness portion 325, the occurrence of defects such as damage to the electrode body 200 when an impact is applied to the power storage element 10 is suppressed.

Further, it is not essential that the high hardness portion 325 is formed by work hardening. For example, at least a part of the high hardness portion 325 of the leg portion 320 may be made of a metal having a hardness higher than that of the metal constituting the terminal connection portion 310. For example, a high hardness portion 325 may be provided by joining a base material of the current collector 300, which is made of an aluminum alloy or the like, with steel having a hardness higher than that of the base material by diffusion bonding, brazing, or the like. ..

Further, the type of the electrode body included in the power storage element 10 is not limited to the winding type. For example, the power storage element 10 is provided with a laminated electrode body in which flat plate-shaped electrode plates are laminated, or an electrode body having a structure in which long strip-shaped electrode plates are laminated in a bellows shape by repeating mountain folds and valley folds. May be done.

Further, the power storage element 10 does not have to include the current collector 300 having the high hardness portion 325 on both the positive electrode side and the negative electrode side. The power storage element 10 may be provided with a current collector 300 on one of the positive electrode side and the negative electrode side, and may be provided on the other side with a current collector having no high hardness portion 325.

Further, various supplementary items regarding the current collector 300 according to the embodiment described above may be applied to the current collector 300a according to a modified example. Further, a form constructed by arbitrarily combining the components included in the above-described embodiment and its modifications is also included in the scope of the present invention. Further, the present invention can be realized not only as such a power storage element but also as a current collector included in the power storage element.

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

10 Power storage element 130 Electrode terminal 200 Electrode body 210 Electrode body body 220 Electrode body end 300, 300a Collector 310, 310a Terminal connection 320, 320a Leg 321 Leg body 322, 322a End 323 Wide part 325, 325a High hardness part 330, 330a Joint part 340 Bending part

Claims (5)

A power storage element including an electrode body, an electrode terminal, and a current collector for electrically connecting the electrode body and the electrode terminal.
The current collector
A terminal connection portion connected to the electrode terminal and arranged at a position aligned with the electrode body in the first direction,
It has a leg portion that is erected from the terminal connection portion along the first direction and is joined to the electrode body.
A high hardness portion having a hardness higher than that of the terminal connection portion is formed between the joint portion of the leg portion, which is a portion joined to the electrode body, and the terminal connection portion.
Power storage element. The high hardness portion is formed in a range including the end portion of the leg portion on the terminal connection portion side.
The power storage element according to claim 1. The legs
With the leg body having the joint,
It has a wide portion provided at the end portion, wherein the width in the thickness direction of the leg body and the width in the second direction intersecting the first direction becomes wider as it approaches the terminal connection portion. ,
The high hardness portion is formed in a region continuous with the leg body and the wide portion.
The power storage element according to claim 2. In the current collector, the connecting portion between the leg portion and the terminal connecting portion is provided with a bent portion formed in a curved or bent shape.
The high hardness portion is formed on the side of the electrode body with respect to the bent portion in the first direction.
The power storage element according to any one of claims 1 to 3. The high-hardness portion is formed thinner than the portion other than the high-hardness portion in the current collector.
The power storage element according to any one of claims 1 to 4.

Images