JP2021120961A - Square secondary battery and battery pack using the same - Google Patents

Abstract

To provide a square secondary battery of a high capacity that has a high volume energy density.SOLUTION: A flat wound electrode body 3 in which a positive electrode plate and a negative electrode plate are wound with a separator interposed therebetween has a positive electrode tab portion 4c and a negative electrode tab portion 5c at one end portion in an extension direction of the winding axis. Two flat wound electrode bodies 3 are arranged so that the winding axes thereof are perpendicular to a sealing plate 2, and housed in a square exterior package body 1 so that the positive electrode tab portion 4c and the negative electrode tab portion 5c are positioned on the side of the sealing plate 2.SELECTED DRAWING: Figure 3

Description

The present invention relates to a square secondary battery and an assembled battery using the same.

Secondary batteries such as alkaline secondary batteries and non-aqueous electrolyte secondary batteries are used in driving power sources for electric vehicles (EVs) and hybrid electric vehicles (HEVs, PHEVs). Since high capacity or high output characteristics are required in these applications, it is used as an assembled battery in which a large number of square secondary batteries are connected in series or in parallel.

In these square secondary batteries, a battery case is formed by a bottomed tubular square exterior body having an opening and a sealing plate that seals the opening. An electrode body composed of a positive electrode plate, a negative electrode plate, and a separator is housed in the battery case together with the electrolytic solution. A positive electrode terminal and a negative electrode terminal are fixed to the sealing plate. The positive electrode terminal is electrically connected to the positive electrode plate via the positive electrode current collector, and the negative electrode terminal is electrically connected to the negative electrode plate via the negative electrode current collector.

The positive electrode plate includes a metal positive electrode core and a positive electrode active material layer formed on the surface of the positive electrode core. An exposed portion of the positive electrode core body from which the positive electrode active material layer is not formed is formed on a part of the positive electrode core body. Then, the positive electrode current collector is connected to the exposed portion of the positive electrode core. Further, the negative electrode plate includes a metal negative electrode core body and a negative electrode active material layer formed on the surface of the negative electrode core body. An exposed portion of the negative electrode core body from which the negative electrode active material layer is not formed is formed on a part of the negative electrode core body. Then, the negative electrode current collector is connected to the exposed portion of the negative electrode core.

For example, in Patent Document 1, a square rechargeable battery using a wound electrode body having a positive electrode core body exposed portion wound around one end and a negative electrode core body exposed portion wound around the other end. The next battery has been proposed. Further, Patent Document 2 proposes a square secondary battery using a wound electrode body provided with a positive electrode core body exposed portion and a negative electrode core body exposed portion at one end.

Japanese Unexamined Patent Publication No. 2009-032640 Japanese Unexamined Patent Publication No. 2008-226625

With respect to in-vehicle secondary batteries, particularly secondary batteries used for EVs, PHEVs, etc., it is required to develop a secondary battery having a higher volumetric energy density and a larger battery capacity. In the case of the square secondary battery disclosed in Patent Document 1, the space on the left and right where the wound positive electrode core body exposed portion and the wound negative electrode core body exposed portion are arranged, and An upper space is required between the sealing plate and the wound electrode body, which causes difficulty in increasing the volumetric energy density of the secondary battery.

On the other hand, like the square secondary battery disclosed in Patent Document 2, a wound electrode body having a positive electrode core body exposed portion and a negative electrode core body exposed portion provided at one end thereof is used. It becomes easy to obtain a square secondary battery with high energy density.

However, in the square secondary battery disclosed in Patent Document 2, the structure of the current collector tends to be more complicated than in the square secondary battery disclosed in Patent Document 1.

An object of the present invention is to provide a high-capacity square secondary battery having a high volumetric energy density and an assembled battery using the same.

The square secondary battery according to one embodiment of the present invention has a flat wound electrode body in which a positive electrode plate and a negative electrode plate are wound via a separator, and an opening, and houses the wound electrode body. A square exterior body, a sealing plate that seals the opening, a positive electrode terminal that is electrically connected to the positive electrode plate and attached to the sealing plate, and a positive electrode that electrically connects the positive electrode plate and the positive electrode terminal. A square secondary having a current collector, a negative electrode terminal electrically connected to the negative electrode plate and attached to the sealing plate, and a negative electrode current collector electrically connecting the negative electrode plate and the negative electrode terminal. In a battery, the wound electrode body has a positive electrode tab portion and a negative electrode tab portion at one end in a direction in which the winding shaft of the wound electrode body extends, and at least two of the wound electrode bodies. However, each of the winding shafts is arranged in a direction perpendicular to the sealing plate, and the positive electrode tab portion and the negative electrode tab portion are housed in the square exterior body so as to be located on the sealing plate side. The positive electrode plate is independent for each wound electrode body, and the negative electrode plate is independent for each wound electrode body. The joint between the positive electrode current collector and the positive electrode terminal is displaced in the longitudinal direction of the sealing plate, and the sealing plate and the wound electrode body are displaced in the direction facing each other. Alternatively, the joint portion between the negative electrode tab portion and the negative electrode current collector and the joint portion between the negative electrode current collector and the negative electrode terminal are displaced in the longitudinal direction of the sealing plate, and the sealing plate and the winding It is displaced in the direction facing the rotating electrode body.

According to such a configuration, a flat wound electrode body having a positive electrode tab portion and a negative electrode tab portion formed on one end side in the direction in which the winding shaft extends is used, and the positive electrode tab portion and the negative electrode tab portion are sealed plates. By arranging it on the side, it is possible to reduce the space in the battery case that is not involved in power generation. Therefore, a square secondary battery having a higher volumetric energy density and a larger battery capacity can be obtained.

Further, by using a plurality of flat wound electrode bodies housed in the square exterior body, the connection portion between the positive electrode tab portion and the positive electrode current collector and the connection portion between the negative electrode tab portion and the negative electrode current collector can be formed. It is possible to make a simpler configuration.

It is also possible to combine the positive electrode current collector and the positive electrode terminal into one component. It is also possible to combine the negative electrode current collector and the negative electrode terminal into one component. Further, the positive electrode current collector and the positive electrode terminal may be electrically connected via another conductive member. The negative electrode current collector and the positive electrode terminal may be electrically connected via another conductive member.

The square exterior body has a bottom, a pair of large area side walls, and a pair of small area side walls.
The area of the small area side wall is smaller than the area of the large area side wall.
The area of the bottom is preferably smaller than the area of the small side wall.

According to such a configuration, of the six outer surfaces of the battery case formed by the square exterior body and the sealing plate, the bottom surface and the sealing plate surface have a smaller area than the other four surfaces. Therefore, it is possible to reduce the space formed between the wound electrode body and the sealing plate and where the positive electrode tab portion, the negative electrode tab portion, the positive electrode electric body, the negative electrode current collector, and the like are arranged. Therefore, the square secondary battery has a higher volumetric energy density.

The positive electrode plate has a positive electrode core body and a positive electrode active material layer formed on the positive electrode core body, and the positive electrode core body has a positive electrode core body exposed portion on which the positive electrode active material layer is not formed. The negative electrode plate has a negative electrode core body and a negative electrode active material layer formed on the negative electrode core body, and the negative electrode core body has a negative electrode core body exposed portion on which the negative electrode active material layer is not formed. However, it is preferable that the positive electrode tab portion is the positive electrode core exposed portion and the negative electrode tab portion is the negative electrode core exposed portion.

The positive electrode tab portion is preferably composed of a positive electrode core body. Further, it is preferable that the negative tab portion is composed of a negative core body. The positive electrode tab portion and the negative electrode tab portion may be different parts from the core body connected to the positive electrode core body or the negative electrode core body, respectively. For example, a metal plate made of aluminum, aluminum alloy, copper, copper alloy, nickel, nickel alloy, or the like can be used as the tab portion.

It is preferable that the positive electrode tab portion has a straight portion and a curved portion, and the negative electrode tab portion has a straight portion and a curved portion.

It is preferable that the positive electrode tabs having substantially the same width are formed at substantially equal intervals at one end of the positive electrode plate in the width direction.

The width of the positive electrode tab portion means the width of the positive electrode tab portion along the longitudinal direction of the positive electrode plate in the unfolded state of the positive electrode plate. Further, the distance between the positive electrode tab portions means the distance between the positive electrode tab portions along the longitudinal direction of the positive electrode plate in the unfolded state of the positive electrode plate. The substantially same width means that the width of each positive electrode tab portion is within the range of plus or minus 10%. It is preferable that the width of each positive electrode tab portion is within the range of plus or minus 5%. Further, the substantially equal interval means that the interval between the positive electrode tab portions is within the range of plus or minus 10%. It is preferable that the distance between the positive electrode tab portions is within the range of plus or minus 5% of the width of each positive electrode tab portion.

According to such a configuration, the charge / discharge reaction in the positive electrode plate becomes more uniform. Moreover, the positive electrode plate can be easily manufactured.

The width of the positive electrode tab portion is preferably 1/4 or more and 1/2 or less of the width of the wound electrode body.

Here, the width of the wound electrode body is a width in a direction perpendicular to the winding axis and perpendicular to the thickness direction of the wound electrode body.

By stacking the positive electrode tabs in a detached state, a positive electrode stepped portion formed by the ends of the positive electrode tabs is formed.
It is preferable that the positive electrode current collector is connected to the positive electrode stepped portion.

It is preferable that the negative electrode tabs having substantially the same width are formed at substantially equal intervals at one end of the negative electrode plate in the width direction.

The width of the negative electrode tab portion means the width of the negative electrode tab portion along the longitudinal direction of the negative electrode plate in the unfolded state of the negative electrode plate. Further, the distance between the negative electrode tab portions means the distance between the negative electrode tab portions along the longitudinal direction of the negative electrode plate in the unfolded state of the negative electrode plate. The substantially same width means that the width of each negative electrode tab portion is within the range of plus or minus 10%. It is preferable that the width of each negative electrode tab portion is within the range of plus or minus 5%. Further, the substantially equal spacing means that the spacing between the negative electrode tabs is within the range of plus or minus 10%. It is preferable that the distance between the negative electrode tab portions is within the range of plus or minus 5% of the width of each negative electrode tab portion.

According to such a configuration, the charge / discharge reaction in the negative electrode plate becomes more uniform. Moreover, the negative electrode plate can be easily manufactured.

The width of the negative electrode tab portion is preferably 1/4 or more and 1/2 or less of the width of the wound electrode body.

By stacking the negative electrode tabs in a detached state, a negative electrode stepped portion formed by the ends of the negative electrode tabs is formed.
It is preferable that the negative electrode current collector is connected to the negative electrode stepped portion.

The assembled battery according to one embodiment of the present invention is
With the plurality of the square secondary batteries
With a pair of end plates
It has a bind bar that connects the pair of end plates, and
The plurality of square secondary batteries are stacked between the pair of end plates so that their large-area side walls are parallel to each other.
The positive electrode terminal and the negative electrode terminal of each of the square secondary batteries are arranged on one side surface.
On the other side surface, the bottom surface of each of the square exterior bodies of each of the square secondary batteries is arranged.

According to the present invention, it is possible to provide a high-capacity square secondary battery having a high volumetric energy density and an assembled battery using the same.

It is a perspective view of the square secondary battery which concerns on embodiment. It is sectional drawing along the line II-II of FIG. FIG. 3 is a cross-sectional view taken along the line III-III of FIG. It is sectional drawing along the IV-IV line of FIG. It is sectional drawing along the VV line of FIG. It is a top view of the positive electrode plate which concerns on embodiment. It is a top view of the negative electrode plate which concerns on embodiment. It is a figure which looked at the winding electrode body which concerns on embodiment along the direction which the winding shaft extends. It is a perspective view of a current collector. It is a figure which shows the connection process of a tab part and a current collector. It is a figure which shows the connection part of a tab part and a current collector. It is a figure of the wound electrode body used for the square secondary battery which concerns on a reference example. It is a figure of the wound electrode body used for the square secondary battery which concerns on embodiment. It is a perspective view of the current collector of a modification. It is a perspective view of the current collector of a modification. It is a perspective view of the current collector of a modification. It is a perspective view of the current collector of a modification. It is a figure which shows the connection process of the tab part and the current collector in the square secondary battery of a modification. It is a figure which shows the connection process of the tab part and the current collector in the square secondary battery of a modification. It is a top view of the positive electrode plate and the negative electrode plate which concerns on a modification. It is a figure which shows the winding electrode body which concerns on the modification. It is sectional drawing of the current cutoff mechanism of the square secondary battery which concerns on the modification. It is a perspective view of the current collector used for a current cutoff mechanism. It is a perspective view of the assembled battery which concerns on embodiment.

The configuration of the square secondary battery 20 according to the embodiment will be described below. The present invention is not limited to the following embodiments.
As shown in FIGS. 1 to 5, the square secondary battery 20 includes a square exterior body 1 having an opening and a sealing plate 2 for sealing the opening. The battery case is composed of the square exterior body 1 and the sealing plate 2. The square exterior body 1 and the sealing plate 2 are preferably made of metal, and can be made of, for example, aluminum or an aluminum alloy. The square exterior body 1 has a bottom portion 1a, a pair of large-area side walls 1b, and a pair of small-area side walls 1c. The square exterior body 1 is a square bottomed tubular exterior body having an opening at a position facing the bottom. Inside the square exterior body 1, a flat wound electrode body 3 in which a positive electrode plate and a negative electrode plate are wound via a separator (both not shown) is housed together with an electrolyte. In the positive electrode plate, a positive electrode active material layer containing a positive electrode active material is formed on a metal positive electrode core body. At the end in the width direction of the positive electrode plate, a positive electrode core body exposed portion 4b is formed so that the positive electrode core body is exposed. It is preferable to use an aluminum foil or an aluminum alloy foil as the positive electrode core. In the negative electrode plate, a negative electrode active material layer containing a negative electrode active material is formed on a metal negative electrode core body. A negative electrode core body exposed portion 5b is formed at the end portion in the width direction of the negative electrode plate so that the negative electrode core body is exposed. It is preferable to use a copper foil or a copper alloy foil as the negative electrode core. In the square secondary battery 20, the positive electrode core body exposed portion 4b constitutes the positive electrode tab portion 4c, and the negative electrode core body exposed portion 5b constitutes the negative electrode tab portion 5c.

As shown in FIGS. 2 to 4, two flat wound electrode bodies 3 are arranged on the square exterior body 1 so that the direction in which the winding axis extends is perpendicular to the sealing plate 2. ing. The positive electrode core body exposed portion 4b and the negative electrode core body exposed portion 5b of each wound electrode body 3 are located on the sealing plate 2 side. Further, the positive electrode core body exposed portions 4b of each wound electrode body 3 are located on the same side (upper side in FIG. 2), and the negative electrode core body exposed portions 5b of each wound electrode body 3 are on the same side (lower side in FIG. 2). ) Is located.

A laminated positive electrode core body exposed portion 4b and a laminated negative electrode core body exposed portion 5b are provided on one end side of the wound electrode body 3 in the direction in which the winding shaft extends. The positive electrode current collector 6 is welded to the laminated positive electrode core body exposed portion 4b to form the welded portion 30. Then, the positive electrode terminal 7 is electrically connected to the positive electrode current collector 6. The negative electrode current collector 8 is welded to the laminated negative electrode core body exposed portion 5b to form the welded portion 30. Then, the negative electrode terminal 9 is electrically connected to the negative electrode current collector 8.

The positive electrode terminal 7 and the positive electrode current collector 6 are fixed to the sealing plate 2 via the insulating member 10 and the gasket 11, respectively. The negative electrode terminal 9 and the negative electrode current collector 8 are fixed to the sealing plate 2 via the insulating member 12 and the gasket 13, respectively. The gaskets 11 and 13 are arranged between the sealing plate 2 and the terminals 7 and 9, respectively. The insulating members 10 and 12 are arranged between the sealing plate 2 and the current collectors 6 and 8, respectively. It is preferable that the gasket and the insulating member are each made of an insulating resin member. The wound electrode body 3 is housed in the square exterior body 1 in a state of being covered with a box-shaped bent insulating sheet 14. The insulating sheet 14 covers the wound electrode body 3 and is arranged between the wound electrode body 3 and the square exterior body 1. The sealing plate 2 is welded and connected to the opening edge of the square exterior body 1 by laser welding or the like. The sealing plate 2 has an electrolytic solution injection hole 15, and the electrolytic solution injection hole 15 is sealed by a sealing plug 16 after injection. The sealing plate 2 is formed with a gas discharge valve 17 for discharging gas when the pressure inside the battery becomes high.

The size of the square secondary battery 20 is, for example, a width (length in the direction perpendicular to the sealing plate 2; length in the left-right direction in FIG. 1) of 18 cm and a thickness (length in the front-rear direction in FIG. 1). The length is 3 cm, and the height (length parallel to the sealing plate 2 and perpendicular to the thickness direction of the square secondary battery 20; length in the vertical direction in FIG. 1) is 9 cm. Can be done.

The present invention is particularly effective when the ratio of the width to the height of the square secondary battery is 2 or more. The present invention is particularly effective when the height of the square secondary battery is 10 cm or less and the width of the square secondary battery is 17 cm or more. Further, the present invention is particularly effective when the battery capacity is 30 Ah or more. The value of the battery capacity can be a design capacity, that is, a value of a nominal capacity specified by the battery manufacturer.

The following method of manufacturing the square secondary battery 20 will be described.

[Manufacturing of positive electrode plate]
A positive electrode slurry containing lithium cobalt oxide as a positive electrode active material, polyvinylidene fluoride (PVdF) as a binder, a carbon material as a conductive material, and N-methylpyrrolidone (NMP) is prepared. This positive electrode slurry is applied to both sides of a rectangular aluminum foil having a thickness of 15 μm, which is a positive electrode core. Then, by drying this, N-methylpyrrolidone in the positive electrode slurry is removed, and a positive electrode active material layer is formed on the positive electrode core body. Then, the positive electrode active material layer is compressed so as to have a predetermined thickness. The positive electrode plate thus obtained is cut so that exposed portions of the positive electrode core having a predetermined width are formed at one end in the width direction at predetermined intervals.

As shown in FIG. 6, in the positive electrode plate 4 thus obtained, the positive electrode active material layer 4a is formed on the positive electrode core body. Then, positive electrode core body exposed portions 4b having a predetermined width are formed at one end in the width direction at predetermined intervals. The exposed positive electrode core body 4b constitutes the positive electrode tab portion 4c.

Here, the width W1 of each positive electrode tab portion 4c is set to 40 mm. Further, the distance W2 between the positive electrode tab portions 4c is set to 120 mm. The width W1 of the positive electrode tab portion 4c is the width of the positive electrode plate in the longitudinal direction.

[Manufacturing of negative electrode plate]
A negative electrode slurry containing graphite as a negative electrode active material, styrene-butadiene rubber (SBR) as a binder, carboxymethyl cellulose (CMC) as a thickener, and water is prepared. This negative electrode slurry is applied to both sides of a rectangular copper foil having a thickness of 8 μm, which is a negative electrode core. Then, by drying this, water in the negative electrode slurry is removed, and a negative electrode active material layer is formed on the negative electrode body. After that, the negative electrode active material layer is compressed so as to have a predetermined thickness. The negative electrode plate thus obtained is cut so that exposed negative electrode core bodies having a predetermined width are formed at one end in the width direction at predetermined intervals.

As shown in FIG. 7, in the negative electrode plate 5 thus obtained, the negative electrode active material layer 5a is formed on the negative electrode core body. A negative electrode core body exposed portion 5b having a predetermined width is formed at one end in the width direction at a predetermined interval. The exposed negative electrode core 5b constitutes the negative electrode tab portion 5c. In the negative electrode plate 5, a negative electrode core body exposed portion 5b is also formed at the other end portion in the width direction.

Here, the width W3 of each negative electrode tab portion 5c is set to 40 mm. Further, the distance W4 between the negative electrode tab portions 5c is set to 120 mm. The width W3 of the negative electrode tab portion is the width of the negative electrode plate 5 in the longitudinal direction.

The relationship between the width W1 of the positive electrode tab portion 4c, the distance W2 between the positive electrode tab portions 4c, the length L of the straight portion of the wound electrode body 3, and the radius R of the curved portion of the wound electrode body 3 is W1 + W2> 2L. Is preferable. Further, when W1 + 2πR <L and the winding start position of the positive electrode plate is 0 °, it is preferable that the winding start position of the negative electrode plate is 180 to 270 °.

The relationship between the width W2 of the negative electrode tab portion 5c, the distance W4 between the negative electrode tab portions 5c, the length L of the straight portion of the wound electrode body 3, and the radius R of the curved portion of the wound electrode body 3 is W3 + W4> 2L. Is preferable.

[Wound electrode body]
The positive electrode plate 4 and the negative electrode plate 5 obtained by the above method are shifted so that the positive electrode tab portion 4c and the negative electrode tab portion 5c do not overlap, and the porous separator made of polyethylene is interposed between them to laminate and wind the positive electrode plate 4 and the negative electrode plate 5. By pressing, it becomes a flat wound electrode body 3.

FIG. 8 is a diagram showing a surface of the wound electrode body 3 on the side where the positive electrode tab 4c and the negative electrode tab 5c are formed. As shown in FIG. 8, in the wound electrode body 3, the positive electrode tab portion 4c and the negative electrode tab portion 5c are arranged on one end side in the direction in which the winding shaft extends. Then, the positive electrode tab 4c is laminated on one side in the width direction (the direction perpendicular to the direction in which the winding axis of the wound electrode body 3 extends and the direction perpendicular to the thickness direction of the wound electrode body 3). The negative electrode tab portion 5c is laminated on the other side.

The positive electrode tab portion 4c and the negative electrode tab portion 5c are a straight portion 31 arranged in a straight portion (flat end portion) of the wound electrode body 3 and a curved portion arranged in a curved portion (curved portion) of the wound electrode body 3, respectively. It has 32. Further, the positive electrode tab portions 4c are arranged and laminated so as to be slightly displaced from the beginning of winding to the end of winding. Further, each negative electrode tab portion 5c is also arranged and laminated so as to be slightly displaced from the beginning to the end of winding. Therefore, the laminated positive electrode tab portions 4c are formed with stepped portions 33 formed by the ends of the positive electrode tab portions 4c. Further, the laminated negative electrode tab portions 5c are formed with stepped portions 33 formed by the ends of the negative electrode tab portions 5c.

Two wound electrode bodies 3 produced in this manner are prepared, and the positive electrode tab portion 4c and the negative electrode tab portion 5c are arranged on the same side, respectively, and the two wound electrode bodies 3 are provided with insulating tape. Are fixed together. It should be noted that at least two wound electrode bodies 3 may be used, and the number thereof is not particularly limited. Further, the plurality of wound electrode bodies 3 do not necessarily have to be fixed, but are preferably fixed together. The fixing method is not particularly limited, and it may be fixed with an insulating tape, or it may be put together by arranging it in a bag-shaped or box-shaped insulating sheet.

[Assembly of sealing plate, current collector and terminals]
As shown in FIGS. 1 and 2, a gasket 11 is arranged on the outer side of the battery of the sealing plate 2 and an insulating member 10 is arranged on the inner side of the battery of the sealing plate 2 on one end side in the longitudinal direction of the sealing plate 2. The positive electrode terminal 7 has a flange portion 7a and an insertion portion 7b. The positive electrode terminal 7 is arranged on the gasket 11, and the positive electrode current collector 6 is arranged on the lower surface of the insulating member 10. Through holes are formed in the gasket 11, the sealing plate 2, the insulating member 10, and the positive electrode current collector 6, respectively. The positive electrode terminal 7 is inserted into these through holes from the outside of the battery, and the tip of the positive electrode terminal 7 is added. By tightening, the positive electrode terminal 7, the gasket 11, the sealing plate 2, the insulating member 10, and the positive electrode current collector 6 are integrally fixed. It is preferable that the crimped portion of the positive electrode terminal 7 and the positive electrode current collector 6 are welded by laser welding or the like.

On the other end side of the sealing plate 2 in the longitudinal direction, the gasket 13 is arranged on the outer side of the battery of the sealing plate 2, and the insulating member 12 is arranged on the inner side of the battery of the sealing plate 2. The negative electrode terminal 9 has a flange portion 9a and an insertion portion 9b. The negative electrode terminal 9 is arranged on the gasket 13, and the negative electrode current collector 8 is arranged on the lower surface of the insulating member 12. Through holes are formed in the gasket 13, the sealing plate 2, the insulating member 12, and the negative electrode current collector 8, respectively. The negative electrode terminal 9 is inserted into these through holes from the outside of the battery, and the tip of the negative electrode terminal 9 is added. By tightening, the negative electrode terminal 9, the gasket 13, the sealing plate 2, the insulating member 12, and the negative electrode current collector 8 are integrally fixed. It is preferable that the crimped portion of the negative electrode terminal 9 and the negative electrode current collector 8 are welded by laser welding or the like.

The positive electrode current collector 6 and the negative electrode current collector 8 shown in FIG. 9 are used. The positive electrode current collector 6 will be described as an example. The positive electrode current collector 6 has a base portion 6a to which the positive electrode terminal 7 is connected, and a connecting portion 6b extending from the end portion of the base portion 6a in the direction of the wound electrode body 3. A through hole 6c is formed in the base portion 6a. The positive electrode terminal 7 is inserted into the through hole 6c, and the tip of the positive electrode terminal 7 is crimped onto the base portion 6a to connect the positive electrode terminal 7 and the positive electrode current collector 6. The connecting portions 6b are provided at both ends of the base portion 6a in the thickness direction of the battery (front end and back end in FIG. 9). A protrusion 34 is formed on the connecting portion 6b. Further, a slit 35 is formed in the connecting portion 6b. The negative electrode current collector 8 can also have the same shape as the positive electrode current collector 6. The positive electrode current collector 6 and the negative electrode current collector 8 are preferably formed by bending a plate-shaped metal member.

[Connection between current collector and wound electrode body]
FIG. 10 is a diagram showing a connection process between the tab portion and the current collector, and is a cross-sectional view corresponding to FIGS. 2 and 3. As shown in FIG. 10, the positive electrode tab portion 4c laminated on the protrusion 34 formed on the connecting portion 6b of the positive electrode current collector 6 is arranged on each of the one side surface side and the other side surface side. Then, resistance welding is performed by passing a resistance welding current in a state where the laminated positive electrode tab portion 4c and the positive electrode current collector 6 are sandwiched between the pair of resistance welding electrodes 40. As a result, the laminated positive electrode tab portion 4c and the positive electrode current collector 6 are welded and connected. On the negative electrode side, the negative electrode tab portion 5c and the negative electrode current collector 8 are welded and connected in the same manner.

When the positive electrode current collector 6 or the negative electrode current collector 8 shown in FIG. 9 is used, first, the portions where the protrusions 34 on the front and back sides of FIG. 9 are formed are welded and connected by the method shown in FIG. conduct. After that, the portions where the protrusions 34 on the front and back sides on the right side of FIG. 9 are formed are welded and connected by the method shown in FIG. At this time, as shown in FIG. 9, since the slit 35 is formed in the connecting portion 6b, it is invalid to pass through the first welded portion that has already been resistance welded at the time of the second resistance welding. It is possible to suppress the generation of an electric current (current that is not involved in resistance welding). The order of resistance welding may be either the left side or the right side in FIG. 9 first, or may be performed at the same time. The same method can be applied to the negative electrode side.

Further, as shown in FIG. 11, the positive electrode current collector 6 can be welded and connected to the stepped portion 33 of the positive electrode tab portion 4c. As a result, not only the positive electrode tab portion 4c located on the outermost periphery of the wound electrode body 3 but also the positive electrode tab portion 4c located on the inner peripheral side of the wound electrode body 3 can be firmly connected by the positive electrode current collector 6. Further, not only the positive electrode tab portion 4c located on the outermost periphery of the wound electrode body 3 but also the positive electrode tab portion 4c located on the inner peripheral side of the wound electrode body 3 is welded at a position close to the positive electrode current collector 6. .. Therefore, it is possible to collect current more uniformly. The same method can be applied to the negative electrode side.

Next, the wound electrode body 3 connected to the positive electrode current collector 6 and the negative electrode current collector 8 is inserted into the square exterior body 1 in a state of being arranged in the insulating sheet 14 bent in a box shape. The insulating sheet 14 includes a region extending in the direction in which the wound electrode bodies 3 are arranged and having a surface facing the side wall of the square exterior body 1. Then, the joint portion between the sealing plate 2 and the square exterior body 1 is welded by laser welding, and the opening of the square exterior body 1 is sealed. After that, the non-aqueous electrolytic solution is injected from the electrolytic solution injection hole 15 provided in the sealing plate 2, and the electrolytic solution injection hole 15 is sealed by the sealing plug 16 to manufacture a square secondary battery 20.

In the square secondary battery 20, in the wound electrode body 3, the positive electrode tab portion 4c and the negative electrode tab portion 5c are arranged on the sealing plate 2 side, respectively. Therefore, the space in which the members not involved in power generation are arranged in the square exterior body 1 can be reduced, and the square secondary battery has a high volume energy density. Further, in the square secondary battery 20, the sealing plate 2 is arranged on the surface having the smallest area among the six surfaces of the battery case composed of the square exterior body 1 and the sealing plate 2. That is, the area of the bottom portion 1a of the sealing plate 2 and the square exterior body 1 is smaller than the four side walls of the square exterior body 1 (a pair of large area side walls 1b and a pair of small area side walls 1c). As a result, the space in which the members not involved in power generation are arranged can be minimized, and the battery has a higher volume energy density.

Further, in the square secondary battery 20, the electrode bodies housed in the square exterior body 1 are a plurality of flat wound electrode bodies 3.

When manufacturing a square secondary battery having a large capacity (for example, a battery capacity of 30 Ah or more), when the electrode body housed in the square exterior body 1 is one wound electrode body, the wound electrode body is shown in FIG. As shown, the wound electrode body has a large number of turns and a large thickness. In such a wound electrode body, it is difficult to align the positive electrode tab portions 4c with each other and the negative electrode tab portions 5c with each other, and it is also difficult to increase the width of each positive electrode tab portion 4c and each negative electrode tab portion 5c. Is. In addition, the positive electrode tab portion 4c and the negative electrode tab portion 5c may easily come into contact with each other. Further, it becomes difficult to connect the positive electrode tab portion 4c and the positive electrode current collector 6 and the negative electrode tab portion 5c and the negative electrode current collector 8.

On the other hand, by using a plurality of flat wound electrode bodies 3 as the electrode bodies housed in the square exterior body 1, it becomes easy to align the positive electrode tab portions 4c with each other and the negative electrode tab portions 5c with each other. .. Further, even if the width of each positive electrode tab portion 4c and each negative electrode tab portion 5c is increased, contact between the positive electrode tab portion 4c and the negative electrode tab portion 5c can be easily prevented (see FIG. 13). Therefore, like the square secondary battery 20, the electrode body housed in the square exterior body 1 is divided into a plurality of electrodes to prevent contact between the positive electrode tab portion 4c and the negative electrode tab portion 5c, while preventing the positive electrode tab portion 4c and the negative electrode tab portion 5c from coming into contact with each other. By increasing the widths of the 4c and the negative electrode tab portion 5c, the current collection efficiency is improved, and further, it is possible to prevent the positive electrode tab portion 4c or the negative electrode tab portion 5c from being damaged or damaged due to vibration or the like. Therefore, a square secondary battery having excellent current collection efficiency and high reliability can be obtained.

<Modification example 1>
FIG. 14 shows a current collector according to the first modification. In the positive electrode current collector 6 (negative electrode current collector 8), the protrusion 34 provided on the connecting portion 6b (8b) can be a linear protrusion extending in the lateral direction. With such a configuration, it is possible to allow the resistance welding electrode 40 to be displaced with respect to the protrusion 34 during welding. Therefore, the current collecting structure is more productive and has excellent welding quality.

<Modification 2>
FIG. 15 shows a current collector according to the second modification. In the positive electrode current collector 6 (negative electrode current collector 8), the portion where the welded portion is formed may be one on the front side and one on the back side, respectively. Further, the protrusion 34 may be point-shaped (square, circular, hemispherical, etc.). Further, the base portion 6a (8a) is smaller than the wide portion 6a1 (8a1) having a large width in the thickness direction of the square secondary battery 20 and the wide portion 6a1 (8a1) having a width in the thickness direction of the square secondary battery 20. It has a narrow portion 6a2 (8a2). The positive electrode terminal 7 (negative electrode terminal 9) is connected to the wide portion 6a1 (8a1). Further, the connecting portion 6b (8b) is formed at the end portion of the narrow portion 6a2 (8a2). With such a configuration, in the base portion 6a (8a), the portion to which the positive electrode terminal 7 (negative electrode terminal 9) is connected can be widened, so that the positive electrode terminal 7 (negative electrode terminal) is connected to the base portion 6a (8a). Workability when connecting 9) is improved. Further, in the base portion 6a (8a), since the region where the pair of connecting portions 6b (8b) are formed at both ends can be reduced, the positive electrode current collector 6 (negative electrode current collector) is formed by the pair of resistance welding electrodes during resistance welding. It is possible to prevent the base portion 6a (8a) from being deformed when the body 8) is sandwiched.

<Modification example 3>
FIG. 16 shows a current collector according to the third modification. In this way, narrow portions 6a2 (8a2) can be provided on both sides of the wide portion 6a1 (8a1). Further, connecting portions 6b (8b) can be provided at both ends of one narrow portion 6a2 (8a2), and connecting portions 6b (8b) can be provided at both ends of the other narrow portion 6a2 (8a2).

<Modification example 4>
FIG. 17 shows the current collector according to the modified example 4. The positive electrode terminal 7 (negative electrode terminal 9) may be connected to the base portion 6a (8a) in advance by welding or the like. When such a current collector is used, the positive electrode terminal 7 (negative electrode terminal 9) is inserted into the through hole of the sealing plate 2 from the inside of the battery, and the positive electrode terminal 7 (negative electrode) is placed on the external conductive member arranged on the outside of the battery. Fix the terminal 9) by caulking.

<Modification 5>
FIG. 18 shows a connection step between the positive electrode current collector 6 and the positive electrode tab portion 4c in the square secondary battery according to the modified example 5. As shown in FIG. 18, in the laminated positive electrode tab portions 4c, the current collector receiving component 41 can be arranged on the outer surface opposite to the side on which the connecting portion 6b of the positive electrode current collector 6 is arranged. The current collector receiving component 41 has a first region 41a arranged along the positive electrode tab portion 4c, and a bent portion 41b formed at the end portion of the first region 41a on the winding electrode body 3 side. If the bent portion 41b is formed, even if spatter occurs during resistance welding, the spatter scatters to the power generation portion (the portion where the positive electrode plate 4 and the negative electrode plate 5 are laminated) of the wound electrode body 3, and power is generated. It is possible to prevent the part from being damaged.

<Modification 6>
FIG. 19 shows a connection step between the positive electrode current collector 6 and the positive electrode tab portion 4c in the square secondary battery according to the modified example 6. In the positive electrode current collector 6, the spacer 42 can be arranged between the connection portion 6b on one side and the connection portion 6b on the other side. As a result, it is possible to prevent the positive electrode current collector 6 from being deformed when the laminated positive electrode tab portion 4c and the connection portion 6b of the positive electrode current collector 6 are sandwiched between the pair of resistance welded electrodes 40. The spacer 42 can be a metal member or a resin member. The spacer 42 is preferably an insulating resin member. Further, the spacer 42 can be plate-shaped, block-shaped, or columnar.

The contents described in the above-described embodiments and modifications can be applied to both the positive electrode side and the negative electrode side.

In the above-described embodiments and modifications, the positive electrode tab portion and the positive electrode current collector are connected and the negative electrode tab portion and the negative electrode current collector are connected by resistance welding, but other methods can also be used. be. For example, instead of resistance welding, ultrasonic welding, welding with a high energy ray such as a laser, or the like can be used.

<Modification 7>
The following configuration can be considered as the wound electrode body according to the modified example. FIG. 20 is a plan view of the positive electrode plate 54 (negative electrode plate 55). The positive electrode plate 54 (negative electrode plate 55) is formed with a positive electrode active material layer 54a (55a) on the positive electrode core body (negative electrode core body). Positive electrode core body exposed portions 54b (negative electrode core body exposed portions 55b) are formed at both ends in the longitudinal direction. A positive electrode tab 56 (negative electrode tab 57) is connected to each of the positive electrode core body exposed portion 54b (negative electrode core body exposed portion 55b) by welding or the like. The positive electrode tab 56 (negative electrode tab 57) is preferably a metal plate having a thickness thicker than that of the positive electrode core (negative electrode core).

Such a positive electrode plate 54 and a negative electrode plate 55 are wound via a separator, and a flat wound electrode body 60 in which a positive electrode tab 56 and a negative electrode tab 57 project from one end in a flat winding axial direction, respectively. (Fig. 21). Then, a square secondary battery can be manufactured by using a plurality of such flat wound electrode bodies 60. For example, a plurality of flat wound electrode bodies 60 are laminated and used in the orientation shown in FIG. In such a case, it is preferable to use four or more flat wound electrode bodies 60. By using four or more of such flat wound electrode bodies 60, it is possible to obtain a square secondary battery having a high volume energy density while suppressing a decrease in current collecting property.

The widths X2 and X3 of the positive electrode tab 56 and the negative electrode tab 57 are preferably 1/4 or more of the width X1 of the flat wound electrode body 60, respectively. As a result, the internal resistance can be reduced, and a square secondary battery having improved vibration resistance can be obtained. Further, in order to obtain a square secondary battery having further improved vibration resistance, as shown in FIG. 20, the positive electrode tab 56 (negative electrode tab 57) is one of the positive electrode tabs 54 (negative electrode plate 55) in the width direction. It is preferable that the terminals E1 are arranged beyond the center line C to the other end E2 side. As a result, the wound electrode body 60 is firmly connected to the sealing plate via each positive electrode tab 56 and each negative electrode tab 57.

<Current cutoff mechanism>
Either the conductive path between the positive electrode plate and the positive electrode terminal or the conductive path between the negative electrode plate and the negative electrode terminal operates as the internal pressure of the battery rises, and the conductive path between the positive electrode plate and the positive electrode terminal or the negative electrode plate A current cutoff mechanism that cuts off the conductive path between the negative electrode terminals and cuts off the current can be provided. In this case, the operating pressure of the gas discharge valve is preferably set to a value larger than the operating pressure of the current cutoff mechanism.

The current cutoff mechanism preferably includes a deformed plate that deforms as the internal pressure of the battery rises, and a broken portion that breaks as the deformed plate deforms. Then, it is preferable that this broken portion is formed in the positive electrode current collector. In this case, for example, the positive electrode current collector can be the positive electrode current collector 6 shown in FIG. In the positive electrode current collector 6, a thin-walled portion or a notch portion is formed as a break portion around the through hole 6c. A deformed plate is arranged above the base portion 6a of the positive electrode current collector 6. Then, the periphery of the through hole 6c is welded and connected to the lower surface of the deformed plate by laser welding or the like. As a result, when the deformed plate is deformed upward as the internal pressure of the battery rises, the thin-walled portion or notch portion provided in the base portion 6a is broken, and the conductive path is cut. In such a case, it is preferable that the positive electrode tab portion 4c and the positive electrode current collector 6 are connected by resistance welding. As a result, it is possible to suppress the adverse effect of vibration or the like on the broken portion as compared with the case where the positive electrode tab portion 4c and the positive electrode current collector 6 are ultrasonically welded. Further, as compared with the case where the positive electrode tab portion 4c and the positive electrode current collector 6 are laser-welded, it is possible to suppress that spatter or the like adversely affects the broken portion. Further, since the wide portion 6a1 (8a1) is formed, the fractured portion can be easily formed. Further, when an insulating member is arranged between the deformed plate and the base portion 6a and the insulating member and the base portion 6a are fixed, the wide portion 6a1 (8a1) can be easily fixed. As a method for this, for example, it is conceivable to provide a through hole or a notch in the wide portion 6a1 (8a1) and fit a protrusion formed on the insulating member into the through hole or the notch. Further, the portion where the connecting portion 6b is formed in the base portion is the narrow portion 6a2, and when the positive electrode tab portion 4c is connected to the connecting portion 6b, the deformation of the base portion 6a is suppressed, so that the broken portion is formed. It can prevent damage.

FIG. 22 shows a cross-sectional view of a square secondary battery provided with a current cutoff mechanism. In addition, this cross-sectional view corresponds to the enlarged view around the positive electrode terminal of FIG. A cup-shaped conductive member 60 having a tubular portion is arranged on the lower surface of the insulating member 10. The conductive member 60 has a through hole on the insulating member 10 side, and the positive electrode terminal 7 is inserted into the through hole and connected to the positive electrode terminal 7. The conductive member 60 opens to the inside of the battery. And the deforming plate 61 is arranged so as to close this opening. The peripheral edge of the deformable plate 61 is welded and connected to the conductive member 60, and the opening is sealed by the deformable plate 61. A positive electrode current collector 6 is connected to the inner surface of the deformed plate 61 on the battery side. The positive electrode current collector 6 has a through hole 63, and the edge portion of the through hole 63 is welded and connected to the deformed plate 61. A thin-walled portion 64 is formed around the welded and connected portion. Further, an annular groove portion 65 is formed in the thin-walled portion 64. When the pressure inside the battery rises, the central portion of the deformable plate 61 is deformed so as to float toward the sealing plate 2. Along with this, the connecting portion between the deformed plate 61 and the positive electrode current collector 6 is pulled toward the sealing plate 2, and the annular groove portion 65 is broken. As a result, the conductive path between the positive electrode plate and the positive electrode terminal 7 is cut, and the charging current is cut off. This can prevent further progress of overcharging.

A resin insulating plate 62 is arranged between the deformed plate 61 and the positive electrode current collector 6. The insulating plate 62 is latch-fixed to the insulating plate 10 (not shown). The insulating plate 62 has a fixing protrusion 67, and the protrusion 67 is inserted into a fixing through hole 66 formed in the positive electrode current collector 6, and the tip portion is enlarged in diameter. As a result, the insulating plate 62 and the base portion 6a of the positive electrode current collector 6 are connected and fixed.

FIG. 23 is a perspective view of the positive electrode current collector 6 used in the current cutoff mechanism. Note that FIG. 22 corresponds to a cross-sectional view taken along the line ZZ of FIG. 23. The positive electrode current collector 6 has a base portion 6a and a connecting portion 6b extending from the base portion 6a toward the electrode body. The base portion 6a includes a wide portion 6a1 having a large width in the thickness direction of the square secondary battery (short side direction of the sealing plate) and a narrow portion 6a2 having a width smaller than the wide portion 6a1 in the thickness direction of the square secondary battery. Have. Then, in the wide portion 6a1, the base portion 6a is connected to the deformable plate 61. Further, in the wide portion 6a1, the base portion 6a is fixed to the insulating plate 62. The connecting portion 6b is provided in the narrow portion 6a2.

With such a current cutoff mechanism, when the positive electrode tab portion 4c is welded and connected to the connection portion 6b of the positive electrode current collector 6, it is connected to a fragile portion (scheduled fracture portion) or a deformed plate 61 provided in the base portion 6a. It is possible to prevent an adverse effect on the connection portion of the base portion 6a. For example, it is possible to prevent spatter generated during welding of the connecting portion 6b and the positive electrode tab portion 4c from scattering to the fragile portion and the connecting portion. Alternatively, the stress at the time of welding the connecting portion 6b and the positive electrode tab portion 4c suppresses deformation of the fragile portion and the periphery of the connecting portion in the base portion 6a. The relationship between the width W1 of the wide portion 6a1 and the width W2 of the narrow portion 6a2 is preferably W1 / W2 ≧ 3/2 or more.

The current cutoff mechanism having such a configuration is also effective when the electrode body housed in the square outer body is one wound electrode body. Further, the current cutoff mechanism having such a configuration is effective even when the electrode body housed in the square outer body is a laminated electrode body.

The assembled battery using a plurality of square secondary batteries 20 can have the following configuration.

As shown in FIG. 24, in the assembled battery 50, a plurality of square secondary batteries 20 are stacked between the pair of end plates 51 so that their large area side walls are parallel to each other. The pair of end plates 51 are connected by a bind bar 52. The end plate and the bus bar are connected by using bolts, rivets, etc., or by welding. An insulating separator 53 is arranged between the square secondary batteries 20, and the separator 53 is preferably made of resin. Then, in the assembled battery 50, the positive electrode terminal 7 and the negative electrode terminal 9 of each square secondary battery 20 are arranged on one side surface (the front side surface in FIG. 24). The terminals of the adjacent square secondary batteries 20 are connected by a bus bar 54. The bottom of each square secondary battery 20 is arranged on the other side surface (the back side surface in FIG. 24). Then, the small area side walls of each square secondary battery 20 are arranged on the upper surface and the lower surface of the assembled battery 50. With such a configuration, the assembled battery has a low height and a very high volumetric energy density. Then, by mounting such an assembled battery 50 on the vehicle in the orientation shown in FIG. 24, the vehicle has a significantly improved habitability in the vehicle.

A cooling plate 55 through which a cooling medium flows is arranged on the bottom surface of the assembled battery 50, and it is preferable that each square secondary battery 20 is cooled by this cooling plate. The cooling medium may be a gas or a liquid.

1 ... Square exterior body 1a ... Bottom 1b ... Large area side wall 1c ... Small area side wall 2 ... Seal plate 3 ... Winding electrode body 4 ... Positive electrode plate 4a ... Positive electrode active material layer 4b ... Positive electrode core body exposed portion 4c ... Positive electrode tab portion 5 ... Negative electrode plate 5a ... Negative electrode active material layer 5b ... Negative electrode core body exposed portion 5c ... Negative electrode tab portion 6 ... Positive electrode current collector 6a ... Base 6b ... Connection 6c ... Through hole 7 ... Positive electrode terminal 7a ... Flange 7b ... Insertion 8 ... Negative electrode collection Electrical body 8a ・ ・ ・ Base part 8b ・ ・ ・ Connection part 8c ・ ・ ・ Through hole 9 ・ ・ ・ Negative electrode terminal 9a ・ ・ ・ Flange part 9b ・ ・ ・ Insert part 10, 12 ・ ・ ・ Insulating members 11, 13 ・・ ・ Gasket 14 ・ ・ ・ Insulation sheet 15 ・ ・ ・ Electrode liquid injection hole 16 ・ ・ ・ Sealing plug 17 ・ ・ ・ Gas discharge valve 20 ・ ・ ・ Square secondary battery 30 ・ ・ ・ Welded part 31 ・ ・ ・Straight part 32 ... Curved part 33 ... Stepped part 34 ... Protrusion 35 ... Slit 40 ... Resistance welding electrode 41 ... Current collector receiving component 42 ... Spacer 50 ... Assembled battery 51 ... End plate 52 ... Bind bar 53 ... Separator 54 ... Bus bar 55 ... Cooling plate 60 ... Conductive member 61 ... Deformation plate 62 ... Insulation plate 63 ...・ ・ Through hole 64 ・ ・ ・ Thin wall part 65 ・ ・ ・ Groove part 66 ・ ・ ・ Fixing through hole 67 ・ ・ ・ Fixing protrusion

Claims (16)

A flat wound electrode body in which a positive electrode plate and a negative electrode plate are wound via a separator, and
A square exterior body having an opening and accommodating the wound electrode body,
A sealing plate that seals the opening and
A positive electrode terminal electrically connected to the positive electrode plate and attached to the sealing plate,
A positive electrode current collector that electrically connects the positive electrode plate and the positive electrode terminal,
A negative electrode terminal electrically connected to the negative electrode plate and attached to the sealing plate,
A negative electrode current collector that electrically connects the negative electrode plate and the negative electrode terminal,
It is a square secondary battery equipped with
The wound electrode body has a positive electrode tab portion and a negative electrode tab portion at one end in a direction in which the winding shaft of the wound electrode body extends.
At least two of the wound electrode bodies are arranged so that their respective winding shafts are arranged in a direction perpendicular to the sealing plate, and the positive electrode tab portion and the negative electrode tab portion are located on the sealing plate side. Stored inside the square exterior
The positive electrode plate is independent for each wound electrode body.
The negative electrode plate is independent for each wound electrode body.
The joint portion between the positive electrode tab portion and the positive electrode current collector and the joint portion between the positive electrode current collector and the positive electrode terminal are displaced in the longitudinal direction of the sealing plate, and the sealing plate and the winding electrode are displaced. The body is out of alignment,
Square secondary battery. A flat wound electrode body in which a positive electrode plate and a negative electrode plate are wound via a separator, and
A square exterior body having an opening and accommodating the wound electrode body,
A sealing plate that seals the opening and
A positive electrode terminal electrically connected to the positive electrode plate and attached to the sealing plate,
A positive electrode current collector that electrically connects the positive electrode plate and the positive electrode terminal,
A negative electrode terminal electrically connected to the negative electrode plate and attached to the sealing plate,
A negative electrode current collector that electrically connects the negative electrode plate and the negative electrode terminal,
It is a square secondary battery equipped with
The wound electrode body has a positive electrode tab portion and a negative electrode tab portion at one end in a direction in which the winding shaft of the wound electrode body extends.
At least two of the wound electrode bodies are arranged so that their respective winding shafts are arranged in a direction perpendicular to the sealing plate, and the positive electrode tab portion and the negative electrode tab portion are located on the sealing plate side. Stored inside the square exterior
The positive electrode plate is independent for each wound electrode body.
The negative electrode plate is independent for each wound electrode body.
The joint portion between the negative electrode tab portion and the negative electrode current collector and the joint portion between the negative electrode current collector and the negative electrode terminal are displaced in the longitudinal direction of the sealing plate, and the sealing plate and the wound electrode are displaced. The body is out of alignment,
Square secondary battery. In a state where the plurality of the negative electrode tab portions are bundled, the negative electrode current collector and the negative electrode current collector receiving component are sandwiched and connected to the negative electrode current collector.
The square secondary battery according to claim 1 or 2. In a state where the plurality of positive electrode tabs are bundled, they are sandwiched between the positive electrode current collector and the positive electrode current collector receiving component and connected to the positive electrode current collector.
The square secondary battery according to any one of claims 1 to 3. The negative electrode current collector has a base portion and a connecting portion bent from an end portion of the base portion of the negative electrode current collector.
The negative electrode terminal is connected to the base portion of the negative electrode current collector, and the negative electrode terminal is connected to the base portion.
The negative electrode tab portion is connected to the connection portion of the negative electrode current collector.
The square secondary battery according to any one of claims 1 to 4. The positive electrode current collector has a base portion and a connecting portion bent from an end portion of the base portion of the positive electrode current collector.
The positive electrode terminal is connected to the base portion of the positive electrode current collector, and the positive electrode terminal is connected to the base portion.
The positive electrode tab portion is connected to the connection portion of the positive electrode current collector.
The square secondary battery according to any one of claims 1 to 5. The width of the negative electrode tab portion is 1/4 or more and 1/2 or less of the width of the wound electrode body.
The square secondary battery according to any one of claims 1 to 6. The width of the positive electrode tab portion is 1/4 or more and 1/2 or less of the width of the wound electrode body.
The square secondary battery according to any one of claims 1 to 7. The negative electrode plate has a negative electrode core body and a negative electrode active material layer formed on the negative electrode core body.
The negative electrode core has an exposed portion of the negative electrode core on which the negative electrode active material layer is not formed.
The negative electrode tab portion is the exposed negative electrode core body.
The square secondary battery according to any one of claims 1 to 7. The positive electrode plate has a positive electrode core and a positive electrode active material layer formed on the positive electrode core.
The positive electrode core has an exposed portion of the positive electrode core on which the positive electrode active material layer is not formed.
The positive electrode tab portion is the exposed positive electrode core body.
The square secondary battery according to any one of claims 1 to 9. The wound electrode body includes a first wound electrode body and a second wound electrode body.
A first negative electrode side welded portion in which a plurality of the negative electrode tab portions of the first wound electrode body are bundled and welded to the negative electrode current collector.
It has a second negative electrode side welded portion in which a plurality of the negative electrode tab portions of the second wound electrode body are bundled and welded to the negative electrode current collector.
In the negative electrode current collector, the first negative electrode side welded portion and the second negative electrode side welded portion are formed at distant positions.
The square secondary battery according to any one of claims 1 to 10. The wound electrode body includes a first wound electrode body and a second wound electrode body.
A first positive electrode side welded portion in which a plurality of the positive electrode tab portions of the first wound electrode body are bundled and welded to the positive electrode current collector.
It has a second positive electrode side welded portion in which a plurality of the positive electrode tab portions of the second wound electrode body are bundled and welded to the positive electrode current collector.
In the positive electrode current collector, the first positive electrode side welded portion and the second positive electrode side welded portion are formed at distant positions.
The square secondary battery according to any one of claims 1 to 11. The square exterior body has a bottom, a pair of large area side walls, and a pair of small area side walls.
The area of the small area side wall is smaller than the area of the large area side wall.
The area of the bottom is smaller than the area of the small side wall,
The square secondary battery according to any one of claims 1 to 12. The plurality of wound electrode bodies are arranged in an insulating sheet bent in a housing shape.
The insulating sheet includes a region having a surface extending in a direction in which the wound electrode bodies are arranged and facing the side wall of the square exterior body.
The square secondary battery according to any one of claims 1 to 13. An assembled battery including a plurality of square secondary batteries according to any one of claims 1 to 13.
With a pair of end plates
It has a bind bar that connects the pair of end plates, and
The plurality of square secondary batteries are assembled batteries arranged between the pair of end plates. An assembled battery including a plurality of square secondary batteries according to claim 15.
With a pair of end plates
It has a bind bar that connects the pair of end plates, and
The plurality of the square secondary batteries are arranged between the pair of end plates so that the large area side walls of the square secondary batteries are parallel to each other.
The positive electrode terminal and the negative electrode terminal of each of the square secondary batteries are arranged on one side surface.
An assembled battery in which the bottom of each of the square exterior bodies of each of the square secondary batteries is arranged on the other side surface.

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