JP2024057096A - Prismatic secondary battery and battery pack using the same - Google Patents

Abstract

[Problem] To provide a high-capacity prismatic secondary battery having a high volumetric 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 in the direction in which the winding axis extends, and the two flat wound electrode bodies 3 are arranged so that their respective winding axes are perpendicular to a sealing plate 2, and are housed in a prismatic exterior body 1 such that the positive electrode tab portion 4c and the negative electrode tab portion 5c are located on the sealing plate 2 side. [Selected Figure] Figure 3

Description

The present invention relates to a prismatic secondary battery and a battery pack using the same.

Secondary batteries such as alkaline secondary batteries and non-aqueous electrolyte secondary batteries are used as driving power sources for electric vehicles (EVs) and hybrid electric vehicles (HEVs, PHEVs). These applications require high capacity and high output characteristics, so multiple rectangular secondary batteries are used in series or parallel connected battery packs.

In these prismatic secondary batteries, a battery case is formed by a cylindrical prismatic exterior body with a bottom and an opening, and a sealing plate that seals the opening. An electrode body consisting of a positive electrode plate, a negative electrode plate, and a separator is stored in the battery case together with an electrolyte. 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 metallic positive electrode core and a positive electrode active material layer formed on the surface of the positive electrode core. A positive electrode core exposed portion where the positive electrode active material layer is not formed is formed in a part of the positive electrode core. The positive electrode current collector is connected to this positive electrode core exposed portion. The negative electrode plate includes a metallic negative electrode core and a negative electrode active material layer formed on the surface of the negative electrode core. A negative electrode core exposed portion where the negative electrode active material layer is not formed is formed in a part of the negative electrode core. The negative electrode current collector is connected to this negative electrode core exposed portion.

For example, Patent Document 1 proposes a prismatic secondary battery using a wound electrode body having a wound positive electrode core exposed portion at one end and a wound negative electrode core exposed portion at the other end. Patent Document 2 proposes a prismatic secondary battery using a wound electrode body having a positive electrode core exposed portion and a negative electrode core exposed portion at one end.

JP 2009-032640 A JP 2008-226625 A

There is a demand for the development of secondary batteries with higher volumetric energy density and larger battery capacity for in-vehicle secondary batteries, particularly those used in EVs, PHEVs, etc. In the case of the prismatic secondary battery disclosed in the above Patent Document 1, the battery case requires left and right spaces for arranging the wound positive electrode core exposed portion and the wound negative electrode core exposed portion, as well as an upper space between the sealing plate and the wound electrode body, which makes it difficult to increase the volumetric energy density of the secondary battery.

In contrast, by using a wound electrode body having a positive electrode core exposed portion and a negative electrode core exposed portion at one end, as in the case of the prismatic secondary battery disclosed in Patent Document 2, it becomes easier to obtain a prismatic secondary battery with a high volumetric energy density.

However, the prismatic secondary battery disclosed in Patent Document 2 tends to have a more complex current collecting section structure than the prismatic secondary battery disclosed in Patent Document 1.

The present invention aims to provide a high-capacity rectangular secondary battery with high volumetric energy density and a battery pack using the same.

A prismatic secondary battery according to one embodiment of the present invention is a prismatic secondary battery comprising: a flat wound electrode body in which a positive electrode plate and a negative electrode plate are wound with a separator interposed therebetween; a prismatic exterior body having an opening and housing the wound electrode body; a sealing plate that seals the opening; a positive electrode terminal electrically connected to the positive electrode plate and attached to the sealing plate; a positive electrode 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; and a negative electrode collector that electrically connects the negative electrode plate and the negative electrode terminal, wherein the wound electrode body is arranged in such a manner that the wound electrode body is wound in a direction in which the winding axis of the wound electrode body extends. At least two of the wound electrode bodies are housed in the rectangular exterior body so that the winding axis of each is arranged perpendicular to the sealing plate, the positive electrode tab portion and the negative electrode tab portion are located on the sealing plate side, the positive electrode plate is independent for each wound electrode body, the negative electrode plate is independent for each wound electrode body, the joint between the positive electrode tab portion and the positive electrode collector and the joint between the positive electrode collector and the positive electrode terminal are offset in the longitudinal direction of the sealing plate, and the sealing plate and the wound electrode body are offset in the direction facing each other. Alternatively, the joint between the negative electrode tab portion and the negative electrode collector and the joint between the negative electrode collector and the negative electrode terminal are offset in the longitudinal direction of the sealing plate, and the sealing plate and the wound electrode body are offset in the direction facing each other.

With this configuration, a flat wound electrode body is used in which a positive electrode tab portion and a negative electrode tab portion are formed on one end side in the direction in which the winding axis extends, and the positive electrode tab portion and the negative electrode tab portion are arranged on the sealing plate side, thereby reducing the space inside the battery case that is not involved in power generation. This results in a prismatic secondary battery with a higher volumetric energy density and larger battery capacity.

Furthermore, by having multiple flat wound electrode bodies housed in a rectangular exterior body, it is possible to simplify the configuration of the connection between the positive electrode tab portion and the positive electrode current collector and the connection between the negative electrode tab portion and the negative electrode current collector.

The positive electrode collector and the positive electrode terminal may be integrated into one component. The negative electrode collector and the negative electrode terminal may be integrated into one component. The positive electrode collector and the positive electrode terminal may be electrically connected via another conductive member. The negative electrode collector and the positive electrode terminal may be electrically connected via another conductive member.

The rectangular 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 sidewall is smaller than the area of the large area sidewall;
The area of the bottom is preferably smaller than the area of the small area sidewall.

With this configuration, of the six outer surfaces of the battery case formed by the rectangular exterior body and the sealing plate, the surface area of the bottom and the sealing plate is smaller than the other four surfaces. This makes it possible to reduce the space formed between the wound electrode body and the sealing plate in which the positive electrode tab portion, negative electrode tab portion, positive electrode current body, negative electrode current collector, etc. are arranged. This results in a rectangular secondary battery with a higher volumetric energy density.

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 a positive electrode core exposed portion on which the positive electrode active material layer is not formed, the negative electrode plate has a negative electrode core and a negative electrode active material layer formed on the negative electrode core, the negative electrode core has a negative electrode core exposed portion on which the negative electrode active material layer is not formed, and 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. The negative tab portion is preferably composed of a negative core. The positive electrode tab portion and the negative electrode tab portion can be separate parts from the core connected to the positive electrode core or the negative electrode core. For example, a metal plate made of aluminum, an aluminum alloy, copper, a copper alloy, nickel, a 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 tab portions, each having approximately the same width, are formed at approximately 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 when the positive electrode plate is unfolded. The spacing between the positive electrode tab portions means the distance between the positive electrode tab portions along the longitudinal direction of the positive electrode plate when the positive electrode plate is unfolded. The approximately same width means that the width of each positive electrode tab portion is within a range of plus or minus 10%. It is preferable that the width of each positive electrode tab portion is within a range of plus or minus 5%. The approximately equal spacing means that the spacing between each positive electrode tab portion is within a range of plus or minus 10%. It is preferable that the spacing between each positive electrode tab portion is within a range of plus or minus 5% of the width of each positive electrode tab portion.

This configuration makes the charge/discharge reaction within the positive plate more uniform. In addition, the positive plate can be easily manufactured.

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

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

The positive electrode tab portions are stacked in a shifted state, thereby forming a positive electrode step portion formed by ends of the positive electrode tab portions,
It is preferable that a positive electrode current collector is connected to the positive electrode step portion.

It is preferable that the negative electrode tab portions, each having approximately the same width, are formed at approximately 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 when the negative electrode plate is unfolded. The spacing between the negative electrode tab portions means the distance between the negative electrode tab portions along the longitudinal direction of the negative electrode plate when the negative electrode plate is unfolded. The term "approximately the same width" means that the width of each negative electrode tab portion is within a range of plus or minus 10%. It is preferable that the width of each negative electrode tab portion is within a range of plus or minus 5%. The term "approximately equal spacing" means that the spacing between each negative electrode tab portion is within a range of plus or minus 10%. It is preferable that the spacing between each negative electrode tab portion is within a range of plus or minus 5% of the width of each negative electrode tab portion.

This configuration makes the charge/discharge reaction within the negative plate more uniform. In addition, the negative plate can be easily manufactured.

It is preferable that the width of the negative electrode tab portion is greater than or equal to 1/4 and less than or equal to 1/2 the width of the wound electrode body.

The negative electrode tab portions are stacked in a shifted state, thereby forming a negative electrode step portion formed by ends of the negative electrode tab portions,
It is preferable that a negative electrode current collector is connected to the negative electrode step portion.

A battery pack according to one embodiment of the present invention includes:
A plurality of the prismatic secondary batteries;
A pair of end plates;
a bind bar connecting the pair of end plates,
the plurality of rectangular secondary batteries are stacked between the pair of end plates with their large-area side walls oriented parallel to each other;
The positive electrode terminal and the negative electrode terminal of each of the rectangular secondary batteries are disposed on one side surface,
The bottom surface of each of the rectangular exterior bodies of each of the rectangular secondary batteries is disposed on the other side surface.

The present invention provides a high-capacity rectangular secondary battery with high volumetric energy density and a battery pack using the same.

1 is a perspective view of a prismatic secondary battery according to an embodiment; 2 is a cross-sectional view taken along line II-II in FIG. 1. 2 is a cross-sectional view taken along line III-III in FIG. 1. FIG. 2 is a cross-sectional view taken along line IV-IV in FIG. 2 is a cross-sectional view taken along line VV in FIG. 1. FIG. 2 is a plan view of a positive electrode plate according to the embodiment. FIG. 2 is a plan view of a negative electrode plate according to the embodiment. 1 is a view of a wound electrode body according to an embodiment as viewed along a direction in which a winding axis extends. FIG. FIG. 1A to 1C are diagrams showing a process of connecting the tab portion and the current collector. FIG. 4 is a diagram showing a connection portion between a tab portion and a current collector. FIG. 11 is a diagram of a wound electrode body used in a prismatic secondary battery according to a reference example. FIG. 2 is a diagram of a wound electrode body used in the prismatic secondary battery according to the embodiment. FIG. 13 is a perspective view of a current collector according to a modified example. FIG. 13 is a perspective view of a current collector according to a modified example. FIG. 13 is a perspective view of a current collector according to a modified example. FIG. 13 is a perspective view of a current collector according to a modified example. 10A to 10C are diagrams illustrating a process of connecting the tab portion and the current collector in a modified prismatic secondary battery. 10A to 10C are diagrams illustrating a process of connecting the tab portion and the current collector in a modified prismatic secondary battery. 13 is a plan view of a positive electrode plate and a negative electrode plate according to a modified example. FIG. 13A and 13B are diagrams showing a wound electrode body according to a modified example. 13 is a cross-sectional view of a current interruption mechanism of a prismatic secondary battery according to a modified example. FIG. 2 is a perspective view of a current collector used in the current interruption device. 1 is a perspective view of a battery pack according to an embodiment;

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

As shown in Figures 2 to 4, two flat wound electrode bodies 3 are arranged in the rectangular exterior body 1 so that the direction in which their winding axes extend is perpendicular to the sealing plate 2. The positive electrode core exposed portion 4b and the negative electrode core exposed portion 5b of each wound electrode body 3 are located on the sealing plate 2 side. The positive electrode core exposed portions 4b of each wound electrode body 3 are located on the same side (upper side in Figure 2), and the negative electrode core exposed portions 5b of each wound electrode body 3 are located on the same side (lower side in Figure 2).

At one end of the wound electrode body 3 in the direction in which the winding axis extends, a stacked positive electrode core exposed portion 4b and a stacked negative electrode core exposed portion 5b are provided. A positive electrode current collector 6 is welded to the stacked positive electrode core exposed portion 4b to form a welded portion 30. A positive electrode terminal 7 is electrically connected to this positive electrode current collector 6. A negative electrode current collector 8 is welded to the stacked negative electrode core exposed portion 5b to form a welded portion 30. A negative electrode terminal 9 is electrically connected to this 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 an insulating member 10 and a gasket 11, respectively. The negative electrode terminal 9 and the negative electrode current collector 8 are fixed to the sealing plate 2 via an insulating member 12 and a gasket 13, respectively. The gaskets 11 and 13 are disposed between the sealing plate 2 and each of the terminals 7 and 9, respectively. The insulating members 10 and 12 are disposed between the sealing plate 2 and each of the current collectors 6 and 8, respectively. The gaskets and the insulating members are preferably made of insulating resin materials. The wound electrode body 3 is accommodated in the rectangular exterior body 1 in a state where it is covered with an insulating sheet 14 folded into a box shape. The insulating sheet 14 covers the wound electrode body 3 and is disposed between the wound electrode body 3 and the rectangular exterior body 1. The sealing plate 2 is welded to the opening edge of the rectangular exterior body 1 by laser welding or the like. The sealing plate 2 has an electrolyte injection hole 15, and this electrolyte injection hole 15 is sealed by a sealing plug 16 after electrolyte injection. The sealing plate 2 is formed with a gas exhaust valve 17 for exhausting gas when the pressure inside the battery becomes high.

The size of the prismatic secondary battery 20 can be, for example, 18 cm in width (length perpendicular to the sealing plate 2; length in the left-right direction in FIG. 1), 3 cm in thickness (length in the front-to-back direction in FIG. 1), and 9 cm in height (length parallel to the sealing plate 2 and perpendicular to the thickness direction of the prismatic secondary battery 20; length in the up-to-down direction in FIG. 1).

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

The manufacturing method for the following rectangular secondary battery 20 will be described.

[Preparation 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. Thereafter, a compression process is performed so that the positive electrode active material layer has a predetermined thickness. The positive electrode plate obtained in this way is cut so that a positive electrode core exposed portion of a predetermined width is formed at one end in the width direction at a predetermined interval.

As shown in FIG. 6, the positive electrode plate 4 obtained in this manner has a positive electrode active material layer 4a formed on the positive electrode core. Positive electrode core exposed portions 4b of a predetermined width are formed at one end in the width direction at a predetermined interval. The positive electrode core exposed portions 4b constitute the positive electrode tab portions 4c.

The width W1 of each positive electrode tab portion 4c is 40 mm. The spacing W2 between each positive electrode tab portion 4c is 120 mm. Note that the width W1 of the positive electrode tab portion 4c is the width in the longitudinal direction of the positive electrode plate.

[Preparation 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 it, the water in the negative electrode slurry is removed, and a negative electrode active material layer is formed on the negative electrode core. Then, a compression process is performed so that the negative electrode active material layer has a predetermined thickness. The negative electrode plate obtained in this way is cut so that a negative electrode core exposed portion of a predetermined width is formed at one end in the width direction at a predetermined interval.

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

The width W3 of each negative electrode tab portion 5c is 40 mm. The spacing W4 between each negative electrode tab portion 5c is 120 mm. The width W3 of the negative electrode tab portion is the width in the longitudinal direction of the negative electrode plate 5.

The relationship between the width W1 of the positive electrode tab portion 4c, the spacing 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 preferably W1+W2>2L. In addition, it is preferable that W1+2πR<L and that when the winding start position of the positive electrode plate is 0°, the winding start position of the negative electrode plate is 180-270°.

In addition, the relationship between the width W2 of the negative electrode tab portion 5c, the spacing 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 preferably W3+W4>2L.

[Wound electrode body]
The positive electrode plate 4 and the negative electrode plate 5 obtained by the above-mentioned method are shifted so that the positive electrode tab portion 4c and the negative electrode tab portion 5c do not overlap, and a polyethylene porous separator is interposed between them, and then the plates are stacked, wound, and pressed to form a flat wound electrode body 3.

Figure 8 is a diagram showing the surface of the wound electrode body 3 on which the positive electrode tab 4c and negative electrode tab 5c are formed. As shown in Figure 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 axis extends. Then, the positive electrode tab 4c is stacked 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 perpendicular to the thickness direction of the wound electrode body 3), and the negative electrode tab portion 5c is stacked on the other side.

The positive electrode tab portion 4c and the negative electrode tab portion 5c each have a straight portion 31 arranged on the straight portion (flat end) of the wound electrode body 3, and a curved portion 32 arranged on the curved portion (curved portion) of the wound electrode body 3. In addition, each positive electrode tab portion 4c is arranged and stacked so as to be shifted slightly from the start of winding to the end of winding. In addition, each negative electrode tab portion 5c is arranged and stacked so as to be shifted slightly from the start of winding to the end of winding. Therefore, the stacked positive electrode tab portion 4c has a step portion 33 formed by the end of each positive electrode tab portion 4c. In addition, the stacked negative electrode tab portion 5c has a step portion 33 formed by the end of each negative electrode tab portion 5c.

Two wound electrode bodies 3 thus produced are prepared, and the positive electrode tab portion 4c and the negative electrode tab portion 5c are arranged on the same side, and the two wound electrode bodies 3 are fixed together with insulating tape. At least two wound electrode bodies 3 are required, and the number is not particularly limited. Although it is not necessary to fix multiple wound electrode bodies 3, it is preferable to fix them together. The fixing method is not particularly limited, and they may be fixed with insulating tape, or they may be fixed together by placing them in an insulating sheet formed into a bag or box shape.

[Assembly of sealing plate, current collector and terminal]
As shown in FIG. 1 and FIG. 2, at one end of the sealing plate 2 in the longitudinal direction, a gasket 11 is disposed on the outer side of the sealing plate 2 on the battery side, and an insulating member 10 is disposed on the inner side of the sealing plate 2 on the battery side. The positive electrode terminal 7 has a flange portion 7a and an insertion portion 7b. The positive electrode terminal 7 is disposed on the gasket 11, and the positive electrode current collector 6 is disposed 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, and the positive electrode terminal 7 is inserted into these through holes from the outer side of the battery, and the tip of the positive electrode terminal 7 is crimped, so that the positive electrode terminal 7, the gasket 11, the sealing plate 2, the insulating member 10, and the positive electrode current collector 6 are fixed integrally. It is preferable to weld the crimped portion of the positive electrode terminal 7 to the positive electrode current collector 6 by laser welding or the like.

At the other end of the sealing plate 2 in the longitudinal direction, a gasket 13 is disposed on the outer side of the sealing plate 2, and an insulating member 12 is disposed on the inner side of the sealing plate 2. The negative terminal 9 has a flange portion 9a and an insertion portion 9b. The negative terminal 9 is disposed on the gasket 13, and the negative current collector 8 is disposed 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 current collector 8, and the negative terminal 9 is inserted into these through holes from the outer side of the battery, and the tip of the negative terminal 9 is crimped, thereby fixing the negative terminal 9, the gasket 13, the sealing plate 2, the insulating member 12, and the negative current collector 8 together. It is preferable to weld the crimped portion of the negative terminal 9 to the negative current collector 8 by laser welding or the like.

The positive electrode collector 6 and the negative electrode collector 8 shown in FIG. 9 are used. The positive electrode collector 6 will be described as an example. The positive electrode collector 6 has a base portion 6a to which the positive electrode terminal 7 is connected, and a connection portion 6b extending from the end 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 this through hole 6c, and the tip of the positive electrode terminal 7 is crimped onto the base portion 6a, thereby connecting the positive electrode terminal 7 and the positive electrode collector 6. The connection portion 6b is provided at both ends of the base portion 6a in the thickness direction of the battery (the front end and the back end in FIG. 9). A protrusion 34 is formed in the connection portion 6b. In addition, a slit 35 is formed in the connection portion 6b. The negative electrode collector 8 can also be formed in the same shape as the positive electrode collector 6. It is preferable to form the positive electrode collector 6 and the negative electrode collector 8 by bending a plate-shaped metal member.

[Connection between current collector and wound electrode body]
10 is a cross-sectional view showing a process of connecting the tab portion and the current collector, corresponding to FIG. 2 and FIG. 3. As shown in FIG. 10, the stacked positive electrode tab portion 4c is arranged on the protrusion 34 formed on the connection portion 6b of the positive electrode current collector 6 on one side and the other side. Then, a resistance welding current is applied to the stacked positive electrode tab portion 4c and the positive electrode current collector 6 while the stacked positive electrode tab portion 4c and the positive electrode current collector 6 are sandwiched between a pair of resistance welding electrodes 40, and resistance welding is performed. As a result, the stacked 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 a similar manner.

When using the positive electrode collector 6 or the negative electrode collector 8 shown in FIG. 9, first, the part where the protrusions 34 are formed on the front and back sides of the left side of FIG. 9 is welded by the method shown in FIG. 10. Then, the part where the protrusions 34 are formed on the front and back sides of the right side of FIG. 9 is welded by the method shown in FIG. 10. At this time, as shown in FIG. 9, since the slit 35 is formed in the connection part 6b, it is possible to suppress the generation of reactive current (current not involved in resistance welding) passing through the first welded part that has already been resistance welded when resistance welding at the second place. The order of resistance welding may be either the left side or the right side in FIG. 9 first, or they may be performed simultaneously. The same method can be used for the negative electrode side.

11, the positive electrode current collector 6 can be welded to the step portion 33 of the positive electrode tab portion 4c. This allows 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 periphery side of the wound electrode body 3 to be more firmly connected to the positive electrode current collector 6.
The positive electrode tab portion 4c located on the inner periphery side of the positive electrode current collector 6 is welded at a position close to the positive electrode current collector 6. This allows for more uniform current collection. A similar method can be used for the negative electrode side.

Next, the wound electrode body 3 connected to the positive electrode collector 6 and the negative electrode collector 8 is inserted into the rectangular exterior body 1 while being placed inside the insulating sheet 14 folded into a box shape. The insulating sheet 14 includes an area having a surface that extends in the direction in which the wound electrode bodies 3 are arranged and faces the side wall of the rectangular exterior body 1. The joint between the sealing plate 2 and the rectangular exterior body 1 is then welded by laser welding to seal the opening of the rectangular exterior body 1. Thereafter, nonaqueous electrolyte is injected through the electrolyte injection hole 15 provided in the sealing plate 2, and the electrolyte injection hole 15 is sealed with a sealing plug 16 to produce a rectangular secondary battery 20.

In the rectangular secondary battery 20, the positive electrode tab portion 4c and the negative electrode tab portion 5c are arranged on the sealing plate 2 side of the wound electrode body 3. Therefore, the space in the rectangular exterior body 1 where components not involved in power generation are arranged can be reduced, resulting in a rectangular secondary battery with a high volumetric energy density. Furthermore, in the rectangular secondary battery 20, the sealing plate 2 is arranged on the surface with the smallest area among the six surfaces of the battery case formed by the rectangular exterior body 1 and the sealing plate 2. That is, the area of the sealing plate 2 and the bottom 1a of the rectangular exterior body 1 is smaller than the four side walls (a pair of large-area side walls 1b and a pair of small-area side walls 1c) of the rectangular exterior body 1. This allows the space where components not involved in power generation are arranged to be minimized, resulting in a battery with a higher volumetric energy density.

Furthermore, in the rectangular secondary battery 20, the electrode body housed in the rectangular exterior body 1 is made up of multiple flat wound electrode bodies 3.

When manufacturing a large-capacity (for example, battery capacity of 30 Ah or more) rectangular secondary battery, if the electrode body housed in the rectangular exterior body 1 is a single wound electrode body, the wound electrode body becomes a wound electrode body with a large number of windings and a large thickness as shown in FIG. 12. In such a wound electrode body, it is difficult to align each positive electrode tab portion 4c with each other and each negative electrode tab portion 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. In addition, there is a risk that the positive electrode tab portion 4c and the negative electrode tab portion 5c will easily come into contact with each other. In addition, it becomes difficult to connect the positive electrode tab portion 4c to the positive electrode collector 6 and the negative electrode tab portion 5c to the negative electrode collector 8.

In contrast, by forming the electrode body housed in the rectangular exterior body 1 into a plurality of flat wound electrode bodies 3, it becomes easier to align the positive electrode tab portions 4c with each other and the negative electrode tab portions 5c with each other. In addition, even if the width of each positive electrode tab portion 4c and each negative electrode tab portion 5c is increased, the contact between the positive electrode tab portion 4c and the negative electrode tab portion 5c can be easily prevented (see FIG. 13). Therefore, as in the rectangular secondary battery 20, by dividing the electrode body housed in the rectangular exterior body 1 into a plurality of pieces, the contact between the positive electrode tab portion 4c and the negative electrode tab portion 5c is prevented, while the width of the positive electrode tab portion 4c and the negative electrode tab portion 5c is increased, improving the current collection efficiency, and further preventing the positive electrode tab portion 4c or the negative electrode tab portion 5c from being damaged or broken due to vibration or the like. Therefore, a rectangular secondary battery with excellent current collection efficiency and high reliability can be obtained.

<Modification 1>
14 shows a current collector according to Modification 1. In the positive current collector 6 (negative current collector 8), the protrusion 34 provided on the connection portion 6b (8b) can be a linear protrusion extending laterally. With this configuration, it is possible to allow the resistance welding electrode 40 to be misaligned with respect to the protrusion 34 during welding. This results in a current collecting structure with better productivity and welding quality.

<Modification 2>
FIG. 15 shows a collector according to the second modification. In the positive electrode collector 6 (negative electrode collector 8), the welded portion may be formed at one location each on the front side and the back side. The protrusion 34 may be dot-shaped (square, circular, hemispherical, etc.). The base portion 6a (8a) has a wide portion 6a1 (8a1) having a large width in the thickness direction of the rectangular secondary battery 20 and a narrow portion 6a2 (8a2) having a width smaller than that of the wide portion 6a1 (8a1) in the thickness direction of the rectangular secondary battery 20. The positive electrode terminal 7 (negative electrode terminal 9) is connected to the wide portion 6a1 (8a1). The connection portion 6b (8b) is formed at the end of the narrow portion 6a2 (8a2). With this configuration, the area of the base portion 6a (8a) to which the positive electrode terminal 7 (negative electrode terminal 9) is connected can be made wider, improving the workability when connecting the positive electrode terminal 7 (negative electrode terminal 9) to the base portion 6a (8a). Also, the area of the base portion 6a (8a) where the pair of connection portions 6b (8b) are formed at both ends can be made smaller, so that deformation of the base portion 6a (8a) can be suppressed when the positive electrode collector 6 (negative electrode collector 8) is sandwiched between a pair of resistance welding electrodes during resistance welding.

<Modification 3>
16 shows a current collector according to Modification 3. In this manner, narrow portions 6a2 (8a2) can be provided on both sides of wide portion 6a1 (8a1). Also, connection portions 6b (8b) can be provided on both ends of one narrow portion 6a2 (8a2), and connection portions 6b (8b) can be provided on both ends of the other narrow portion 6a2 (8a2).

<Modification 4>
17 shows a current collector according to Modification 4. The positive electrode terminal 7 (negative electrode terminal 9) may be previously connected to the base portion 6a (8a) 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 terminal 9) is fixed by crimping onto an external conductive member arranged on the outside of the battery.

<Modification 5>
18 shows a process for connecting the positive electrode collector 6 and the positive electrode tab portion 4c in the prismatic secondary battery according to the fifth modification. As shown in FIG. 18, the current collector receiving part 41 can be arranged on the outer surface of the stacked positive electrode tab portion 4c opposite to the side on which the connection portion 6b of the positive electrode collector 6 is arranged. The current collector receiving part 41 has a first region 41a arranged along the positive electrode tab portion 4c and a bent portion 41b formed at the end of the first region 41a on the side of the wound electrode body 3. If the bent portion 41b is formed, even if spatter occurs during resistance welding, it is possible to prevent the spatter from scattering toward the power generation portion (the portion where the positive electrode plate 4 and the negative electrode plate 5 are stacked) of the wound electrode body 3 and damaging the power generation portion.

<Modification 6>
FIG. 19 shows a process of connecting the positive electrode collector 6 and the positive electrode tab portion 4c in the prismatic secondary battery according to the sixth modification. A spacer 42 can be disposed between the connection portion 6b on one side of the positive electrode collector 6 and the connection portion 6b on the other side of the positive electrode collector 6. This can prevent the positive electrode collector 6 from being deformed when the stacked positive electrode tab portion 4c and the connection portion 6b of the positive electrode collector 6 are sandwiched between a pair of resistance welding electrodes 40. The spacer 42 can be a metal member or a resin member. The spacer 42 is preferably an insulating resin member. The spacer 42 can be a plate-like, block-like, or column-like.

The contents described in the above embodiments and variations can be applied to both the positive and negative electrode sides.

In the above-described embodiment and modified examples, the positive electrode tab portion and the negative electrode current collector are connected by resistance welding, but other methods may also be used.
For example, instead of resistance welding, ultrasonic welding or welding using high energy rays such as laser can be used.

<Modification 7>
The following configurations are conceivable as the wound electrode body according to the modified example. FIG. 20 is a plan view of a positive electrode plate 54 (negative electrode plate 55). The positive electrode plate 54 (negative electrode plate 55) has a positive electrode active material layer 54a (55a) formed on a positive electrode core (negative electrode core). A positive electrode core exposed portion 54b (negative electrode core exposed portion 55b) is 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 exposed portions 54b (negative electrode core 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 greater than that of the positive electrode core (negative electrode core).

The positive electrode plate 54 and the negative electrode plate 55 are wound with a separator interposed therebetween to form a flat wound electrode body 60 in which a positive electrode tab 56 and a negative electrode tab 57 protrude from one end of the flat winding axis direction (FIG. 21). A prismatic secondary battery can be produced by using a plurality of such flat wound electrode bodies 60. For example, a plurality of flat wound electrode bodies 60 are stacked in the orientation shown in FIG. 21 for use. In this case, it is preferable to use four or more flat wound electrode bodies 60. By using four or more such flat wound electrode bodies 60, a prismatic secondary battery with high volumetric energy density can be produced while suppressing a decrease in current collection performance.

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. This reduces the internal resistance and improves the vibration resistance of the rectangular secondary battery. In order to improve the vibration resistance of the rectangular secondary battery, it is preferable that the positive electrode tab 56 (negative electrode tab 57) is arranged in the width direction of the positive electrode plate 54 (negative electrode plate 55) from one end E1 to the other end E2 beyond the center line C, as shown in FIG. 20. This allows the wound electrode body 60 to be firmly connected to the sealing plate via each positive electrode tab 56 and each negative electrode tab 57.

<Current interruption mechanism>
A current interruption mechanism may be provided in either the conductive path between the positive plate and the positive terminal or the conductive path between the negative plate and the negative terminal, which is activated in response to an increase in the battery internal pressure and cuts off the conductive path between the positive plate and the positive terminal or the conductive path between the negative plate and the negative terminal to interrupt the current. In this case, the operating pressure of the gas release valve is preferably set to a value higher than the operating pressure of the current interruption mechanism.

The current interrupt mechanism is preferably configured to include a deformation plate that deforms with an increase in the battery internal pressure and a fracture portion that breaks with the deformation of the deformation plate. The fracture portion is preferably formed on the positive electrode collector. In this case, for example, the positive electrode collector can be the positive electrode collector 6 shown in FIG. 15. In the positive electrode collector 6, a thin portion or a notch portion is formed around the through hole 6c as a fracture portion. The deformation plate is disposed above the base portion 6a of the positive electrode collector 6. Then, the periphery of the through hole 6c is welded and connected to the lower surface of the deformation plate by laser welding or the like. As a result, when the deformation plate deforms upward with an increase in the battery internal pressure, the thin portion or the notch portion provided on the base portion 6a breaks, and the conductive path is cut off. In such a case, the connection between the positive electrode tab portion 4c and the positive electrode collector 6 is preferably performed by resistance welding. As a result, compared to the case where the positive electrode tab portion 4c and the positive electrode collector 6 are ultrasonically welded, it is possible to suppress the adverse effect of vibrations on the fracture portion. In addition, compared to the case where the positive electrode tab portion 4c and the positive electrode current collector 6 are laser-welded, it is possible to suppress the adverse effect of spatters and the like on the fractured portion. In addition, since the wide portion 6a1 (8a1) is formed, the fractured portion can be easily formed. In addition, when an insulating member is disposed between the deformation plate and the base portion 6a and this insulating member and the base portion 6a are fixed, the fixing can be easily performed at the wide portion 6a1 (8a1). As a method for this, for example, a through hole or a notch portion can be provided in the wide portion 6a1 (8a1) and a protrusion formed on the insulating member can be fitted into the through hole or the notch portion. In addition, the portion where the connection 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 connection portion 6b, the deformation of the base portion 6a is suppressed, so that the fractured portion can be suppressed from being damaged.

Figure 22 shows a cross-sectional view of a prismatic secondary battery equipped with a current interruption mechanism. This cross-sectional view corresponds to the enlarged view of the positive terminal periphery in Figure 2. A cup-shaped conductive member 60 having a cylindrical portion is disposed 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 terminal 7 is inserted into this through hole and connected to the positive terminal 7. The conductive member 60 opens to the inside of the battery. A deformation plate 61 is disposed to close this opening. The periphery of the deformation plate 61 is welded to the conductive member 60, and the opening is sealed by the deformation plate 61. A positive electrode current collector 6 is connected to the surface of the deformation plate 61 on the inside of the battery. The positive electrode current collector 6 has a through hole 63, and the edge of this through hole 63 is welded to the deformation plate 61. A thin-walled portion 64 is formed around the welded portion. In addition, a ring-shaped groove portion 65 is formed in the thin-walled portion 64. When the pressure inside the battery rises, the center of the deformable plate 61 deforms so that it rises toward the sealing plate 2. As a result, the connection between the deformable plate 61 and the positive electrode current collector 6 is pulled toward the sealing plate 2, and the annular groove 65 breaks. This cuts off the conductive path between the positive electrode plate and the positive electrode terminal 7, and the charging current is interrupted. This makes it possible to prevent further overcharging.

A resin insulating plate 62 is disposed between the deformation plate 61 and the positive electrode collector 6. The insulating plate 62 is latched to the insulating plate 10 (not shown). The insulating plate 62 has a fixing protrusion 67, which is inserted into a fixing through hole 66 formed in the positive electrode collector 6, and the tip portion is expanded in diameter. This connects and fixes the insulating plate 62 to the base portion 6a of the positive electrode collector 6.

Figure 23 is a perspective view of a positive electrode collector 6 used in a current interruption mechanism. Note that Figure 22 corresponds to a cross-sectional view taken along line Z-Z in Figure 23. The positive electrode collector 6 has a base portion 6a and a connection portion 6b extending from the base portion 6a toward the electrode body. The base portion 6a has a wide portion 6a1 that is wide in the thickness direction of the rectangular secondary battery (the short side direction of the sealing plate) and a narrow portion 6a2 that is narrower than the wide portion 6a1 in the thickness direction of the rectangular secondary battery. In the wide portion 6a1, the base portion 6a is connected to the deformation plate 61. In the wide portion 6a1, the base portion 6a is fixed to the insulating plate 62. The connection portion 6b is provided in the narrow portion 6a2.

With such a current interruption mechanism, when the positive electrode tab portion 4c is welded to the connection portion 6b of the positive electrode current collector 6, it is possible to suppress adverse effects on the weak portion (part to be broken) provided in the base portion 6a and the connection portion between the deformable plate 61 and the base portion 6a. For example, it is possible to suppress the scattering of spatter generated when welding the connection portion 6b and the positive electrode tab portion 4c onto the weak portion or the connection portion. Alternatively, it is possible to suppress deformation of the weak portion or the periphery of the connection portion in the base portion 6a due to stress when welding the connection portion 6b and the positive electrode tab portion 4c. Note that it is preferable that the relationship between the width W1 of the wide portion 6a1 and the width W2 of the narrow portion 6a2 is W1/W2≧3/2 or more.

The current interruption mechanism of this configuration is also effective when the electrode body housed in the rectangular exterior body is a single wound electrode body. The current interruption mechanism of this configuration is also effective when the electrode body housed in the rectangular exterior body is a stacked electrode body.

A battery pack using multiple rectangular secondary batteries 20 can have the following configuration:

As shown in FIG. 24 , in the battery pack 50, a plurality of prismatic secondary batteries 20 are stacked between a pair of end plates 51 with their large area side walls parallel to each other. The pair of end plates 51 are connected by a bind bar 52. The end plates and the bus bar are connected by means of bolts, rivets, or welding. An insulating separator 53 is disposed between each pair of prismatic secondary batteries 20. The separator 53 is preferably made of resin. In the battery pack 50, the positive electrode terminal 7 and the negative electrode terminal 9 of each prismatic secondary battery 20 are disposed on one side (the side on the front side in FIG. 24 ). The terminals of adjacent prismatic secondary batteries 20 are connected by a bus bar 54. The bottom of each prismatic secondary battery 20 is disposed on the other side (the side on the back side in FIG. 24 ). The small area side walls of each prismatic secondary battery 20 are disposed on the upper and lower surfaces of the battery pack 50. Such a configuration results in a battery pack that is low in height and has a very high volumetric energy density. By mounting such a battery pack 50 on a vehicle in the orientation shown in Fig. 24, the vehicle can have significantly improved interior comfort.

It is preferable that a cooling plate 55 through which a cooling medium flows is disposed on the bottom surface of the battery pack 50, and that each of the rectangular secondary batteries 20 is cooled by this cooling plate. The cooling medium may be either a gas or a liquid.

1: rectangular exterior body 1a: bottom 1b: large area side wall 1c: small area side wall 2: sealing plate 3: wound electrode body 4: positive electrode plate 4a: positive electrode active material layer 4b: positive electrode core exposed portion 4c: positive electrode tab portion 5: negative electrode plate 5a: negative electrode active material layer 5b: negative electrode core exposed portion 5c: negative electrode tab portion 6: positive electrode collector 6a: base portion 6b: connection portion 6c: through hole 7: positive electrode terminal 7a: flange portion 7b: insertion portion 8: negative electrode collector 8a: base portion 8b: connection portion 8c: through hole 9: negative electrode terminal 9a: flange portion 9b: insertion portion 10, 12: insulating member 11, Reference Signs List 13: Gasket 14: Insulating sheet 15: Electrolyte injection hole 16: Sealing plug 17: Gas exhaust valve 20: Prismatic secondary battery 30: Welded portion 31: Straight portion 32: Curved portion 33: Step portion 34: Protrusion 35: Slit 40: Resistance welding electrode 41: Current collector receiving part 42: Spacer 50: Battery pack 51: End plate 52: Bind bar 53: Separator 54: Bus bar 55: Cooling plate 60: Conductive member 61: Deformable plate 62: Insulating plate 63: Through hole 64: Thin portion 65: Groove portion 66: Fixing through hole 67: Fixing protrusion

Claims (14)

an electrode assembly having a separator between a positive electrode plate and a negative electrode plate;
A rectangular exterior body having an opening and housing the electrode body;
A sealing plate that seals the opening;
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 electrically connecting the negative electrode plate and the negative electrode terminal,
the electrode body has a positive electrode tab portion and a negative electrode tab portion at one end facing the sealing plate,
Each of the plurality of electrode assemblies is housed in the rectangular exterior body such that the positive electrode tab portion and the negative electrode tab portion are located at the one end portion,
The positive electrode plate is independent for each electrode body,
The negative electrode plate is independent for each electrode body,
the plurality of electrode bodies include a first electrode body and a second electrode body,
a first positive electrode side welded portion in which the plurality of positive electrode tab portions of the first electrode body are bundled and welded to the positive electrode current collector;
a second positive electrode side weld portion in which the plurality of positive electrode tab portions of the second electrode body are bundled together 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 positions spaced apart in a direction in which the at least two electrode bodies are arranged,
the first positive electrode side welded portion and the second positive electrode side welded portion are aligned with a connection position of the positive electrode current collector with the positive electrode terminal in a longitudinal direction of the sealing plate;
Prismatic secondary battery. A plurality of the negative electrode tab portions are bundled together, sandwiched between the negative electrode current collector and a negative electrode current collector receiving part, and connected to the negative electrode current collector.
The prismatic secondary battery according to claim 1 . A plurality of the positive electrode tab portions are bundled together and sandwiched between the positive electrode current collector and a positive electrode current collector receiving part and connected to the positive electrode current collector.
The prismatic secondary battery according to claim 1 or 2. the negative electrode current collector has a base portion and a connection 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;
the negative electrode tab portion is connected to the connection portion of the negative electrode current collector;
The prismatic secondary battery according to any one of claims 1 to 3. the positive electrode current collector has a base portion and a connection 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;
The positive electrode tab portion is connected to the connection portion of the positive electrode current collector.
The prismatic secondary battery according to any one of claims 1 to 4. The width of the negative electrode tab portion is ¼ to ½ of the width of the electrode body.
The prismatic secondary battery according to any one of claims 1 to 5. The width of the positive electrode tab portion is ¼ to ½ of the width of the electrode body.
The prismatic secondary battery according to any one of claims 1 to 6. The negative electrode plate has a negative electrode core and a negative electrode active material layer formed on the negative electrode core,
the negative electrode core has a negative electrode core exposed portion on which the negative electrode active material layer is not formed,
The negative electrode tab portion is the negative electrode core exposed portion.
The prismatic secondary battery according to any one of claims 1 to 6. 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 a positive electrode core exposed portion on which the positive electrode active material layer is not formed,
The positive electrode tab portion is the positive electrode core exposed portion.
The prismatic secondary battery according to any one of claims 1 to 8. a first negative electrode side welded portion in which the plurality of negative electrode tab portions of the first electrode body are bundled and welded to the negative electrode current collector;
a second negative electrode side welded portion in which the negative electrode tab portions of the second electrode body are bundled together 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 positions separated from each other.
The prismatic secondary battery according to any one of claims 1 to 9. an electrode assembly having a separator between a positive electrode plate and a negative electrode plate;
A rectangular exterior body having an opening and housing the electrode body;
A sealing plate that seals the opening;
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 electrically connecting the negative electrode plate and the negative electrode terminal,
the electrode body has a positive electrode tab portion and a negative electrode tab portion at one end facing the sealing plate,
Each of the plurality of electrode bodies is housed in the rectangular exterior body such that the positive electrode tab portion and the negative electrode tab portion are located at the one end,
The positive electrode plate is independent for each electrode body,
The negative electrode plate is independent for each electrode body,
the plurality of electrode bodies include a first electrode body and a second electrode body,
a first negative electrode side welded portion in which the plurality of negative electrode tab portions of the first electrode body are bundled and welded to the negative electrode current collector;
a second negative electrode side weld portion in which the plurality of negative electrode tab portions of the second electrode body are bundled together 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 positions spaced apart from each other in a direction in which the plurality of electrode assemblies are arranged,
the first negative electrode side welded portion and the second negative electrode side welded portion are aligned with a connection position of the negative electrode current collector with the negative electrode terminal in a longitudinal direction of the sealing plate;
Prismatic secondary battery. The rectangular 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 sidewall is smaller than the area of the large area sidewall;
the area of the bottom is smaller than the area of the small area sidewall;
The prismatic secondary battery according to any one of claims 1 to 11. A battery pack including a plurality of prismatic secondary batteries according to any one of claims 1 to 12,
A pair of end plates;
a bind bar connecting the pair of end plates,
The plurality of rectangular secondary batteries are arranged between the pair of end plates. A battery pack including a plurality of the prismatic secondary batteries according to claim 12,
A pair of end plates;
a bind bar connecting the pair of end plates,
the plurality of prismatic secondary batteries are arranged between the pair of end plates with the large-area side walls of each of the prismatic secondary batteries oriented in parallel;
The positive electrode terminal and the negative electrode terminal of each of the rectangular secondary batteries are disposed on one side surface,
The bottoms of the rectangular exterior bodies of the rectangular secondary batteries are disposed on the other side of the battery pack.