JP2003272600A - Secondary battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To more reduce internal resistance than an existing secondary battery and increase the output per volume in a secondary battery having current collecting structure in which a current collecting plate is installed at the end part of a wound electrode body. <P>SOLUTION: In this secondary battery, an end edge 48 of a belt-shaped core constituting a positive electrode or a negative electrode is protruded at either one end of the wound electrode body 4, and the current collecting plate 50 is installed so as to cover the end edge 48. An electrode terminal mechanism 90 has an electrode terminal 91 passing through a battery can 1, and a flange 92 pressure-contacted to the surface of the current collecting plate 50 and a screw shaft piece 97 protruding to the wound electrode body 4 side from the flange 92 are installed in the electrode terminal 91. A cylinder boss 56 closely fitting to a central hole 40 of the wound electrode body 4 is protruded in the current collecting plate 50, and the screw shaft piece 97 of the electrode terminal 91 is screwed to an inside screw 57 formed on the inner peripheral surface of the cylinder boss 56. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention accommodates a winding electrode body serving as a secondary battery element inside a battery can, and takes out the power generated by the winding electrode body from a pair of electrode terminal portions provided on the battery can. The present invention relates to a secondary battery that can be used.

[0002]

2. Description of the Related Art In recent years, lithium ion secondary batteries having high energy density have been attracting attention as power sources for portable electronic devices, electric vehicles and the like. For example, a relatively large capacity cylindrical lithium-ion secondary battery used in electric vehicles is
As shown in FIG. 9 and FIG. 10, the lid (1
2) A winding electrode body (4) is housed inside a cylindrical battery can (1) formed by welding and fixing (12). A pair of positive and negative electrode terminal mechanisms (9) and (9) are attached to both lids (12) and (12), and both poles of the winding electrode body (4) and both electrode terminal mechanisms (9) and (9) are attached. Are connected to each other, and the electric power generated by the winding electrode body (4) is supplied to the pair of electrode terminal mechanisms (9) (9).
It is possible to take it out from the outside. Further, a pressure opening / closing type gas discharge valve (13) is attached to each lid (12).

As shown in FIG. 11, the take-up electrode body (4) has a strip-shaped separator (42) interposed between a strip-shaped positive electrode (41) and a strip-shaped negative electrode (43) to form a spiral shape. It is made up by winding. The positive electrode (41) is formed by applying a positive electrode active material (44) made of a lithium composite oxide on both surfaces of a strip-shaped core body (45) made of aluminum foil, and the negative electrode (43) is a strip-shaped core made of copper foil. Negative electrode active material containing carbon material on both sides of body (47)
It is formed by applying (46). The separator (42) includes
It is impregnated with a non-aqueous electrolyte.

Here, the positive electrode (41) and the negative electrode (43) are stacked on the separator (42) while being shifted in the width direction, and wound in a spiral shape. As a result, one of the two ends of the winding electrode body (4) in the winding axis direction is
Positive electrode (41) core (45) outward from the edge of the separator (42)
Of the core body (47) of the negative electrode (43) outward from the edge of the separator (42) while the edge (48) of the negative electrode (48) projects.
(48) is protruding. A disk-shaped current collector plate (5) is welded to both ends of the winding electrode body (4), and strip-shaped lead portions (55) projecting from the current collector plate (5) are illustrated. It is connected to the base end of the electrode terminal mechanism (9) shown in FIG.

The electrode terminal mechanism (9) is a cover (1) for the battery can (1).
The electrode terminal (91) is attached so as to penetrate through 2), and a flange (92) is formed at the base end of the electrode terminal (91). An insulating packing (93) is attached to the through hole of the lid body (12) to maintain electrical insulation and sealing between the lid body (12) and the fastening member (91). A washer (94) is fitted to the electrode terminal (91) from the outside of the lid body (12), and a first nut (9
5) and the second nut (96) are screwed together. Then, the first nut (95) is tightened and the insulating packing (93) is pinched by the flange (92) of the electrode terminal (91) and the washer (94) to improve the sealing property. The current collector plate (5)
Of the electrode terminal (91) flange (9
It is fixed to 2) by spot welding or ultrasonic welding.

By the way, particularly in a lithium ion secondary battery used as a power source for an electric vehicle or the like, it is necessary to reduce the internal resistance as much as possible in order to obtain a high capacity and a high output. Therefore, in order to reduce the internal resistance of the secondary battery, in the current collecting structure shown in FIG. 11, the flat body (51) of the current collecting plate (5) extends radially around the central hole (54). A plurality of arc-shaped convex portions (52) are integrally molded and project to the winding electrode body (4) side. Further, in the flat plate-shaped main body (51), a plurality of cut-and-raised pieces (53) are formed between the adjacent arc-shaped convex portions (52) (52), respectively, and the winding electrode body (4) side Overhangs.

In the manufacturing process of the secondary battery having the current collecting structure, the current collecting plate (5) is pressed against the core body edge (48) formed at the end of the winding electrode body (4). As a result, the arcuate convex portion (52) of the current collector plate (5) is
(4) It bites into the core body edge (48), and a joining surface made of a cylindrical surface is formed between the arcuate convex portion (52) and the core body edge (48). Further, the cut-and-raised piece (53) of the current collector plate (5) deeply digs into the core body edge (48) of the winding electrode body (4) and press-bonds with the core body edge (48). .

In this state, the arcuate convex portion (52) of the current collector plate (5)
A laser beam is irradiated toward the inner peripheral surface of the to perform laser welding. As a result, the arcuate convex portion (52) of the current collector plate (5) and the core body edge (48) of the winding electrode body (4) are joined to each other with a large contact area, and the cut-and-raised piece is also formed. (53) and core edge (48)
The pressure-bonded state between them will be maintained.

Therefore, the current collector plate (5) has the arcuate convex portions (52).
With a large contact area at the welded portion of the core edge (48) with the core edge
While being joined to (48), in a region other than the welded portion, each cut-and-raised piece (53) bites into the core body edge (48), and a good contact state is obtained, so that the current collector plate ( 5) and winding electrode body
The contact resistance between (4) becomes small. However, due to the plurality of cut and raised pieces (53) formed on the current collector plate (5), the edge of the core body is
Since current is collected from all over (48), high current collecting performance can be obtained.

[0010]

However, as shown in FIG.
In the current collecting structure in which the lead portion (55) protruding from the current collecting plate (5) is connected to the electrode terminal mechanism (9) as shown in FIG.
Electrode terminal mechanism from (4) via lead part (55) of current collector (5)
In the current path to (9), the flat body of the current collector (5)
Since the lead portion (55) extending from the end of (51) to the electrode terminal (91) is long and its cross-sectional area is small, the electric resistance of the current path formed by the lead portion (55) is large. However, there was a problem that the internal resistance could not be reduced sufficiently.

Further, it is necessary to provide a space for extending the lead portion (55) between the current collector plate (5) in the battery can (1) and the electrode terminal (91) of the electrode terminal mechanism (9). However, the volume of the battery can (1) becomes large and the output per unit volume of the secondary battery is small.

Therefore, an object of the present invention is to further reduce the internal resistance and increase the output per unit volume in a secondary battery having a current collecting structure using a current collecting plate.

[0013]

In a secondary battery according to the present invention, a strip-shaped positive electrode (41) is provided inside a battery can (1).
The separator (42) is interposed between the negative electrode (43) and the negative electrode (43) to house the spirally wound winding electrode body (4), and the positive electrode (41)
The negative electrode (43) is formed by applying an active material to the surface of the strip-shaped core body, and the electric power generated by the winding electrode body (4) can be taken out from the pair of electrode terminal portions to the outside. At least one end of the winding electrode body (4),
Edge (48) of the strip-shaped core that constitutes the positive electrode (41) or the negative electrode (43)
Is projected, a current collector plate (50) is installed to cover the edge (48),
The current collector plate (50) is connected to one of the electrode terminal portions.
Further, the current collector plate (50) has a central hole of the winding electrode body (4).
A boss (56) tightly fitted into the (40) is provided in a protruding manner, and an end portion of the one electrode terminal portion projects into the boss (56) so that the boss (56)
The end portion of the electrode terminal portion is pressed against the surface of the current collector plate (50) in the vicinity of the fixed position.

In the above-mentioned secondary battery of the present invention, the end portion of the electrode terminal portion is directly brought into pressure contact with the surface of the collector plate (50) to form a current path from the winding electrode body (4) to the electrode terminal. Since it is formed and there is no intervening lead portion as in the conventional case, the electric resistance of the current path is small. Further, in order to fix the end of the electrode terminal portion to the surface of the current collector plate (50) in a pressure contact state, inside the boss (56) fitted into the central hole (40) of the winding electrode body (4), Since the structure of fixing the end portion of the electrode terminal portion to the current collector plate (50) is adopted, the fixing structure is the winding electrode body.
Since it is housed inside the central hole (40) of (4), an extra space for arranging the fixing structure is unnecessary.

In a specific configuration, the one electrode terminal portion includes an electrode terminal (91) penetrating the battery can (1), and the electrode terminal (91) is provided on the surface of the current collector plate (50). A flange (92) to be pressed and a winding electrode body (4) wound from the flange (92)
A screw shaft piece (97) protruding toward the side is formed, and the current collector plate (5
The screw shaft piece (97) of the electrode terminal (91) is screwed into the inner screw (57) formed on the inner peripheral surface of the boss (56) of (0).

In the process of assembling the secondary battery having the specific structure, the collector plate is inserted into the central hole (40) of the winding electrode body (4).
After welding the current collector plate (50) to the core body end edge (48) of the winding electrode body (4) with the boss (56) of the (50) fitted, the current collector plate (50) To the inner screw (57) of the boss (56) of the electrode terminal (91)
Screw in the screw shaft piece (97) and attach the flange (92) to the collector plate (50).
Press it against the surface of. As a result, the flange (92) of the electrode terminal (91) is directly pressed against the surface of the current collector plate (50) over a wide area, and the electrode is wound from the winding electrode body (4) through the current collector plate (50). The shortest current path to the terminal (91) is formed. As a result, the electric resistance of the current path becomes smaller than in the conventional case.

[0017]

According to the secondary battery of the present invention, it is possible to further reduce the internal resistance and increase the output per unit volume as compared with the conventional case.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention is described below.
A concrete explanation of the embodiment of the next battery with reference to the drawings
Revealoverall structure The lithium ion secondary battery according to the present invention is as shown in FIG.
Do not weld and fix the lids (12) and (12) to both ends of the tube (11).
The winding electrode body (4) is placed inside the cylindrical battery can (1)
It is configured to house. Both lids (12) (12) have positive and negative
A pair of electrode terminal mechanisms (90) (90) are attached. Each lid
The body (12) is fitted with a pressure opening / closing type gas discharge valve (13).
ing. Both ends of the winding electrode body (4) collect current.
The plate (50) is installed and laser welded to the core edge (48).
It The surface of the current collector plate (50) constitutes an electrode terminal mechanism (90).
It is pressed against the flange (92) of the electrode terminal (91).

[0019]Winding electrode body (4) As shown in FIG. 11, the winding electrode body (4) is a strip electrode.
A strip separator (42) between the positive electrode (41) and the negative electrode (43)
It is composed by interposing them and winding them spirally.
It The positive electrode (41) is a strip-shaped core body (45) made of aluminum foil.
Positive electrode active material (44) composed of lithium composite oxide on both sides of
The negative electrode (43) is formed by coating, and the negative electrode (43) is a strip-shaped core made of copper foil.
Apply negative electrode active material (46) containing carbon material on both sides of (47)
It is configured. The separator (42) contains a non-aqueous electrolyte.
It is soaked.

The positive electrode (41) is provided with a coated portion coated with the positive electrode active material (44) and a non-coated portion not coated with the positive electrode active material. In addition, the negative electrode (43) also has a negative electrode active material.
The coated part of (46) and the non-coated part to which the negative electrode active material is not coated are formed. The positive electrode (41) and the negative electrode (43) are respectively shifted and overlapped on the separator (42) in the width direction, and the non-coated portions of the positive electrode (41) and the negative electrode (43) are separated from both end edges of the separator (42). Each is projected outward. The winding electrode body (4) is constructed by winding these in a spiral shape. The winding electrode body
In (4), the core body edge (48) of the non-coated portion of the positive electrode (41) is more than the one edge of the separator (42) at one of the two ends in the winding axis direction. Also protrudes outward, and at the other end, the core body edge (48) of the non-coated portion of the negative electrode (43) is the separator.
It projects more outward than the other edge of (42).

[0021]Electrode terminal mechanism (90) The electrode terminal mechanism (90) is a lid for the battery can (1), as shown in FIG.
A battery consisting of bolts mounted through the body (12).
It has a pole terminal (91). At the base end of the electrode terminal (91)
The disk-shaped flange (92) is formed and
On the underside of the coil (92) towards the winding electrode body (4).
The same shaft piece (97) is projected. The through hole in the lid (12) is
The edge packing (93) is attached, and the lid body (12) and the fastening member (91)
The electrical insulation and sealing properties between the two are maintained. Electrode end
A washer (94) is attached to the child (91) from the outside of the lid body (12).
And the first nut (95) and the second nut (96) are screwed together.
is doing. Then tighten the first nut (95) to
The flange (92) of the terminal (91) and the washer (94) provide insulation
The sealing property is improved by pinching the locking (93).
There is.

[0022]Current collecting structure The current collector plate (50) has a disk-shaped main body (51) as shown in FIGS.
The disc-shaped main body (51) includes a plurality of radially extending strips.
The arc-shaped convex portions (52) (four rows in the embodiment) are integrally molded and wound.
It projects toward the scraping electrode body (4). Also, the disc-shaped body (5
1), between the adjacent arc-shaped convex portions (52) (52),
A plurality of (two in the example) cut and raised pieces (53) are formed,
It projects toward the winding electrode body (4). Where
The through holes that are opened when the strips (53) are formed
Functions as a passage. Furthermore, take up the flat body (51).
In the surface facing the electrode body (4), the center of the winding electrode body (4)
A cylindrical boss (56) that can be fitted into the hole (40) is provided so as to project therefrom.
On the inner peripheral surface of the space (56), the screw shaft piece (97) of the electrode terminal (91).
An inner screw (57) that can be screwed with is formed. The positive electrode side
The current collector plate (50) is made of aluminum, and the current collector plate on the negative electrode side
(50) is made of nickel.

[0023]Production method Battery can (1) shown in Fig. 1, electrode terminal mechanism (90), winding power
After making the pole body (4) and the current collector (50) respectively, wind them up.
Cylindrical boss (56) of current collector (50) to the central hole (40) of the electrode body (4)
And the winding electrode as shown in FIGS. 5 and 7.
A current collector plate is attached to the core body edge (48) formed at each end of the body (4).
Press (50). Here, the center of the winding electrode body (4)
The cylindrical boss (56) of the current collector (50) is closely fitted in the hole (40).
Depending on the position of the collector plate (50) with respect to the winding electrode body (4)
The placement will be done automatically.

In this way, the end (4) of the core body of the winding electrode body (4) is
By pressing the current collector plate (50) against 8), the current collector plate (50)
The arc-shaped convex portion (52) of the winding electrode body is as shown in FIG.
(4) It bites into the core body edge (48), and a joining surface made of a cylindrical surface is formed between the arcuate convex portion (52) and the core body edge (48). The cut-and-raised piece (53) of the current collector plate (50) bites deeply into the core body edge (48) of the winding electrode body (4) as shown in FIG.
It will be crimped with the core edge (48).

In this state, as shown by the arrow in FIG. 6, a laser beam is irradiated toward the inner peripheral surface of the arcuate convex portion (52) of the current collector plate (50) to perform laser welding. As a result, current collector (50)
Arcuate convex part (52) and core edge (48) of the winding electrode body (4)
And are joined to each other with a large contact area, and
The pressure-bonded state between the cut-and-raised piece (53) and the end edge (48) of the core body is maintained.

After that, the screw shaft piece (97) of the electrode terminal (91) is screwed into the inner screw (57) of the cylindrical boss (56) of the current collector plate (50), and the flange (92) of the current collector plate (50) is screwed. ) Is a flat plate-shaped body (51) of the current collector plate (5)
Press it against the surface of. In this way the winding electrode body
After fixing the electrode terminals (91) (91) to the current collector plates (50) (50) at both ends of (4), the winding electrode body (4) is attached to the cylindrical body (11) shown in FIG.
House inside. Then, as shown in FIG. 1, after installing the lid body (12) in each opening of the tubular body (11) and assembling the electrode terminal mechanism (90), the lid body (12) is fixed to the tubular body (11) by welding. To do. Finally, after injecting the electrolytic solution into the battery can (1), the safety valve (13) is screwed into each lid (12) to complete the lithium ion secondary battery of the present invention.

In the lithium-on secondary battery, the electrode terminal (91) is attached to the surface of the flat plate-shaped body (51) of the current collector (50).
The flange (92) of is directly pressed against a sufficiently large area,
Electrode terminal (91) from winding electrode body (4) through current collector plate (50)
Since the shortest current path to the current path is formed, the electric resistance of the current path becomes small. Further, the current collector plate (50) is joined to the core body edge (48) with a large contact area at the welding portion of each arcuate convex portion (52) and the core body edge (48), and the welding is performed. In regions other than the parts, the cut-and-raised pieces (53) bite into the core body edge (48) to obtain a good contact state, so that the current collector plate (50) and the winding electrode body (4) are The contact resistance between them becomes small. Of course,
Since a plurality of cut-and-raised pieces (53) formed on the current collector plate (50) collect current from the entire region of the core body edge (48), high current collecting performance can be obtained.

Of course, the screw shaft piece (97) of the electrode terminal (91) and the cylindrical boss (56) of the collector plate (50) are housed in the central hole (40) of the winding electrode body (4). Since the structure for fixing the current collector plate (50) to the electrode terminal (91) is arranged by utilizing the dead space of the central hole (40), an extra space is provided in the battery can (1). Therefore, the output per unit volume of the secondary battery can be increased more than before.

The configuration of each part of the present invention is not limited to the above embodiment, but various modifications can be made within the technical scope described in the claims. For example, the current collecting structure and the electrode terminal mechanism (90) of the present invention shown in FIG. 1 are not limited to the configuration provided at both ends of the winding electrode body (4), but the winding electrode body (4)
It is also possible to adopt a configuration in which the conventional current collecting structure and the electrode terminal mechanism (9) shown in FIG. 10 are provided at only one end and the other end.

[Brief description of drawings]

FIG. 1 is a partially cutaway front view of a secondary battery according to the present invention.

FIG. 2 is an exploded perspective view of a winding electrode body, a current collector plate, and an electrode terminal.

FIG. 3 is a plan view of a current collector plate.

FIG. 4 is an enlarged cross-sectional view showing a main part of a current collector plate.

FIG. 5 is a perspective view of a step of pressing the arcuate convex portion of the current collector plate against the core body edge of the winding electrode body.

FIG. 6 is an enlarged cross-sectional view showing a state where the arcuate convex portion of the current collector plate is pressed against the core body edge of the winding electrode body.

FIG. 7 is a perspective view of a step of pressing the cut-and-raised piece of the current collector plate against the core body edge of the winding electrode body.

FIG. 8 is an enlarged cross-sectional view of a state where a cut-and-raised piece of a current collector plate is pressed against a core body end edge of a winding electrode body.

FIG. 9 is a perspective view showing the appearance of a secondary battery.

FIG. 10 is a partially cutaway front view of a conventional secondary battery.

FIG. 11 is a partially exploded perspective view of a winding electrode body.

[Explanation of symbols]

(1) Battery can (11) Cylindrical body (12) Lid (4) Winding electrode body (40) Central hole (50) Current collector (51) Flat body (52) Circular convex (53) Cut and raised piece (56) Cylindrical boss (57) Inner thread (90) Electrode terminal mechanism (91) Electrode terminal (92) Flange (97) Screw shaft piece

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Toshiyuki Noma             2-5-3 Keihan Hondori, Moriguchi City, Osaka Prefecture             Within Yo Denki Co., Ltd. (72) Inventor Ikuro Ikuro             2-5-3 Keihan Hondori, Moriguchi City, Osaka Prefecture             Within Yo Denki Co., Ltd. F-term (reference) 5H022 AA09 BB02 BB03 CC03 CC13                       CC19 CC21                 5H029 AJ02 AJ06 AK03 AL06 AM01                       BJ02 BJ14 CJ04 CJ05 CJ07                       DJ05 DJ07

Claims (3)

[Claims] 1. A wound electrode body (4) wound in a spiral shape with a separator (42) interposed between a strip-shaped positive electrode (41) and a negative electrode (43) inside a battery can (1). The positive electrode (41) and the negative electrode (43) are each formed by applying an active material to the surface of the strip-shaped core body, and the electric power generated by the winding electrode body (4) is externally supplied from the pair of electrode terminal portions. The end edge (48) of the strip-shaped core body that constitutes the positive electrode (41) or the negative electrode (43) protrudes from at least one end of the winding electrode body (4). A secondary battery in which a current collector plate (50) is installed so as to cover the edge (48), and the current collector plate (50) is connected to one of the electrode terminal portions, wherein the current collector plate (50) is Is the central hole (40) of the winding electrode body (4)
A boss (56) that fits into the boss (56) is provided so that the end portion of the one electrode terminal portion projects into the boss (56) and is fixed to the boss (56). A secondary battery in which an end portion of the terminal portion is pressed against the surface of the current collector plate (50). 2. The one electrode terminal portion includes an electrode terminal (91) penetrating the battery can (1), and the electrode terminal (91) is pressed against the surface of the current collector plate (50). A flange (92) and a screw shaft piece (97) protruding from the flange (92) toward the winding electrode body (4) are formed, and the inner circumference of the boss (56) of the current collector plate (50) is formed. The secondary battery according to claim 1, wherein an inner screw (57) is formed on the surface, and the screw shaft piece (97) is screwed into the inner screw (57). 3. The current collector plate (50) is formed with a plurality of arc-shaped projections (52) projecting toward the core end edge (48) in an arcuate cross section, and the core end edge is formed. A plurality of cut and raised pieces (53) cut and raised toward (48) are formed.
The arc-shaped convex portion (52) is welded to the core body edge (48) in a state where the (52) and the cut and raised piece (53) bite into the core body edge (48). Item 2. The secondary battery according to item 2.