JP2001102030A - Electric energy accumulation device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve current collecting efficiency of the secondary battery such as Li-ion batteries, which extracts electric powers, generated by wound electrodes 4 from the positive and negative terminals thereof to the outside. SOLUTION: The electric energy accumulation device comprises a wound electrode body 4 having protruding ends of one of positive or negative terminal extended from one of both ends of the wound electrode 4 along the axial direction of the winding; and a resilient metallic corrugated sheet 6 arranged at the spiral space formed between the protruding end in a spiral winding shape, wherein one end surface 42 of the electrode body 4 is formed by the protruding end and one end of the corrugated sheet 6. The end surface 42 of the electrode body is joined by rear surface of the current collecting plate and this charge collecting plate is connected with the other positive or negative terminal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electric double layer capacitor, a lithium ion secondary battery and the like which are used as a power source for an igniter of a gasoline vehicle, a storage device for storing regenerative braking energy of a hybrid vehicle or an electric vehicle, and the like. The structure of the electric energy storage device.

[0002]

2. Description of the Related Art As shown in FIG. 11, for example, a conventional lithium ion secondary battery has an insulating member (1) at an opening of a negative electrode can (10).
A sealed container (1) is formed by fixing the sealing plate (11) through the sealing plate (2), and the wound electrode body (2) is accommodated inside the sealed container (1), and the sealing plate (11) is provided. A positive electrode terminal (13) incorporating a gas discharge valve (14) is attached to 11). As a result, the electric power generated by the winding electrode body (2) is transferred to the positive electrode terminal (1).
3) and can be taken out from the negative electrode can (10).

As shown in FIG. 12, the wound electrode body (2) comprises a strip-shaped positive electrode (21), a separator (22), and a negative electrode (23). The positive electrode (21) is formed by applying a positive electrode active material (24) to the surface of a core (25) made of aluminum foil, and the negative electrode (23) is formed by coating the negative electrode on the surface of a core (27) made of copper foil. It is configured by applying an active material (26). The positive electrode (21) and the negative electrode (23) are superimposed on the separator (22) while being shifted in the width direction, and are wound in a spiral shape. With this, at one end of the two ends in the winding axis direction of the winding electrode body (2), the edge of the positive electrode (21) projects outward from the edge of the separator (22), At the other end,
The edge of the negative electrode (23) projects outward from the edge of the separator (22). For example, the width A of the active material coated portion of each electrode is several tens of mm, the width B of the non-coated portion is several mm, and the projection distance S from the separator (22) is about 1 to 3 mm.

As shown in FIG. 11, current collecting plates (3) are provided at both ends of the wound electrode body (2). The current collector plate (3) includes a flat plate portion (33) joined to the end surface of the wound electrode body (2) and a tab portion (3) protruding from the surface of the flat plate portion (33).
2), the tip of the tab portion (32) of the current collector plate (3) on the positive electrode side,
The tip of the tab portion (32) of the current collector plate (3) on the negative electrode side is welded to the inner surface of the sealing plate (11) and the bottom surface of the negative electrode can (10).

[0005]

By the way, in a lithium ion secondary battery, in order to enable charging and discharging with a large current, a current from the winding electrode body (2) to the positive terminal and the negative terminal is required. It is necessary to reduce the electric resistance of the path as much as possible to increase the current collection efficiency. However, FIG.
In the conventional lithium ion secondary battery shown in FIG. 1, the edge of the core of the winding electrode body (2) is connected to the flat plate portion (3
3) The structure is abutted against
The contact area between the core edge of (2) and the current collector (3) is small,
As a result, there has been a problem that the contact resistance increases and the current collection efficiency decreases.

The core constituting each electrode of the wound electrode body (2) is very thin, for example, several tens of microns, and has low strength. ) By resistance welding, when the current collector plate (3) is strongly pressed against the core body edge, the core body edge is crushed, and the core body edge and the back surface of the current collector plate (3) Do not adhere sufficiently, resulting in poor welding, increasing the contact resistance between the wound electrode body (2) and the current collector plate (3), and causing a problem of lowering the current collection efficiency. Was. Furthermore, even with good welding, there is a risk of contacting the opposite electrode edge if the core edge is crushed too much.

An object of the present invention is to reduce the contact resistance between an electrode body and a current collecting plate in an electric energy storage device such as a lithium ion secondary battery, thereby improving the current collecting efficiency as compared with the related art.

[0008]

In the electric energy storage device according to the present invention, a separator (22) is interposed between a strip-shaped positive electrode (21) and a strip-shaped negative electrode (23) in a closed container (1). The wound electrode body (4) is accommodated, and the electric power generated by the wound electrode body (4) can be taken out from the positive electrode terminal portion and the negative electrode terminal portion provided in the closed container. Here, the edge of one of the positive electrode (21) and the negative electrode (23) protrudes from at least one end of both ends in the winding axis direction of the winding electrode body (4). In the spiral space formed by the protruding portion of the electrode, a metal corrugated member (6) having elasticity in the spiral direction is provided in a spirally wound state, and the edge of the electrode and the corrugated member are provided. The edge of (6) forms an electrode body end face (42). The electrode body end face (4
The back surface of the current collector plate (5) is joined to 2), and the current collector plate (5) is connected to the positive electrode terminal portion or the negative electrode terminal portion.

In the electric energy storage device of the present invention, the electrode body end face (42) is in contact with the edge of the electrode and the corrugated plate member.
Since the electrode body is formed by the edge of (6), the distance between the electrode body end face (42) and the back surface of the current collector plate (3) is lower than in the conventional case where the electrode body end face is formed only by the electrode edge. The contact area increases, thereby reducing the contact resistance between the two and improving the current collection efficiency.

A spiral corrugated member (6) made of metal is buried in the spiral space formed by the electrode end of the winding electrode body (4), and the electrode end is corrugated (6). Even if the electrode core is thin, the electrode edge is pushed by the current collector plate (3) in the process of pressing the current collector plate (3) against the electrode edge and performing resistance welding. The electrode body end surface (42) and the back surface of the current collector plate (3) are securely adhered without being crushed. As a result, the end face (42) of the electrode body and the current collector (3) are welded to each other with a large contact area.
The contact resistance between (4) and the current collecting plate (3) is reduced, and the current collecting efficiency is improved.

In a specific configuration, a positive electrode (21) and a negative electrode (2
3) is formed by applying an active material to the surface of the strip-shaped core body, and at least at one end of the one electrode, an uncoated portion to which the active material is not applied is formed. A corrugated plate member (6) is joined to the plate. In the specific configuration,
Since the corrugated plate member (6) is joined to the uncoated portion of the core constituting the electrode, the core and the corrugated plate member (6) come into direct contact, and the contact resistance between the two is reduced. It will be small.

In a more specific configuration, a plurality of projections (51) are formed on the back surface of the current collector (5), and these projections (5) are formed.
The tip surface of 1) is resistance-welded to the electrode body end surface (42). According to the specific configuration, the current collector plate (5) is connected to the electrode body end surface (4).
By pressing against 2), the protrusion (51) of the current collector (5)
Is strongly pressed against the electrode body end face (42), and a current at the time of resistance welding flows through the pressed part, so that the current collector plate (5) is securely connected to the electrode body end face (42).
To be welded. At this time, the electrode body end surface (42) is corrugated plate member (6).
It is not crushed because it is reinforced.

The present invention is also applicable to an electric energy storage device in which an electrode body is formed by laminating a positive electrode, a separator and a negative electrode. In this case, the electrode body (4)
The edge of either one of the positive electrode (21) and the negative electrode (23) protrudes at the end of the corrugated metal sheet member (6) between the electrode surfaces facing each other. Is provided, and an electrode body end face (42) is formed by the edge of the electrode and the edge of the corrugated plate member (6). Then, the back surface of the current collector plate (5) is joined to the electrode body end surface (42), and the current collector plate (5) is connected to the positive electrode terminal portion or the negative electrode terminal portion.

[0014]

According to the electric energy storage device of the present invention, the contact resistance between the electrode body and the current collecting plate can be reduced, and the current collecting efficiency can be improved as compared with the prior art.

[0015]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, an embodiment in which the present invention is applied to a lithium ion secondary battery will be specifically described with reference to FIGS. As shown in FIG. 1, the lithium ion secondary battery according to the present invention has an insulating member (1) at the opening of the negative electrode can (10).
The sealing plate (11) is caulked and fixed via 2), and the sealed container (1)
The wound electrode body (4) is accommodated in the closed container (1). Further, a positive electrode terminal (13) having a built-in gas discharge valve (14) is attached to the sealing plate (11).

A current collecting plate (5) is joined to each of a pair of positive and negative electrode end surfaces (42) formed at both ends of the wound electrode body (4), and a current collecting plate ( The tip of the tab (52) extending from 5) is joined to the back surface of the sealing plate (11), and the current collector plate on the negative electrode side
The tip of the tab portion (52) extending from (5) is joined to the bottom surface of the negative electrode can (10). Thereby, the electric power generated by the winding electrode body (4) can be taken out from the positive electrode terminal (13) and the negative electrode can (10).

As shown in FIGS. 6 and 7, the wound electrode body (4) has a strip-shaped positive electrode (21) and separators (22) and (22).
And the negative electrode (23), the positive electrode (21) and the negative electrode (23) are respectively superposed on the separator (22) while being shifted in the width direction,
After being wound in a spiral around the winding core (41), the winding core
(41) is extracted and completed.

The positive electrode (21) is a core made of aluminum foil.
(25) is coated with a positive electrode active material (24).
As shown in FIG. 7, an uncoated portion where the positive electrode active material is not applied is formed along one edge extending in the electrode longitudinal direction, and the non-coated portion is made of an aluminum corrugated member.
(6) is installed and ultrasonically welded at a plurality of locations in the longitudinal direction. On the other hand, the negative electrode (23) is formed by applying a negative electrode active material (26) on the surface of a core (27) made of copper foil, and as shown in FIGS. 6 and 7, the other end extending in the longitudinal direction of the electrode. Along the edge, a non-coated portion where the negative electrode active material is not applied is formed, and a copper corrugated plate member (6) is installed on the non-coated portion, and ultrasonic welding is performed at a plurality of locations in the longitudinal direction. ing.

Each of the corrugated sheet members (6) is formed by press-forming a metal foil into a waveform in a direction of exhibiting elasticity in the winding direction of the electrode. For example, on the positive electrode side shown in FIG. 4, it has a size substantially equal to the distance between the opposing surfaces of the core body (25) constituting the positive electrode (21) wound in a spiral shape. Therefore, the corrugated sheet member
(6) is installed spirally along the spiral space formed by the core projecting from each end of the winding electrode body (4), and each electrode end is provided with a core. Body edge and corrugated sheet
An electrode body end face (42) having the edge of (6) aligned with one plane is formed.

In a state where the electrodes (positive electrode (21) and negative electrode (23)) are developed in a flat plate shape as shown in FIG. 5, a corrugated plate member (6) is joined to a non-coated portion of the electrode. In the step of winding the electrode as shown in FIG. 6, the corrugated sheet member (6) has elasticity in the electrode winding direction. Is absorbed. Therefore, without applying excessive force to the electrodes and the corrugated plate member (6),
Winding can be performed easily. Further, there is an effect that the imbalance of the winding tension on the side with and without the corrugated sheet member 6 in the winding width direction is absorbed and the winding deviation is suppressed.

FIG. 2 shows the end face (42) of the positive electrode side of the wound electrode body (4).
The spiral pattern formed by the positive electrode core (25) and the spiral pattern formed by the edge of the corrugated plate member (6) appear. Negative electrode end face
A similar spiral pattern appears in (42).

The end surface (4) of each electrode body of the winding electrode body (4)
In (2), a current collecting plate (5) as shown in FIG. 8 is installed. The current collector plate (5) includes a circular flat plate portion (50), and the flat plate portion (50) has a plurality of protrusions (5
1) is formed, and a tab (52) is protruded from an end of the flat plate (50). The current collector plate (5) to be installed on the positive electrode side is made of aluminum, and the current collector plate (5) to be installed on the negative electrode side.
Is made of copper.

The current collector plate 5 shown in FIG. 8 is turned upside down as shown in FIG. 9 and placed on the electrode end face 42 of the winding electrode body 4, and the current collector plate 5 shown in FIG. 5) is pressed against the electrode body end face (42). Here, even if the core (25) of the wound electrode body (4) is a thin one having a thickness of several tens μm or less, the end of the core (25) is reinforced by the corrugated plate member (6). Because it is a core (25)
Is not crushed, and the electrode body end surface (42) remains substantially flat. Therefore, the plurality of projections (51) of the current collector plate (5)
The front end face is pressed against the edge of the core body (25) and the edge of the corrugated plate member (6), and is joined to these edges with a large contact area.

In this state, a pair of resistance welding electrode rods (not shown) are brought into contact with the surface of the flat plate portion (50) of the current collector plate (5) across the slit (53), and Current collector plate (5) is resistance-welded to the electrode body end face (42).
Here, all the projections (51) of the current collector plate (5) are pressed against the edge of the core (25) of the winding electrode body (4) and the edge of the corrugated plate member (6). As a result, good resistance welding is performed over all of the projections (51), and as a result, the current collector plate (5) has a large contact area on the electrode body end surface (42) of the winding electrode body (4). Is securely joined.

Thereafter, as shown in FIG. 1, the current collector plate on the positive electrode side
The tip of the tab (52) of (5) is welded to the back surface of the sealing plate (11), and the tip of the tab (52) of the current collector (5) on the negative electrode side is attached to the bottom of the negative electrode can (10). Weld and assemble the battery. Since each current collector plate (5) is provided with a plurality of round holes formed by protrusions (51) and one slit (53), the current collector plate (5) is closed in the electrolyte injection step after the battery is sealed. The electrolytic solution injected into the container (1) is wound up without being blocked by the current collector plate (5).
It is supplied to (4) and impregnated in the separator (22).

As described above, according to the lithium ion secondary battery of the present invention, the wound electrode body (4) and both current collectors (5)
The contact resistance during (5) is reduced, and the current collection efficiency is improved as compared with the conventional case.

The configuration of each part of the present invention is not limited to the above embodiment, and various modifications can be made within the technical scope described in the claims. For example, the waveform to be formed on the corrugated plate member (6) is not limited to a sine waveform as shown in FIG. 10A, but may be a sawtooth waveform as shown in FIG. 10B or a rectangular waveform as shown in FIG. There may be.

[Brief description of the drawings]

FIG. 1 is a sectional view of a lithium ion secondary battery according to the present invention.

FIG. 2 is a perspective view of a wound electrode body.

FIG. 3 is an enlarged cross-sectional view of a state in which a current collector is pressed against an end face of an electrode body of a wound electrode body.

FIG. 4 is a cross-sectional shape of an end of an electrode body on which a corrugated plate member is installed;
FIG. 3 is a diagram showing a planar shape of the corrugated plate member.

FIG. 5 is a perspective view showing a positive electrode and a corrugated member before joining.

FIG. 6 is a perspective view showing a winding step of a winding electrode body.

FIG. 7 is a partially developed plan view of a winding electrode body.

FIG. 8 is a perspective view of the back side of the current collector plate.

FIG. 9 is a perspective view of a step of installing a current collector on an end face of the electrode body of the wound electrode body.

FIG. 10 is a diagram showing various waveforms to be formed on a corrugated plate member.

FIG. 11 is a cross-sectional view of a conventional lithium ion secondary battery.

FIG. 12 is a partially developed perspective view of a wound electrode body.

[Explanation of symbols]

 (10) Negative electrode can (11) Seal plate (13) Positive electrode terminal (4) Winding electrode body (21) Positive electrode (22) Separator (23) Negative electrode (24) Positive electrode active material (25) Core (26) Negative electrode active Material (27) Core (42) End of electrode body (5) Current collector (6) Corrugated plate member

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H022 AA09 AA18 BB11 CC12 CC13 CC20 5H029 AJ02 AJ06 BJ12 BJ14 CJ07 CJ22 DJ05 DJ07

Claims (4)

[Claims] 1. A strip-shaped positive electrode is provided in a closed container (1).
The separator (22) is interposed between (21) and the negative electrode (23), and the electrode body (4) formed by laminating or winding these is accommodated, and the power generated by the electrode body (4) is sealed. In an electric energy storage device capable of being taken out from a positive electrode terminal portion and a negative electrode terminal portion provided in a container, one of a positive electrode (21) and a negative electrode (23) is provided at an end of the electrode body (4). An edge of the electrode protrudes, and a metal corrugated plate member (6) is provided between the electrode surfaces facing each other at the protruding portion, and the edge of the electrode and the edge of the corrugated plate member (6) are provided. Electrode end face (4
2) is formed, the back surface of the current collector plate (5) is joined to the electrode body end surface (42), and the current collector plate (5) is connected to the positive electrode terminal portion or the negative electrode terminal portion. Characteristic electric energy storage device. 2. A band-shaped positive electrode is provided in a closed container (1).
A winding electrode body (4) having a separator (22) interposed between (21) and the negative electrode (23) is accommodated, and the winding electrode body (4)
In the electric energy storage device capable of taking out the electric power generated from the positive electrode terminal portion and the negative electrode terminal portion provided in the sealed container to the outside, the winding electrode body (4) includes: At least at one end, the edge of either the positive electrode (21) or the negative electrode (23) protrudes, and the spiral space formed by the protruding portion of the electrode has elasticity in the spiral direction. A metal corrugated plate member (6) is spirally wound and provided, and the electrode body end surface (42) is formed by the edge of the electrode and the edge of the corrugated plate member (6).
Is formed, the back surface of the current collector plate (5) is joined to the electrode body end surface (42), and the current collector plate (5) is connected to the positive electrode terminal portion or the negative electrode terminal portion. Electrical energy storage device. 3. The positive electrode (21) and the negative electrode (23) are each formed by applying an active material to the surface of a strip-shaped core, and at least the end of the one electrode is not coated with the active material. The electric energy storage device according to claim 1 or 2, wherein a non-coated portion is formed, and a corrugated plate member (6) is joined to the non-coated portion. 4. A plurality of projections (51) are provided on the back surface of the current collector plate (5).
The electric energy storage device according to any one of claims 1 to 3, wherein a tip surface of each of the projections (51) is welded to the electrode body end surface (42).