JP2000243372A - Secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve highly efficient discharge performance. SOLUTION: In a secondary battery where a winding electrode body 2 is housed inside a battery can 1 mounted with an electrode terminal mechanism 3, the winding electrode body 2 and the electrode terminal mechanism 3 are mutually electrically connected, and electric power generated by the winding electrode body 2 can be taken out to an external part from the electrode terminal mechanism 3, plural conductive paper strip pieces 4 are projected in a winding shaft directional end part of at least one electrode among a positive electrode and a negative electrode, and the plural conductive paper strip pieces 4 are bent along a winding electrode body end surface to which the edge of the electrode is exposed to form an electrode surface for covering the almost whole area of the end surface. The electrode terminal mechanism 3 has a terminal assembly 32 press-fitted to the electrode surface on the inside of the battery can 1.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery can provided with an electrode terminal mechanism, in which a chargeable / dischargeable winding electrode body is housed, and the winding electrode body and the electrode terminal mechanism are electrically connected to each other. Further, the present invention relates to a secondary battery capable of taking out the electric power generated by the winding electrode body from the electrode terminal mechanism to the outside.

[0002]

2. Description of the Related Art In recent years, lithium secondary batteries having a high energy density have attracted attention as power sources for portable electronic devices, electric vehicles and the like. For example, the cylindrical lithium secondary battery shown in FIG. 6 has a winding electrode inside a cylindrical battery can (1) formed by welding and fixing lids (12) to both openings of a cylinder (11). It is configured to house the body (7). On each lid (12),
An electrode terminal mechanism (6) is attached, and the winding electrode body (7) and each of the electrode terminal mechanisms (6) are connected to each other by a plurality of current collecting tabs (8). The power generated by (7) can be taken out from the pair of electrode terminal mechanisms (6) and (6). Further, a safety valve (13) is attached to the lid (12).

The wound electrode body (7) is provided between a positive electrode (71) containing a lithium composite oxide and a negative electrode (74) containing a carbon material.
With a separator (73) impregnated with a non-aqueous electrolyte interposed,
These are spirally wound. A plurality of current collecting tabs (8) are respectively drawn from the positive electrode (71) and the negative electrode (74) of the winding electrode body (7), and a plurality of current collecting tabs having the same polarity are provided.
The tip (81) of (8) is connected to one electrode terminal mechanism (6). In FIG. 6, for convenience, only a state in which a tip portion of a part of the current collecting tabs is connected to the electrode terminal mechanism (6) is shown, and the other current collecting tabs are connected to the electrode terminal mechanism (6). Illustration of the connected distal end portion is omitted.

The electrode terminal mechanism (6) is provided with a cover (1) of the battery can (1).
The screw member (31) is provided so as to penetrate through 2), and a flange portion (62) is formed at the base end of the screw member (31). An insulating packing (64) is attached to the through hole of the lid (12), and electrical insulation and sealing between the lid (12) and the screw member (31) are maintained. A washer (66) is fitted into the screw member (31) from outside the cylindrical body (11), and a nut (67) is screwed into the screw member (31). The nut (67) is tightened, and the insulating packing (64) is clamped by the flange (62) of the screw member (31) and the washer (66), thereby enhancing the sealing performance. The tip portions (81) of the plurality of current collection tabs (8) are provided with flange portions of the screw members (31).
(62) is fixed by spot welding or ultrasonic welding.

[0005] In particular, secondary batteries used as power sources for portable electronic devices and electric vehicles are required to have high discharge performance. Therefore, as shown in FIG. 7, an electrode material is applied to the surfaces of the two strip-shaped current collectors to form a positive electrode (71) and a negative electrode (74), and an uncoated portion where no electrode material is applied. (72) and (75) are formed, and the base ends of the plurality of current collecting tabs (8) are fixed to the uncoated portions (72) and (75) by laser welding, ultrasonic welding, etc. A secondary battery comprising a body (7) has been proposed (Japanese Patent Application Laid-Open No. 9-306470 [H01M4 / 0
2]).

As shown in FIG. 8, an electrode material is applied to the surfaces of two strip-shaped current collectors to form a positive electrode (91) and a negative electrode (94). Coating Department (9
2) A secondary battery has been proposed in which (95) is formed, and the uncoated portions (92) and (95) are formed into a plurality of strip-shaped leads (80) to form a wound electrode body (9). (Japanese Patent Laid-Open No. 9-92335 [H01M10 / 4
0]).

[0007]

However, in the conventional wound electrode body, the high-rate discharge performance is still insufficient, and a further improvement in the discharge performance is required.
An object of the present invention is to provide a secondary battery capable of obtaining a higher rate discharge performance than a conventional battery.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies to determine the cause of the decrease in the high-rate discharge performance, and as a result, the flange (62) of the electrode terminal mechanism (6) and each Current collection tab (8)
Because of the small contact area, a large electrical resistance is generated at the contact portion, and it has been found that the occurrence of power loss due to this electrical resistance causes a decrease in high-rate discharge performance. Reached.

The secondary battery according to the present invention has an electrode terminal mechanism.
A chargeable / dischargeable winding electrode body (2) is housed inside a battery can (1) to which (3) is attached, and the winding electrode body (2)
Is configured by spirally winding a strip-shaped positive electrode (21) and a negative electrode (24) with a separator (23b) interposed between both electrodes,
The winding electrode body (2) and the electrode terminal mechanism (3) are electrically connected to each other, so that the power generated by the winding electrode body (2) can be taken out of the electrode terminal mechanism (3). is there. In the characteristic configuration of the secondary battery, the positive electrode
At least one of the electrodes (21) and the negative electrode (24) is provided with a plurality of conductive strips (4) and (40) protruding from the end in the winding axis direction, and the plurality of conductive strips are provided. (4) (40) is bent along the end surface of the wound electrode body where the edge of the electrode or the edge of the separator (23b) is exposed to form an electrode surface F covering substantially the entire area of the end surface; The electrode terminal mechanism (3) includes a terminal plate (32) that is crimped to the electrode surface F inside the battery can (1).

In the winding step of the wound electrode body according to the present invention, the positive electrode (21), the separator (23b) and the negative electrode (2
4), for example, both ends of the positive electrode (21) and both ends of the negative electrode (24) are located inside the both ends of the separator (23b), and a plurality of strips (4) (40) are They are overlapped so as to protrude from both ends of 23b), and they are spirally wound. Therefore, the edge of the separator (23b) appears on the end surface of the wound electrode body (2), and the edge of the counter electrode does not appear.

[0011] Then, in the assembly process of the secondary battery,
The plurality of conductive strips (4) and (40) are bent along the end surface of the winding electrode body (2), whereby the plurality of conductive strips (4) and (40) are folded. An electrode surface F that covers substantially the entire end face of 2) is formed. Here, since the edge of the counter electrode does not appear on the end face of the wound electrode body (2) as described above, it is difficult for these conductive strips (4) and (40) to contact the edge of the counter electrode. Absent. After bending the plurality of conductive strips (4) and (40) to form the electrode surface F in this manner, the wound electrode body (2) is housed inside the battery can (1),
The terminal plate (32) of the electrode terminal mechanism (3) is crimped to the electrode surface F. Thereby, a plurality of conductive strips (4) (40)
Are securely connected to the electrode terminal mechanism (3).

In the secondary battery, an electrode terminal mechanism (3)
Of the conductive strips (4) and (40) is pressed against the electrode surface F composed of a plurality of conductive strips (4) and (40), so that the plurality of conductive strips (4) and (40) (32), the electrical resistance at the contact area is small, and the power loss is reduced.
High high rate discharge performance is obtained. Further, in the assembling process of the secondary battery, the troublesome work of welding the tips of the plurality of current collecting tabs (8) to the electrode terminal mechanism (6) is unnecessary, and the terminal plate of the electrode terminal mechanism (3) is unnecessary. Replace (32) with a plurality of conductive strips (4)
The conductive strip (4) can be connected to the electrode terminal mechanism (3) by a simple operation of merely crimping the electrode surface F formed by bending the (40).

More specifically, a plurality of conductive strips (4) and (4)
The electrode protruded from (0) has a strip-shaped current collector, and the current collector has a coating portion on which an electrode material is applied, and is provided at one end in the winding axis direction. Uncoated portions (22) and (25) where no electrode material is applied are formed, and the uncoated portions (22) and (2)
In (5), a plurality of cuts are made in the direction along the winding axis direction, whereby a plurality of conductive strips (4) and (40) are formed over the entire length of the electrode edge.

In the specific configuration, the uncoated portions (22) and (2)
Make multiple cuts in 5) to make a plurality of conductive strips (4) (4).
Since (0) is formed, a troublesome operation of fixing the base ends of the plurality of current collecting tabs (8) to the uncoated portions (72) and (75) by laser welding, ultrasonic welding, or the like is unnecessary. Also conductive strips
(4) Since (40) is formed over the entire length of the electrode edge, the current collecting property of the electrode is extremely uniform, and higher high-rate discharge performance can be obtained.

More specifically, a plurality of conductive strips (4
1) The electrode provided with (42) is provided with a band-shaped current collector, and the current collector is formed with a coated portion to which an electrode material is applied, and has one of the winding axis directions. Uncoated portions (52) and (55) on which the electrode material is not applied are formed at the ends, and the uncoated portions (5
2) The ends of the strip-shaped metal foils (56) and (57) are connected to (55), and a plurality of the metal foils (56) and (57) are By cutting, a plurality of conductive strips (41) and (42) are formed over the entire length of the electrode edge.

In the specific configuration, the uncoated portions (52) (5)
After connecting the ends of the strip-shaped metal foils (56) and (57) to 5), a plurality of cuts are made in the metal foils (56) and (57) to form a plurality of conductive strips (4) and (40). To form Therefore, a troublesome work of fixing the base ends of the plurality of current collecting tabs (8) to the uncoated portions (72) and (75) by laser welding, ultrasonic welding, or the like is unnecessary. The uncoated portions (52) and (55) have a higher mechanical strength due to the connection of the ends of the metal foils (56) and (57). In this case, the breakage of the non-coated portions (52) and (55) can be suppressed, and the yield of the manufacturing process is improved. In addition, since the conductive strips (41) and (42) are formed over the entire length of the edge of the electrode, the current collecting properties of the electrode are extremely uniform, and higher high-rate discharge performance can be obtained.

More specifically, an insulating film (14) is formed on the inner peripheral surface of the battery can (1) at least in a region surrounding the terminal plate (32) of the electrode terminal mechanism (3). I have.

In the specific configuration, an insulating film (14) is formed on the inner peripheral surface of the battery can (1) at least in a region surrounding the terminal plate (32) of the electrode terminal mechanism (3). Therefore, even if vibration or shock is applied from outside, the electrode terminal mechanism (3)
The terminal plate (32) does not directly contact the inner peripheral surface of the battery can (1), and the terminal plate (32) of the electrode terminal mechanism (3) and the battery can (1) are not short-circuited.

A pair of electrode terminal mechanisms (3) and (3) are fixed to both ends of the battery can (1), and each electrode terminal mechanism (3) is
In the configuration in which the terminal plate (32) is provided at the tip end projecting into the battery can (1), the wound electrode body (2) is provided with a pair of terminal plates (32) (32) on both electrode surfaces. Is pressed from both sides and held in the battery can (1).

Specifically, each terminal plate (32) has a flat plate portion formed with a crimping surface capable of engaging with the electrode surface, and is formed on an outer peripheral portion of the flat plate portion, and at least a wound electrode body is formed. And a cylindrical portion surrounding the outermost peripheral surface of the end portion.

In the specific structure, the terminal plate (3) is attached to the electrode surface F constituted by a plurality of conductive strips (4) and (40).
In the step (2) of pressing the flat plate portion, the terminal plate (32) is covered on the end of the wound electrode body (2) so that the cylindrical portion surrounds the outermost peripheral surface of the wound electrode body (2). By doing so, the flat portion of the terminal plate (32) is accurately positioned on the electrode surface, and the flat plate portion of the terminal plate (32) can be securely pressed against the electrode surface F. Further, since both ends of the winding electrode body (2) are respectively held by the cylindrical portions of the respective terminal plates (32), the winding electrode body (2) vibrates due to external vibration or impact. However, the electrode surface F does not shift with respect to the flat plate portion of each terminal plate (32).

More specifically, each terminal plate (32) and the battery can
A compression spring (33) is interposed between the inner walls of (1), and the winding electrode body (2) is made up of a pair of compression springs (3) disposed on both sides thereof.
It is sandwiched inside the battery can (1) by the clamping pressure of 3). Incidentally, the compression spring (33) is provided in a state where the electrical insulation between the terminal plate (32) and the battery can (1) is maintained.

According to the specific structure, the wound electrode body (2) can be fixed inside the battery can (1) with a simple structure. Further, even if the wound electrode body (2) vibrates due to external vibration or impact, the compressed state of the electrode surface and the terminal plate (32) is maintained by the expansion and contraction of the compression spring (33).

[0024]

According to the secondary battery of the present invention, since the conductive strips (4) and (40) come into contact with the terminal plate (32) with a sufficient area, the electric resistance at the contact portion is reduced. As a result, high-rate discharge characteristics higher than before can be obtained.

[0025]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention applied to a lithium secondary battery will be specifically described with reference to the drawings. As shown in FIG. 1, a lithium secondary battery according to the present invention has a cylindrical aluminum battery can (1) formed by welding and fixing lids (12) and (12) to both openings of a cylindrical body (11). With both lids
(12) A pair of positive and negative electrode terminal mechanisms (3) and (3) are attached to (12). Further, a safety valve (13) is attached to each lid (12).

The wound electrode body (2) shown in FIG. 4 is housed inside the battery can (1). Winding electrode body (2)
As shown in the figure, a separator (23a), a positive electrode (21), a separator (23b) and a negative electrode (24) are stacked and spirally wound. The positive electrode (21) is formed by applying a positive electrode mixture to the surface of a belt-shaped current collector made of aluminum foil,
An uncoated portion (22) on which the positive electrode mixture is not applied is formed at one end in the winding axis direction of the current collector. The uncoated part
(22) protrudes from the separators (23a) (23b) and the negative electrode (24), and the non-coated portion (22) is cut in parallel with the winding axis direction at intervals of, for example, 6 mm to form the positive electrode ( 21) Over the entire length in the longitudinal direction, a plurality of positive conductive strips
(4) is formed.

On the other hand, the negative electrode (24) is formed by applying a negative electrode mixture to the surface of a strip-shaped current collector made of copper foil, and the non-coated portion (22) of the positive electrode (21) is formed on the current collector. ), An uncoated portion (25) is formed at one end on the opposite side. The non-coated portion (25) protrudes from the positive electrode (21) and the separators (23a) (23b), and cuts are formed in the non-coated portion (25) at intervals of, for example, 6 mm, in parallel with the winding axis direction. Thereby, a plurality of negative electrode conductive strips (40) are formed over the entire length in the longitudinal direction of the negative electrode (24).

A pair of positive and negative electrode terminal mechanisms (3) shown in FIG.
Among (3), a plurality of positive conductive strips (4) drawn from the positive electrode (21) are connected to one electrode terminal mechanism (3) serving as a positive terminal, while the negative terminal is connected. A plurality of negative conductive strips (40) drawn from the negative electrode (24) are connected to the other electrode terminal mechanism (3). This makes it possible to extract the electric power generated by the winding electrode body (2) to the outside from the pair of electrode terminal mechanisms (3) (3).

As shown in FIGS. 2 and 3, the lid (12)
A central hole (18) having a circular cross section is provided at the center, and a screw hole (15) is provided at the outer periphery. The electrode terminal mechanism (3) is provided at the center hole (18).
The safety valve (13) is screwed into the screw hole (15) after the electrolyte is injected.

Each electrode terminal mechanism (3) has a pair of insulating packings (34) and (35) having a through-hole at the center and having a convex cross section, and these insulating packings (34) and (35) are provided with a lid ( It is attached to the center hole (18) of the battery can (12) from above and below, so that electrical insulation between the lid (12) of the battery can (1) and the electrode terminal mechanism (3) is maintained, and sealing performance is improved. Is kept.

The electrode terminal mechanism (3) includes a terminal member (30) which is attached through the lid (12). The terminal member (30) on the positive electrode side is formed of aluminum, and the terminal member (30) on the negative electrode side is formed of nickel. Terminal material
(30) is a dish-shaped terminal plate (32) capable of covering the end of the wound electrode body (2), and a screw shaft (3) protruding from the terminal plate (32).
1) and the screw shaft (31) is provided with the insulating packing
(34) It passes through the central hole of (35). Then, the screw shaft (3
1) Nuts (36) from outside than the insulating packing (34)
Are screwed together to prevent the insulating packing (34) from coming off.

On the other hand, the terminal plate (32) is a winding electrode body (2).
A disk portion (32a) having an area approximately the same as the end surface of the cylindrical portion (32a), and a cylindrical portion formed on the outer peripheral portion of the disk portion (32a) and surrounding the outer peripheral surface of the end portion of the winding electrode body (2). 32b), and a plurality of electrolyte injection holes (37) are opened in the disk portion (32a).

With the wound electrode body (2) housed in the battery can (1), a plurality of positive conductive strips (4) extending from the upper end of the wound electrode body (2) are: Winding electrode body
(2) is bent from the center part to the outer periphery side, whereby a plurality of positive conductive strips (4) are wound around the electrode body.
The positive electrode surface F covering the entire upper end surface of (2) is formed. Also, a plurality of negative conductive strips extending from the lower end of the wound electrode body (2) are bent from the central part to the outer peripheral part of the wound electrode body (2). A negative electrode surface is formed so that the strip covers the entire lower end surface of the wound electrode body (2). Where the winding electrode body
As shown in FIG. 4, the positive electrode (21), the separator (23b) and the negative electrode (24) of the (2) are both end edges P1, P2 of the positive electrode (21) and the negative electrode (2).
4) Both ends N1 and N2 of the separator (23b) are both ends S
1, superposed so as to be located inside S2. Therefore, the positive conductive strip (4) is bent as described above so as not to contact the edge N1 of the negative electrode (24), and the negative conductive strip (40) is bent. There is no contact with the edge P2 of the positive electrode (21).

As shown in FIGS. 2 and 3, the terminal plate (32) is put on both ends of the wound electrode body (2), respectively. The screw shaft (31) has an insulating packing (35) and a terminal. A compression spring (33) is fitted between the plate (32). A pair of compression springs (33) (3
By the pinching force of 3), the wound electrode body (2) is pinched from both sides and fixed in the battery can (1), and each terminal plate (3
The inner surface of the disk portion (32a) of 2) is pressed against the electrode surface F, and a plurality of conductive strips (4) are connected to the electrode terminal mechanism (3). An insulating film (14) made of Teflon is formed on the entire inner peripheral surface of the cylinder (11), and the terminal plates (32) and (32) and the cylinder (1) are formed.
Electrical insulation between 1) is maintained.

During the manufacturing process of the lithium secondary battery, FIG.
In the manufacturing process of the wound electrode body (2) shown in (1), first, a positive electrode mixture is applied to the surface of a belt-shaped current collector made of aluminum foil to form a positive electrode (21). Here, a non-coated portion (22) is formed at the end in the winding axis direction of the positive electrode current collector. Then, cuts are made in the non-coated portion (22) at intervals of, for example, 6 mm in parallel with the winding axis direction, and a plurality of positive conductive strips are formed.
Form (4).

Next, a negative electrode mixture is applied to the surface of a strip-shaped current collector made of copper foil to form a negative electrode (24). Here, an uncoated portion (25) is formed at one end in the winding axis direction of the negative electrode current collector. Then, a plurality of negative conductive strips (40) are formed in the non-coated portion (25) by making cuts parallel to the winding axis direction at intervals of, for example, 6 mm. Thus, the uncoated part (22) (2
Since a plurality of cuts are made in 5) to form conductive strips (4) and (40), the bases of a plurality of current collecting tabs (8) are formed in the uncoated portions (72) and (75) as in the prior art. The work of welding the ends is unnecessary.

Thereafter, the positive electrode (21) is placed on the separator (23a).
The non-coated portion (22) separates the current collector constituting
3a), and overlap so that the edge P2 of the positive electrode (21) is located inside the edge of the separator (23a).
(21) A separator (23b) is placed on both ends S1, S2.
Are located outside the both end edges P1 and P2 of the positive electrode (21). Further, on the separator (23b), the current collector constituting the negative electrode (24) is positioned such that both edges N1, N2 of the negative electrode (24) are located inside both edges S1, S2 of the separator (23b). At the same time, the non-coated portion (25) is overlapped so as to protrude from the separator (23b), and these are spirally wound. by this,
The winding electrode body (2) is completed.

Next, as shown in FIGS. 2 and 3, a plurality of conductive strips (4) are bent to form the electrode surface F, and then the wound electrode body (2) is placed in a cylindrical body (11). ),
Terminal plate (32) of terminal member (30) on the end of winding electrode body (2)
Put on. At this time, if the terminal plate (32) is put on the end of the wound electrode body (2) so that the cylindrical portion (32b) surrounds the outermost peripheral surface of the wound electrode body (2), (32a) is the electrode surface F
Positioned accurately on top. Since the plurality of conductive strips (4) are connected to the terminal plate (32) in this manner, the tips of the plurality of current collecting tabs (8) are welded to the electrode terminal mechanism (6) as in the related art. No cumbersome work is required.

After the compression spring (33) is fitted to the screw shaft (31) of the terminal member (30), the lid (12) is put on the opening of the cylindrical body (11), and both are welded and fixed to each other. I do. Thereafter, an electrolyte is injected into the battery can (1) through the screw hole (15) of the lid (12). As a result, the electrolyte passes through the plurality of electrolyte injection holes (37) formed in the terminal plate (32) and permeates the wound electrode body (2). Finally, the safety valve (13) is screwed into the screw hole (15), and the nut (36) is further tightened to complete the assembly. As a result, the lithium secondary battery shown in FIGS. 1 and 2 is completed.

In the above-mentioned lithium secondary battery, the plurality of conductive strips (4) and (40) are in contact with the inner peripheral surface of the terminal plate (32) of the terminal member (30) with a sufficient area. The electrical resistance at the contact portion is small. In addition, since a plurality of conductive strips (4) and (40) are formed over the entire length in the edge direction of each electrode, the current collection of each electrode becomes extremely uniform. Thereby, high high-rate discharge performance can be obtained. Further, since the insulating film (14) is formed on the inner peripheral surface of the cylindrical body (11), electrical insulation between the terminal plate (32) of the terminal member (30) and the cylindrical body (11) is improved. Can be kept. Further, both ends of the wound electrode body (2) are respectively
Since it is held by the cylindrical portion (32b) of each terminal plate (32), vibration and impact are applied from the outside and the winding electrode body (2)
Even if the vibration occurs, the electrode surface F
There is no displacement with respect to (32a). Furthermore,
Since the compression spring (33) is interposed between the insulating packing (35) and the disk portion (32a) of the terminal plate (32), vibration and impact are applied from the outside, and the winding electrode body (2) is formed. Even if it vibrates,
The compressed state of the electrode surface F and each terminal plate (32) is maintained by the expansion and contraction of the compression spring (33).

[0041]

【Example】Preparation of positive electrode  Both aluminum foil (thickness 20μm) as a positive electrode current collector
The positive electrode active material (LiCoO_Two), Conductive agent (carbon powder) and
Positive electrode mixture consisting of binder (fluororesin powder)
Coating by the reed method, vacuum drying at 150 ° C for 2 hours
Then, as shown in FIG. 4, the positive electrode (21) (width 50 mm,
1500 mm). The positive electrode current collector has
An uncoated portion (22) (width 5 mm) was formed at the end.

[0042]Fabrication of negative electrode  On both sides of a copper foil (thickness 20 μm) as a negative electrode current collector,
Material (graphite powder) and binder (fluororesin powder)
Apply the electrode mixture by the doctor blade method,
Vacuum drying for 2 hours in the negative electrode (24) (width 55 mm,
(Total length 1600 mm). For the negative electrode current collector,
An uncoated portion (25) (5 mm in width) was formed at the end of.

[0043]Preparation of electrolyte  Mixed solution of ethylene carbonate and diethyl carbonate
LiPF for the medium₆Was dissolved in a solute to prepare an electrolytic solution.

[0044]Assembly of the battery of the present invention  As shown in FIG. 4, 6 mm was applied to the uncoated portion (22) of the positive electrode current collector.
Make several notches parallel to the winding axis direction at intervals
A conductive strip (4) was formed. Also, non-coating of the negative electrode current collector
Make cuts parallel to the winding axis direction at intervals of 6 mm in section (25)
Thus, a plurality of negative electrode conductive strips (40) were formed. Soshi
The separator (23a), the positive electrode (21), the separator (23b) and
The negative electrode (24) is wound in a spiral shape, as described above, and wound up.
An electrode assembly (2) was formed. The separators (23a) and (23b)
Therefore, a microporous membrane made of ion-permeable polypropylene
Using.

Then, a plurality of conductive strips (4) (4) protruding from the positive electrode (21), the negative electrode (24) and the separators (23a) (23b).
0) is bent from the center of the wound electrode body (2) to the outer peripheral side, and then the wound electrode body (2) is loaded into an aluminum cylindrical body (11) having an inner peripheral surface coated with Teflon. I do. Then, the wound electrode body covered with the positive conductive strip (4)
An aluminum terminal plate (32) is put on the upper end of (2), and a nickel terminal plate (32) is put on the lower end of the wound electrode body covered with the negative conductive strip. A compression spring (33) was fitted to (31), and both lids (12) and (12) with the insulating packings (34) and (35) were welded and fixed to the cylinder (11). Finally, inject electrolyte into the battery can (1) through the screw hole (15),
The safety valve (13) was screwed into the screw hole (15), and the nut (36) was further tightened to produce a lithium secondary battery of the present invention.

[0046]Measurement of battery characteristics  Charge / discharge experiments were performed on the following batteries under the following conditions.
No, capacity retention rate of high rate discharge to low rate discharge
Was measured. Note that the discharge capacity retention rate is lower than the low rate discharge capacity.
Is defined by the ratio (percentage) of the high rate discharge capacity. [Low-rate discharge capacity] Charge current: 400 mA, end-of-charge voltage: 4.1 V Discharge current: 400 mA, end-of-discharge voltage: 2.7 V [High-rate discharge capacity] Charge current: 400 mA, end-of-charge voltage: 4.1 V Discharge current : 5A, discharge end voltage: 2.7V

Experiment 1 In Experiment 1, a comparison was made between the high-rate discharge characteristics of the conventional battery and the high-rate discharge characteristics of the battery according to the present invention. The battery A according to the present invention has a positive electrode having a width of 50 mm, a total length of 1500 mm, a non-coated portion having a width of 5 mm, and a width of 55 mm and a total length of 160 mm.
A negative electrode having a width of 0 mm and a non-coated portion having a width of 5 mm is provided, and the non-coated portions of the positive electrode and the negative electrode are cut at intervals of 6 mm to form a plurality of conductive strips. On the other hand, a comparative battery X, which is a conventional battery, has a structure shown in FIG. 6 and has a positive electrode having a width of 50 mm and a total length of 1500 mm, and a non-coated battery having a width of 5 mm at one end in the winding axis direction. The uncoated part has an aluminum 10 mm width of 5 mm.
The current collecting tabs are welded. Further, the comparative battery X has a negative electrode having a width of 55 mm and a total length of 1600 mm, and has a non-coated portion having a width of 5 mm at one end in the winding axis direction. Ten current collecting tabs are welded. The tip portions of these current collecting tabs are welded to the electrode terminal mechanism. Table 1 shows the measurement results of these batteries A and X.

[0048]

[Table 1]

As is clear from Table 1, the battery A of the present invention
Has a higher discharge capacity retention ratio than the comparative battery X, and has good high-rate discharge characteristics. This is because the plurality of conductive strips come into contact with the terminal plate with a sufficient area to reduce the electric resistance at the contact portion, and the plurality of conductive strips extend over the entire length in the edge direction of the electrode. It is considered that the current collecting property was extremely uniform due to the formation, and the high rate discharge capacity was increased.

Experiment 2 In Experiment 2, the optimum range of the cut interval in the conductive strip forming step of the secondary battery of the present invention was examined. The winding electrode body shown in FIG.
The cut interval for the circumference of the air core (20) in (2) is 0.09.
Battery B of the present invention in the same manner as Battery A of the present invention, except that
0 was produced. The battery B1 of the present invention was prepared in the same manner as the battery A of the present invention, except that the cut interval was 3 mm and the cut interval with respect to the circumferential length of the air core (20) of the wound electrode body (2) was 0.14. did. A battery B2 of the present invention was prepared in the same manner as the battery A of the present invention, except that the cut interval was 7 mm and the cut interval with respect to the circumferential length of the air core (20) of the wound electrode body (2) was 0.32. did. A battery B3 of the present invention was produced in the same manner as the battery A of the present invention, except that the cut interval was 10 mm and the cut interval with respect to the circumferential length of the air core (20) of the wound electrode body (2) was 0.45. did. Table 2 shows the measurement results of these batteries B0 to B3 and A of the present invention.

[0051]

[Table 2]

As is evident from the results in Table 2, the cut interval with respect to the circumferential length of the air core (20) of the winding electrode body (2) is equal to 0.
When it is 32 or less, the discharge capacity retention ratio is as high as 85% or more. This is because when the cut interval with respect to the circumferential length of the air core (20) of the winding electrode body (2) is reduced, the conductive strip (4) is moved along the end face of the winding electrode body (2). It can be considered that the contact area between the terminal strip (32) of the terminal member (30) and the conductive strip (4) increases.

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, in the present embodiment,
As shown in FIG. 4, the conductive strips (4) and (40) are formed by making cuts in the uncoated portions (22) and (25) of the electrodes (21) and (24).
As shown in FIG. 5, the metal foils (56) and (57) are cut in advance to form conductive strips (41) and (42), and the metal foils (56) and (57) are not coated with a current collector. It is also possible to adopt a configuration of welding and fixing to the working sections (52) and (55). In this case, the uncoated portion of the current collector (52) (5
In 5), since the metal foils (56) and (57) are stacked to increase the mechanical strength, breakage during winding is prevented, and the yield of the manufacturing process is improved.

[Brief description of the drawings]

FIG. 1 is a perspective view illustrating an appearance of a cylindrical lithium secondary battery according to an embodiment.

FIG. 2 is a cross-sectional view illustrating a main part of the cylindrical lithium secondary battery.

FIG. 3 is an exploded perspective view of an electrode terminal mechanism.

FIG. 4 is an exploded perspective view showing a part of a wound electrode body for explaining a configuration of a conductive strip of the present embodiment.

FIG. 5 is an exploded perspective view showing a part of a wound electrode body for explaining a configuration of a conductive strip according to another embodiment.

FIG. 6 is a perspective view illustrating a main part of a conventional cylindrical lithium secondary battery.

FIG. 7 is an exploded perspective view showing a part of a wound electrode body for explaining a configuration of a conventional current collecting tab.

FIG. 8 is an exploded perspective view showing a part of a wound electrode body for explaining a configuration of another current collecting tab.

[Explanation of symbols]

 (1) Battery can (11) Cylindrical body (12) Lid (2) Winding electrode body (3) Electrode terminal mechanism (31) Screw shaft (32) Terminal plate (33) Compression spring (34) Insulation packing ( 35) Insulation packing (36) Nut

Continued on the front page (72) Inventor Takeshi Maeda 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Inside Sanyo Electric Co., Ltd. (72) Inventor Atsuhiro Funabashi 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Inside Sanyo Electric Co., Ltd. (72) Inventor Toshiyuki Noma 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Prefecture Inside Sanyo Electric Co., Ltd. (72) Inventor Ikuo Yonezu 2-chome, Keihanhondori, Moriguchi-shi, Osaka No. 5 Sanyo Electric Co., Ltd. F term (reference) 5H022 AA09 AA18 BB01 BB02 BB03 CC03 CC08 CC12 CC13 CC21 KK03

Claims (7)

[Claims] 1. A chargeable / dischargeable winding electrode body (2) is accommodated in a battery can (1) to which an electrode terminal mechanism (3) is attached, and each of the winding electrode bodies (2) has a belt-like shape. Positive electrode (2
1) and the negative electrode (24) are spirally wound with a separator (23b) interposed between the two electrodes. The wound electrode body (2) and the electrode terminal mechanism (3) are electrically connected to each other. Thus, in a secondary battery in which the electric power generated by the winding electrode body (2) can be taken out from the electrode terminal mechanism (3), at least one of the positive electrode (21) and the negative electrode (24) is used. A plurality of conductive strips (4) and (40) protrude from the end in the winding axis direction, and the plurality of conductive strips (4) and (40) are provided at the edge of the electrode or the separator. The edge of (23b) is bent along the exposed end surface of the wound electrode body to form an electrode surface F covering substantially the entire end surface, and the electrode terminal mechanism (3) is provided inside the battery can (1). And a terminal plate (32) to be crimped on the electrode surface F. 2. An electrode, on which a plurality of conductive strips (4), (40) are protruded, comprises a strip-shaped current collector, and the current collector is provided with a coating portion coated with an electrode material. Are formed, and uncoated portions (22) and (25) on which the electrode material is not applied are formed at one end in the winding axis direction, and the uncoated portions (22) and (25) are wound around the uncoated portions (22) and (25). By making multiple cuts along the axial direction,
A plurality of conductive strips (4) (40) over the entire length of the electrode edge
The secondary battery according to claim 1, wherein the secondary battery is formed. 3. An electrode, on which a plurality of conductive strips (41), (42) are protruded, comprises a strip-shaped current collector, and the current collector is coated with an electrode material. Is formed, and an uncoated portion (52) (55) where the electrode material is not applied is formed at one end in the winding axis direction, and a strip-shaped portion is formed on the non-coated portion (52) (55). The ends of the metal foils (56) and (57) are connected, and the metal foils (56) and (57) are connected.
By making a plurality of cuts in the direction along the winding axis direction of the wound electrode body (5), a plurality of conductive strips (41) and (42) are formed over the entire length of the electrode edge. The secondary battery according to claim 1. 4. An insulating film is provided on the inner peripheral surface of the battery can (1) at least in a region surrounding the terminal plate (32) of the electrode terminal mechanism (3).
The secondary battery according to any one of claims 1 to 3, wherein (14) is formed. 5. A winding electrode body (2) is housed inside a battery can (1) having a pair of electrode terminal mechanisms (3) (3) fixed at both ends, and the winding electrode body (2). Is a strip-shaped positive electrode
(21) and a negative electrode (24) are spirally wound with a separator (23b) interposed between the two electrodes. The winding electrode body (2) and each electrode terminal mechanism (3) are electrically connected to each other. The power generated by the wound electrode body (2) is connected to a pair of electrode terminal mechanisms.
(3) In the secondary battery which can be taken out from (3), a plurality of positive conductive strips (4) are protruded from one end of the positive electrode (21) in the winding axis direction. A plurality of negative conductive strips (40) are protruded from the other end of the negative electrode (24) in the winding axis direction, and the plurality of positive conductive strips (4) are connected to the end of the positive electrode (21). While the edge or the edge of the separator (23b) is bent along one end face of the wound electrode body (2) where the negative electrode is covered to cover substantially the entire area of the end face, a plurality of negative electrode conductors are formed. The flexible strip (40) is bent along the other end face of the wound electrode body (2) where the edge of the negative electrode (24) or the edge of the separator (23b) is exposed, and covers substantially the entire area of the end face. A covering negative electrode surface is formed, and a pair of electrode terminal mechanisms (3) and (3)
At the end protruding into the battery can (1), there are provided a pair of positive and negative terminal plates (32) (32) which are crimped to the two electrode surfaces, and the winding electrode body (2) is provided with a pair of the two electrode surfaces. A secondary battery characterized in that the terminal plates (32) and (32) are clamped from both sides by crimping. 6. Each of the terminal plates (32) has a flat plate portion formed with a crimping surface engageable with the electrode surface, and is formed on an outer peripheral portion of the flat plate portion, and at least an end portion of the winding electrode body. 6. The secondary battery according to claim 5, comprising a cylindrical portion surrounding the outermost peripheral surface. 7. A compression spring (33) is interposed between each terminal plate (32) and the inner wall of the battery can (1), and the winding electrode body (2) is
The rechargeable battery according to claim 5, wherein the rechargeable battery is held inside the battery can by a pressing force of a pair of compression springs disposed on both sides thereof.