JP2002042771A - Secondary battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a secondary battery having output characteristics not to be deteriorated and excellent in vibration resistance even if vibration or impact is applied from the outside, in a secondary battery having a wound electrode body housed in a battery can and capable of taking out electric power generated by the wound electrode body from an electrode terminal mechanism attached to the battery can to the outside. SOLUTION: In this secondary battery, the end edge of a positive electrode or a negative electrode is projected on at least one end of a wound electrode body 2, and a collecting plate 33 is joined to the end edge. The collecting plate 33 is connected to the base end of an electrode terminal mechanism 40 through a spiral elastic support lead 3, the wound electrode body 2 is elastically supported by the elastic support lead 3 in a battery can 1, and the wound electrode body 2 is electrically connected to the electrode terminal mechanism 40.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a secondary battery capable of extracting electric power generated by an electrode body housed in a battery can from an electrode terminal mechanism attached to the battery can to the outside. The present invention relates to a secondary battery having high durability against shock and impact.

[0002]

2. Description of the Related Art In recent years, while air pollution by exhaust gas from automobiles and the like has become a worldwide problem, electric vehicles using electricity as a power source of the automobile have been receiving attention. A cylindrical lithium secondary battery is being developed as a power source.

In a conventional cylindrical lithium secondary battery, as shown in FIG. 5, a battery can (1) is formed by fixing lids (12) and (12) to both ends of a cylindrical body (11). The wound electrode body (2) is housed inside the battery can (1). Winding electrode body
Current collecting plates (34) are provided at both ends of (2), respectively, and are laser-welded to the ends of the wound electrode body (2). or,
Each current collecting plate (34) is connected to an electrode terminal mechanism (4) attached to the lid (12) via a current collecting lead (35).

[0004] As shown in FIG.
Each of the strip-shaped positive electrode (23), separator (22), and negative electrode (2
It consists of 1). The positive electrode (23) is formed by applying a positive electrode active material (26) made of LiCoO _{2 on} the surface of a core made of aluminum foil, and the negative electrode (21) is made of natural graphite on the surface of a core made of copper foil. The negative electrode active material (24) is applied. The positive electrode (23) and the negative electrode (21) are each a separator
(22) It is superimposed on the upper part while being shifted in the width direction, and is wound in a spiral shape. Thereby, the winding electrode body (2)
At one of the two axial ends, the edge of the spirally wound negative electrode (21) (the uncoated portion (25)) is more outward than the edge of the separator (22). At the other end, the spirally wound edge of the positive electrode (23) (the uncoated portion (27)) projects outward beyond the edge of the separator (22). Will do. For example, the active material coating section of each electrode (24) (26)
Width A is several tens of mm, and width B of the uncoated portions (25) and (27) is 10 mm.
And the protrusion distance S from the separator (22) can be formed to be about 1 to 3 mm.

As shown in FIG. 5, the electrode terminal mechanism (4) is a terminal member having a flange (43) projecting from the lower end of a screw shaft (42).
(41). The screw shaft portion (42) of the terminal member (41) penetrates the lid (12), and a first insulating member (45) and a second insulating member (46) are attached around the terminal member (41). Thus, electrical insulation and airtightness between the lid (16) and the terminal member (41) are maintained. Further, a washer (47) is fitted to the tip of the terminal member (41), and a nut (48) is screwed into the terminal member (41). The tip of the current collecting lead (35) extending from the current collecting plate (34) is connected to the electrode terminal mechanism (4).
Is welded to the flange portion (43) of the terminal member (41). As a result, the electric power generated by the winding electrode body (2) can be taken out from the pair of positive and negative electrode terminal mechanisms (4) (4).

In a cylindrical lithium secondary battery used as a power source for an electric vehicle, vibrations and shocks are repeatedly applied to the battery as the electric vehicle travels. It may move violently inside (1), causing clogging of the separator (22) or peeling of the electrode active material from the positive electrode (23) and the negative electrode (21), which may increase the internal resistance of the battery. Was.

Therefore, there is a demand for the development of a cylindrical lithium secondary battery having high durability against vibration and impact. For example, in the secondary battery shown in FIG. 7 (Japanese Patent Application Laid-Open No. Hei 10-92469), a winding core (9) is fixed to the center of a winding electrode body (2) and attached to an end of the winding core (9). A coil spring (92) is interposed between the cap (91) and the can lid (16), and the coil core (9) is elastically supported by the coil spring (92). In the secondary battery, even if vibration or impact is applied to the battery and an exciting force acts on the winding electrode body (2), the coil spring (92) exhibits a vibration suppressing effect, and the winding electrode body
The vigorous movement of (2) is suppressed.

[0008]

However, in the secondary battery shown in FIG. 7, it is the winding core (9) that is directly elastically supported by the coil spring (92). The winding electrode body (2) is connected to the winding electrode body (9), especially in a situation where sudden vibration is repeatedly applied, such as when mounted on an electric vehicle.
(2) may be displaced in the axial direction.
1) There has been a problem that wrinkles and the like are generated in the positive electrode (23) or the separator (22), and the output characteristics are deteriorated.

[0009] Therefore, an object of the present invention is to prevent the output characteristics from deteriorating even when external vibration or shock is applied.
An object of the present invention is to provide a secondary battery having excellent vibration resistance.

[0010]

In a secondary battery according to the present invention, an electrode body in which a separator (22) is interposed between a positive electrode (23) and a negative electrode (21) in a battery can (1). (2) is contained,
The electric power generated by the electrode body (2) can be taken out from the electrode terminal mechanism (40) attached to the battery can (1). Here, the edge of the positive electrode (23) or the negative electrode (21) protrudes from at least one end of the electrode body (2), and the current collector plate (33) is joined to the edge, and the current collector plate (33) is an elastic support lead
The electrode body (2) is connected to the base end of the electrode terminal mechanism (40) via (3), and the electrode body (2) is connected to the battery can by an elastic support lead (3).
The electrode body (2) is elastically supported in (1), and is electrically connected to the electrode terminal mechanism (40).

In the above secondary battery of the present invention, the electrode body
The current collector plate (33) joined to the end of (2)
Since it is elastically supported by (3), the negative electrode (21), the separator (22) and the positive electrode (23) constituting the electrode body (2) are collected even if severe vibration or impact is applied from the outside. Electric board
It is received by (33) and does not deviate from each other.
Therefore, there is no possibility that the negative electrode (21), the positive electrode (23), and the separator (22) may be wrinkled, thereby preventing the output characteristics from deteriorating. In addition, since the current collecting plate (33) is electrically connected to the electrode terminal mechanism (40), the conventional current collecting lead is unnecessary, and the number of components can be reduced.

In a specific configuration, the elastic support lead (3)
Is formed by spirally shaping a metal strip. According to this specific configuration, even if the elastic modulus of the metal itself forming the elastic support lead (3) is small, the spring constant of the elastic support lead (3) increases, and the elastic support lead (3) is sufficiently Exhibits a great vibration suppression effect.

More specifically, the base end portion (31) of the elastic support lead (3) is formed in a ring shape that makes substantially one round along the surface of the current collector plate (33). ) Is fixed to the surface. Therefore, the vibration suppressing force accompanying the elastic deformation of the elastic support lead (3) acts without bias on the current collector (33).
As a result, rocking of the electrode body (2) in the battery can (1) is prevented.

Furthermore, the tip (32) of the elastic support lead (3)
Is held at the base end of the electrode terminal mechanism (40). Therefore, the tip (32) of the elastic support lead (3) is connected to the electrode terminal mechanism (4).
It is not necessary to apply welding to connect to the base end of 0),
Connection can be performed with simple operations. Of course, it is possible to increase the joint area between the tip portion (32) of the elastic support lead (3) and the electrode terminal mechanism (40), thereby reducing the contact resistance and obtaining high output characteristics. I can do it.

[0015]

According to the secondary battery of the present invention, even if vibration or impact is applied from the outside, the elastic supporting lead effectively suppresses the vibration, so that excellent vibration resistance can be obtained.
Deterioration of output characteristics is prevented.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention applied to a cylindrical lithium secondary battery will be specifically described below with reference to the drawings. In the cylindrical lithium secondary battery according to the present invention, as shown in FIG. 1, a lid (12) is attached to each open end of the cylindrical body (11).
Is fixed by welding to form a cylindrical battery can (1), the wound electrode body (2) is housed inside the battery can (1), and the electric power generated by the wound electrode body (2) Can be taken out from the pair of positive and negative electrode terminal mechanisms (40) (40) attached to the lids (12) (12). Further, a gas discharge valve (13) is attached to each lid (12), so that when the internal pressure of the battery can (1) increases, gas can be discharged to the outside.

The winding electrode body (2) is, as shown in FIG.
A band-shaped separator (22) is interposed between the band-shaped positive electrode (23) and the band-shaped negative electrode (21), and these are wound up in a spiral. The positive electrode (23) is formed by applying a positive electrode active material (26) made of a lithium composite oxide to both surfaces of a band-shaped core made of aluminum foil, and the negative electrode (21) is made of both surfaces of a band-shaped core made of copper foil. A negative electrode active material (24) containing a carbon material is applied to the substrate. The non-aqueous electrolyte is impregnated in the separator (22).

The positive electrode (23) has a coated portion on which the positive electrode active material (26) is applied and a non-coated portion (27) on which the positive electrode active material is not applied. The negative electrode (21) has a coated portion on which the negative electrode active material (24) is applied and a non-coated portion (25) on which the negative electrode active material is not applied. Positive electrode (2
3) and the negative electrode (21) are overlapped with each other on the separator (22) while being shifted in the width direction, and the uncoated portions (27) and (25) of the positive electrode (23) and the negative electrode (21) are separated from the separator (22). Project outward from both edges. Then, these are spirally wound to form a wound electrode body (2). In the wound electrode body (2), at one end of both ends in the winding axis direction, the uncoated portion (27) of the positive electrode (23) is larger than one end of the separator (22). At the other end, the uncoated portion (25) of the negative electrode (21) projects outward from the other end of the separator (22).

Current collecting plates (33) are provided at both ends of the wound electrode body (2), and are laser-welded to the edges of the core body. The current collector plate (33) has a plurality of liquid injection holes (33a). An elastic support lead (3) is fixed to the surface of the current collector (33). As shown in FIG. 3, the elastic support lead (3) is formed by spirally forming a metal strip, and its base end (31) extends along the surface of the current collector (33). And a central hole (32a) is formed in the tip (32).
The current collector plate (33) and the elastic support lead (3) on the positive electrode side are made of aluminum, and the current collector plate (33) and the elastic support lead (3) on the negative electrode side are made of copper, and the surface thereof is plated with nickel. Is given. Here, the elastic modulus of aluminum is 6300
７7500 Kg / mm ² , and the elastic modulus of copper is 700
Although it is 0 to 10000 kg / mm ² , a spring constant large enough to elastically support the wound electrode body can be obtained by forming a strip made of these materials into a spiral shape.

As shown in FIG. 1, the electrode terminal mechanism (40) includes a fastening member (7) inserted into a central through hole of the lid (12).
Electrical insulation and sealing are provided between the central through hole of the lid (12) and the fastening member (7) by a pair of insulating packings (8) and (81). The fastening member (7) integrally includes a screw portion (71) protruding outside the lid (12) and integrally includes a flange portion (72) protruding inside the lid (12). . Lid (12)
A large-diameter O-ring (8
2), and a small-diameter O-ring (83) is interposed between the insulating packing (8) and the facing surface of the flange portion (72) of the fastening member (7). The first fastening nut (7) is attached to the screw portion (71) of the fastening member (7) projecting to the outside of the lid (12) via a washer (61).
3) and the second fastening nut (74) are screwed together.

A pressing member (5) is inserted through a central hole (75) of the fastening member (7) from the inside of the lid (12). The clamping member (5) includes a shaft (50) penetrating the fastening member (7), and a distal end of the shaft (50) extends from the fastening member (7) to the outside of the lid (12). A projecting screw portion (53) is formed. On the other hand, the shaft
A circular pressure plate (51) is fixed to the base end of (50). A circular pressure receiving plate is provided on the shaft portion (50) of the pressing member (5).
(6) is loosely fitted. Flange part (72) of fastening member (7)
And a small-diameter O-ring (84) between the opposing surfaces of the pressure receiving plate (6).
Is interposed. The shaft portion (50) of the clamping member (5) passes through the central hole (75) of the clamping receiving plate (6) and the fastening member (7), and the screw portion ( 53) and a pinching nut (5
4) is screwed. The distal end portion (32) of the elastic support lead (3) fixed to the current collector plate (33) has a through hole through which the shaft portion of the pressing member (5) extends.
(50), and sandwiched between the pressure plate (51) of the pressure member (5) and the pressure receiving plate (6), and connected to the electrode terminal mechanism (40).

In the manufacturing process of the cylindrical lithium secondary battery according to the present invention, the wound electrode body (2) shown in FIG. 2 is manufactured, while the outer surfaces of the pair of positive and negative current collectors (33) and (33) are formed. The base end (31) of each elastic support lead (3) is fixed by welding. Then, the inner surfaces of the pair of positive and negative current collecting plates (33) and (33) are joined to both ends of the wound electrode body (2) by laser welding. Thereafter, as shown in FIG. 1, the wound electrode body (2) is housed inside the tubular body (11) of the battery can (1). Also, each elastic support lead
Insert the tip (32) of (3) into the pressure receiving plate (6) of the electrode terminal mechanism (40).
And the pressure plate (51), and the electrode terminal mechanism (40) is
(12), and the lid (12) is laser-welded to the opening of the cylindrical body (11). Finally, after the electrolyte is injected into the battery can (1), the gas discharge valve (13) is screwed and fixed to the lid (12) to complete the cylindrical lithium secondary battery of the present invention.

In the cylindrical lithium secondary battery of the present invention, both current collectors (33) (33) joined to both ends of the wound electrode body (2) have elastic support leads (3) (3) from both sides. 3), the negative electrode (21), the separator (22), and the positive electrode (23) constituting the winding electrode body (2) are not affected even when a strong vibration or shock is applied from outside. Current collector (3
It is received by 3) and does not shift from each other. Therefore, there is no possibility that the negative electrode (21), the positive electrode (23), and the separator (22) may be wrinkled, thereby preventing the output characteristics from deteriorating.

[0024]

EXAMPLE Through the following steps, a cylindrical lithium secondary battery of the present invention shown in FIGS. 1 to 3 and a conventional cylindrical lithium secondary battery shown in FIG. 7 were prototyped. A test was performed to examine changes in power density.

[0025]Preparation of positive electrode  LiCoO as a positive electrode active material₂of
Weight ratio of powder (average particle size 5μm) and artificial graphite as conductive agent
The mixture was mixed at 9: 1 to produce a positive electrode mixture. Next, with a binder
Certain polyvinylidene fluoride (PVdF) is converted to N-methyl-2.
-Prepare NMP solution by dissolving in pyrrolidone (NMP)
did. Then, the weight of the positive electrode mixture and polyvinylidene fluoride
The positive electrode mixture and the NMP solution are kneaded so that the ratio becomes 95: 5.
Thus, a slurry was prepared. This slurry is used as a positive electrode current collector.
Doctor on both sides of aluminum foil (thickness 20μm)
Coating by blade method, vacuum drying at 150 ° C for 2 hours
To obtain a positive electrode. However, as shown in FIG.
An uncoated portion (27) is formed at one end of 3).

[0026]Fabrication of negative electrode  Empty in carbon lump (d002 = 3.356Å; Lc> 1000)
An air stream was injected and pulverized to produce a carbon powder. Also, binding
Dissolving polyvinylidene fluoride as an agent in NMP
Prepare MP solution and mix carbon powder and polyvinylidene fluoride
The carbon powder and the NMP solution were mixed so that the weight ratio became 85:15.
The slurry was prepared by kneading. This slurry is
Doctor shake on both sides of copper foil (20μm thick)
And dried under vacuum at 150 ° C for 2 hours.
Thus, a negative electrode was obtained. However, as shown in FIG.
An uncoated portion (25) is formed at one end.

[0027]Preparation of electrolyte  Volume of ethylene carbonate and diethyl carbonate
LiPF was added to the solvent mixed at a ratio of 1: 1.₆At a rate of 1 mol / l
And dissolved to prepare an electrolytic solution.

[0028]Assembly of the battery of the present invention  Permeation of ion into separator of 10mm diameter
After winding the porous microporous membrane several times,
Separator, so that the separator is interposed between the positive and negative electrodes,
A positive electrode, a separator and a negative electrode are superposed on each other.
Is wound in a spiral, and finally the core is pulled out.
A scraped electrode body was produced. Next, both ends of the wound electrode body
A current collector was laser bonded to the end. And the winding power
The polar body is loaded inside the cylinder and fixed to each current collector
After connecting the tip of the elastic support lead to the electrode terminal mechanism,
The lid was laser welded to the opening of the cylinder. Note that the elastic support
The thickness of the strip forming the cord was 0.6 mm. Most
Later, the electrolyte was injected into the battery can, and the diameter was 57 mm and the length was 57 mm.
The battery 1 of the present invention having a length of 220 mm was assembled. In addition, winding
The weight of the electrode body was 920 g.

[0029]Production of Comparative Example Battery A  Permeation of ion into separator of 10mm diameter
After winding the porous microporous membrane several times,
Separator, so that the separator is interposed between the positive and negative electrodes,
A positive electrode, a separator and a negative electrode are superposed on each other.
Winding electrode with a winding core
The body was made. Next, both ends of the winding core of the winding electrode body
Place the cap and coil spring in the
The front end of the cable is joined to the back of the lid, as shown in FIG.
Comparative Example Battery A was prepared.

[0030]Battery evaluation  A vibration test was performed on the battery of the present invention and the battery of the comparative example.
Was. In the vibration test, the amplitude was 1 mm, and the sweep speed was 1H.
At z / min, reduce the frequency from 10 Hz to 55 Hz
While making various changes, 1 is set in the three XYZ directions orthogonal to each other.
Vibration was applied for 00 minutes. And before and after the vibration test
Output characteristics (DOD 50%, output density during 15 seconds discharge)
Was asked for a change. Table 1 shows the results.

[0031]

[Table 1]

As is apparent from Table 1, in the battery 1 of the present invention in which the current collector plate is elastically supported by the spiral elastic support leads, the output density is lower than in the comparative example battery in which the winding core is elastically supported by the coil spring. Is kept small. This is because the impact applied to the wound electrode body cannot be sufficiently absorbed only by elastically supporting the winding core by the coil spring as in the battery A of the comparative example, whereas the helical elasticity as in the battery 1 of the present invention cannot be absorbed. By elastically supporting the current collector with the support leads, the entire area of both end surfaces of the positive electrode and the negative electrode of the winding electrode body can be pressed, thereby preventing the positive electrode, the separator, and the negative electrode from shifting, It is considered that the occurrence of wrinkles was suppressed.

[0033]Study on the thickness of the elastic support lead (3)  In the battery 1 of the present invention, the elastic support lead (3) is formed.
Change the thickness of the strip that is
Prototypes of the ten types of batteries of the present invention 2-1 to 2-10,
The change in the power density was examined in the same manner as described above. as a result
Are shown in Table 2.

[0034]

[Table 2]

As is evident from Table 2, the output density is suppressed to less than 20 W / Kg when the thickness of the strip of the elastic support lead is in the range of 0.1 mm to 2.0 mm. Then, the decrease in the output density is as large as 20 W / Kg or more. This means that if the plate thickness is less than 0.1 mm,
When the spring constant of the elastic support lead becomes excessively small and sufficient shock absorbing ability cannot be obtained, wrinkles are generated in the separator and the electrode, and when the plate thickness is larger than 2.0 mm, the rigidity of the elastic support lead becomes large. This is thought to be due to the fact that the elastic deformation becomes difficult due to an excessively large amount, and it becomes impossible to effectively absorb vibrations and shocks. Therefore, wrinkles are generated in the electrodes and the internal resistance of the battery is increased.

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 shape of the elastic support lead (3) is not limited to a spiral shape, and the same effect can be obtained even if the elastic support lead (3) has a bellows portion (36) as shown in FIG.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a main part of a cylindrical lithium secondary battery according to the present invention.

FIG. 2 is an exploded perspective view of a winding electrode body, a current collector, and an elastic support lead.

FIG. 3 is an enlarged perspective view of an elastic support lead.

FIG. 4 is a sectional view showing another configuration example of the elastic support lead.

FIG. 5 is a partially cutaway front view showing a conventional cylindrical lithium secondary battery.

FIG. 6 is a partially developed perspective view of a wound electrode body.

FIG. 7 is a cross-sectional view showing a main part of another conventional cylindrical lithium secondary battery.

[Explanation of symbols]

 (1) Battery can (11) Cylindrical body (12) Lid (2) Winding electrode body (33) Current collector plate (3) Elastic support lead (31) Base end (32) Tip (40) Electrode terminal Mechanism (5) Pressing member (51) Pressing plate (6) Pressing receiving plate (7) Fastening member

Continued on the front page (72) Inventor Toshiyuki Noma 2-5-5 Keihanhondori, Moriguchi-shi, Osaka Inside Sanyo Electric Co., Ltd. (72) Inventor Ikuro Yonezu 2-5-5-1 Keihanhondori, Moriguchi-shi, Osaka No. Sanyo Electric Co., Ltd. F-term (reference) 5H022 AA09 CC02 CC12 CC16 EE09

Claims (4)

[Claims] An electrode body (2) having a separator (22) interposed between a positive electrode (23) and a negative electrode (21) is accommodated in a battery can (1). In a secondary battery capable of taking out generated electric power from an electrode terminal mechanism (40) attached to a battery can (1), a positive electrode (23) is attached to at least one end of the electrode body (2). Alternatively, the edge of the negative electrode (21) protrudes, a current collector (33) is joined to the edge, and the current collector (33) is
It is connected to the base end of the electrode terminal mechanism (40) via the elastic support lead (3), and the electrode body (2) is elastically supported in the battery can (1) by the elastic support lead (3). Together with the electrode body
A secondary battery wherein (2) is electrically connected to an electrode terminal mechanism (40). 2. The secondary battery according to claim 1, wherein the elastic support lead is formed by spirally forming a metal strip. 3. A base end (31) of the elastic support lead (3) is formed in a ring shape substantially making a round along the surface of the current collector (33), and is formed on the surface of the current collector (33). The secondary battery according to claim 2, which is fixed. 4. The secondary battery according to claim 1, wherein the distal end portion (32) of the elastic support lead (3) is held between the base end portion of the electrode terminal mechanism (40). .