JP2001102032A - Electric cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent breakdown in a pleat line of a connection member. SOLUTION: In the electric cell has a planar connecting member for electrically connecting electrodes inserted within a cell housing with a terminal portion mounted on the cell housing and the electrodes are formed as a wound body wound with a separator, the electrical cell has a bending portion formed by working the connecting member in a linear discontinuous crimping manner.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a battery resistant to vibration and impact.

[0002]

2. Description of the Related Art For example, a cylindrical lithium battery is a wound body having a structure in which a positive electrode and a negative electrode are wound multiple times around a cylindrical core having electrolytic solution resistance via a separator. As a power generating element, a plate-like connecting member is connected to the electrodes constituting the power generating element, and this is connected to a terminal portion provided on the battery container so that current is taken out of the battery. It has a simple structure.

The connecting member must be efficiently housed in the space between the power generating element and the battery top plate in order to reduce the size and weight of the battery. In many cases, a bent portion is provided to effectively use a limited space. In this case, in many cases, the bent portion has been subjected to a linear fold processing in advance for the purpose of simplifying the bending process and accurately bending the connecting member at a predetermined portion.
For example, a linear mark is formed by press working over the entire width of the bent portion, or a straight shaving is performed.

[0004]

Applying the fold processing as described above is very effective in that it simplifies the bending process and allows the connecting member to be accurately bent at a predetermined portion. Means. However, the size of conventional lithium batteries was relatively small.However, when these batteries became larger and were used in applications that often suffered from shock and vibration, such as for automobiles, the batteries became subject to shock and vibration. This has caused a problem that the current collecting member is damaged by the fold.

[0005] It is an object of the present invention to prevent such breakage of the connecting member at the fold.

[0006]

SUMMARY OF THE INVENTION According to the present invention, a discontinuous fold is formed in a bent portion so that an unfolded portion is present in the fold, and strength is imparted to the unfolded portion. To improve the strength of the fold. That is, the battery of the present invention is a battery provided with a plate-shaped connecting member for electrically connecting the terminal portion and the electrode, wherein the connecting member has a bent portion, and the bent portion has a straight non-linear shape. It is characterized by continuous crease processing.

In particular, in the case of a battery in which the electrodes are housed inside the battery container as a wound body with a separator interposed therebetween, since the load of the whole wound body is applied to the current collecting member, each electrode is separately provided. The load on the bent portion is greater than that of a stack-type battery connected by a current collecting member, and the application of the battery structure of the present invention is effective.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The preferred embodiments of the present invention will be described below, and the present invention will be further described below.

The battery of the present invention is, for example, one in which a metal battery case is provided with a terminal portion, and a wound body in which electrodes are wound via a separator is placed inside the battery case. The terminal portion is a portion connected to the positive terminal or the negative terminal provided on the battery container. And the connection member is
The terminal portion and the electrode are electrically connected, and are connected to the terminal portion and the electrode by, for example, welding.

[0010] The connecting member has at least one bent portion, and a linear discontinuous fold process is performed on the bent portion in advance. For example, the fold process is performed by pressing a fold portion by pressing. It can be performed by forming engraved marks arranged linearly at intervals, forming grooves formed by shaving at linear intervals, or punching out a plurality of openings linearly. In this way, the fold processing can be performed, for example, by making the thickness thinner than the peripheral portion, and it is only necessary that this portion bend more easily than the peripheral portion.

[0011] By applying the linear discontinuous fold processing to the bent portion in this manner, simple bending at a predetermined position of the connecting member can be performed, and appropriate strength against vibration and impact can be maintained. Becomes possible. This makes it possible to improve the reliability of the battery.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in more detail based on more preferred embodiments. The present embodiment is directed to a non-aqueous electrolyte battery in which a negative electrode made of a substance capable of inserting and extracting lithium ions suitable for the present invention, a positive electrode, and an electrode group (wound body) formed by winding a separator are housed in a battery case. And a negative electrode having a mixture layer containing a carbon material capable of occluding and releasing lithium ions and a binder, in which the application of the present invention is more effective, and a composite oxidation of lithium and a transition metal. The present invention provides an organic electrolyte secondary battery including an electrode group having a structure in which a positive electrode having a positive electrode mixture layer containing the active material, a conductive agent, and a binder is used as an active material and a separator is interposed therebetween.

Example 1 0.5 mol of lithium carbonate and 1 mol of cobalt carbonate were mixed as a positive electrode active material,
Calcination in air at ℃ gave LiCoO2. This Li
91% by weight of CoO2 and 6 of graphite as a conductive agent
Wt% and polyvinylidene fluoride (PVD) as a binder
F) 3% by weight was mixed to prepare a positive electrode mixture. N-methyl-2-pyrrolidone was added as a solvent to this positive electrode mixture, mixed and dispersed to form a slurry. Thickness of 20 as an electrode substrate (1)
Using a strip-shaped aluminum foil of μm, the cathode mixture slurry was uniformly applied to the substrate (1), and dried, and then the thickness was adjusted using a roll press to prepare a strip-shaped cathode (2). 10 mm on one edge of the long side of this electrode
An uncoated portion (3) having a width of is provided. (See Figure 1: Plan view of positive electrode structure)

For the negative electrode (5), a carbon material (graphite) powder capable of doping / dedoping lithium was used.
90% by weight of graphite powder, PVD as binder
F was mixed at 10% by weight to prepare a negative electrode mixture. N-methyl-2-pyrrolidone was added as a solvent to this negative electrode mixture, and kneaded to form a slurry. 20 μm thick as electrode substrate (4)
m, a negative electrode mixture slurry was uniformly applied to the substrate (4), dried, and then adjusted in thickness using a roll press to prepare a band-shaped negative electrode (5). Similarly to the positive electrode (2), 10 mm
An uncoated portion (6) having a width of 5 mm was provided. (See Figure 2: Plan view of negative electrode structure)

The positive electrode (2) and the negative electrode (5) thus produced are sandwiched between a separator (7) composed of a microporous polyethylene film and a core (8) composed of a polyimide pipe.
And a power generating element was obtained. At this time, as shown in the schematic perspective view of the power generating element in FIG. 3, the edges of the electrodes (positive electrode, negative electrode) with the bases (1, 4) exposed are made to protrude from the edge of the other electrode. Wound.

Next, the outer peripheral portion of the cylindrical power generating element is fixed with a tape (9) and crushed to form a power generating element having an oval cross section as shown in a schematic perspective view of a wound body of FIG. did. As shown in a schematic perspective view of a wound body in which the connecting member of FIG. 5 is arranged with the same material as that of the base body (1) on the straight portions at the upper and lower edges of the power generating element, a crease process is performed on both edges. A positive electrode current collector (10), which is a connecting member having the same, and a negative electrode current collector (11), which is a connecting member having creases formed on both end edges in the same manner, are mounted, and ultrasonic welding is performed. The edge of the electrode was welded to the positive and negative electrode current collectors.

The fold processing is performed by a press, and the valleys of the folds are concave, and the ridges of the folds are linearly pressed at intervals with a plurality of flat linear press parts spaced apart. I went.

This power generating element is connected to an oblong battery container (50
(mm × 130 mm × height 210 mm) and sealed. As shown in the schematic perspective view of the wound body in which the connection member is arranged in FIG.
° folded. Then, a columnar terminal member is inserted into a circular hole provided in each connection member and fixed by welding. This is inserted into a container, and the terminal members (to be a positive electrode terminal portion and a negative electrode terminal portion) are passed therethrough. A top plate with a circular hole (an insulating tube was filled in this hole) was attached from above, and this was sealed with a container by welding. Next, into this battery container, an electrolytic solution obtained by dissolving 1 mol / l (liter) of lithium hexafluorophosphate (LiPF6) in a 1: 1 (volume ratio) mixed solution of ethylene carbonate and dimethyl carbonate was injected under reduced pressure. . The capacity of this battery was 10 Ah.

[Example 2] In Example 1, after forming both ends of the electrode by creasing, a positive electrode current collector (10) and a negative electrode current collector (11) are attached instead of FIG. A battery of Example 2 was produced in the same manner as in Example 1 except that both end edges and the positive and negative electrode current collectors (12) and (13) with creases between them were attached as shown in FIG. .

COMPARATIVE EXAMPLE 1 Instead of mounting the positive electrode current collector (10) and the negative electrode current collector (11) after forming the electrodes at both ends in the embodiment, as shown in FIG. Positive and negative electrode current collectors (14), (1
A battery of Example 2 was made in the same manner as Example 1 except that 5) was attached.

In the first and second embodiments and the first comparative example, constant-current charging was performed at room temperature at 5 A corresponding to a 2-hour rate until the terminal voltage reached 4.1 V. Charged for hours. These batteries have a time span of 11
A half-sine impact with a peak of 70 G was applied 5 times in milliseconds, the open-circuit voltage of the battery after the application was confirmed, and the battery was disassembled to confirm the state of damage of the battery member. Table 1 shows the results.
Shown in Further, a vibration with an acceleration of 10 G and a frequency of 12 to 100 Hz was applied to these batteries for 5 hours, and the open-circuit voltage of the batteries during the application of the vibrations and the damage of the battery members were checked. Table 2 shows the results.

[0022]

[Table 1]

[0023]

[Table 2]

As shown in Table 1, in Examples 1 and 2, no change was observed in the open circuit voltage of the battery even when an impact was applied, and no damage or deformation was found in the battery member including the current collector. On the other hand, in Comparative Example 1, immediately after the third impact was applied, the open-circuit voltage of the battery dropped to 0 V, and as a result of dismantling the battery, the bent portion of the positive electrode current collector was broken, and its end was connected to the negative electrode current collector. A short circuit with the conductor was confirmed.

As shown in Table 2, in Examples 1 and 2, no change was observed in the battery open voltage during application of vibration, and no damage or deformation was found in the battery members including the current collector. On the other hand, in Comparative Example 1, 3 hours 20
A minute later, the open-circuit voltage of the battery changed, and the voltage dropped to 0 V after 3 hours and 30 minutes. As a result of dismantling the battery, the bent part of the positive electrode current collector was broken,
It was confirmed that the end was short-circuited with the negative electrode current collector.

As described above, by applying the fold processing of the present invention to the current collector, the reliability of the battery can be improved without impairing the simplicity of the battery assembling process.

In the above embodiment, the elliptical electrode group is used. However, the shape of the electrode group is not limited to this, and may be cylindrical. Further, the shape of the connection member is not limited to that of the embodiment, and for example, a shape as shown in FIG. 9 can be used.
It is preferable to apply a linear discontinuous fold processing (in this case, formed at both end edges) as shown in FIG.
Further, the form of the fold processing of the current collector is not limited to those shown in FIGS.
As shown by 0 to 12, various forms can be used as long as they are linear and discontinuous.

The present invention is particularly effective when the material of the connecting member is aluminum. This is because aluminum is particularly weakened by bending.

[0029]

According to the present invention, it is possible to provide a battery which can easily bend the connecting member and has high reliability against vibration and impact.

[Brief description of the drawings]

FIG. 1 is a plan view of a positive electrode structure.

FIG. 2 is a plan view of a negative electrode structure.

FIG. 3 is a schematic perspective view of a power generation element.

FIG. 4 is a schematic perspective view of a wound body.

FIG. 5 is a schematic perspective view of a wound body on which connection members are arranged.

FIG. 6 is a schematic perspective view of a wound body on which connection members are arranged.

FIG. 7 is a schematic perspective view of a wound body on which connection members are arranged.

FIG. 8 is a schematic perspective view of a wound body on which connection members are arranged.

FIG. 9 is a schematic perspective view of a wound body on which connection members are arranged.

FIG. 10 is a schematic perspective view of a wound body on which connection members are arranged.

FIG. 11 is a schematic perspective view of a wound body on which connection members are arranged.

FIG. 12 is a schematic perspective view of a wound body on which connection members are arranged.

[Explanation of symbols]

 10, 12, 14: Positive current collector as connecting member 11, 13, 15: Negative current collector as connecting member

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5H022 AA09 AA18 BB02 CC08 CC12 CC16 5H024 CC02 CC12 DD11 5H029 AK03 AL06 AL07 CJ03 DJ05

Claims (2)

[Claims] 1. A battery comprising a plate-shaped connecting member for electrically connecting a terminal portion and an electrode, wherein the connecting member has a bent portion, and the bent portion has a linear discontinuous fold. A battery characterized by being processed. 2. The battery according to claim 1, wherein the electrode is housed in a battery container as a wound body wound via a separator.