JPH08153515A - Electrode of spiral type electrode - Google Patents

Abstract

PURPOSE: To provide electrodes for use in a spiral type battery by which the durability and reliability of the battery are enhanced by preventing undesired deformation of long-size sheet-shaped electrodes when they are curved into spirals. CONSTITUTION: A plurality of linear grooves 60, 70 for reducing winding distortion are formed on the respective inside principal planes of long-size sheet- shaped positive and negative electrodes 6, 7 and approximately along their cross direction, the electrodes curved into spirals. Thus when the long-size sheet-shaped electrodes 6, 7 are curved into spirals the inside principal planes of the electrodes 6, 7 are pressed, and pulling of the outside principal planes due to the reaction of the pressing can be reduced or prevented. Also, the inside principal planes can be kept from swelling to the inside of bores and cracking, with the result that the durability and reliability of the battery can be enhanced.

Description

Detailed Description of the Invention

[0001]

FIELD OF THE INVENTION The present invention relates to electrodes for spiral wound batteries.

[0002]

2. Description of the Related Art A conventional spiral type battery has a spiral electrode assembly in which a pair of long sheet-like electrodes which are a positive electrode and a negative electrode are spirally formed with a separator interposed therebetween.

[0003]

However, in the conventional spiral type battery described above, when the long sheet-shaped electrode is curved in a spiral shape to form a spiral body, the inner main surface of the electrode is pressed and As a reaction, the outer main surface may be pulled, the inner main surface may bulge radially inward, and the outer main surface may be cracked. Further, it is considered that the bulging may cause deterioration of durability of the separator.

The present invention has been made in view of the above problems, and improves the durability and reliability of a battery by preventing unavoidable deformation of the electrode when the long sheet electrode is curved in a spiral shape. It is an object of the present invention to provide a spiral wound battery electrode.

[0005]

The first structure of the present invention is as follows.
A spiral which is composed of a long sheet-shaped positive electrode and a negative electrode for forming a spiral body with a separator interposed therebetween, and a plurality of groove grooves are formed in parallel on the inner main surface in a substantially width direction. It is an electrode of a battery. In a second configuration of the present invention, in addition to the first configuration, the groove is formed with a higher density on the small diameter side of the spiral body than on the large diameter side of the spiral body. It is characterized by that.

According to a third structure of the present invention, in addition to the first structure, the groove is formed wider on the small diameter side of the spiral body than on the large diameter side of the spiral body. It is characterized by

[0007]

In the first structure of the present invention, a plurality of linear grooves for reducing winding distortion are formed in the widthwise direction on the inner main surface of the long sheet-like electrode which is curved and becomes a spiral body. Since it is formed at a predetermined interval, the inner main surface of the electrode is pressed when the long sheet electrode is curved in a spiral shape to form a spiral body, and the outer main surface is pulled as a reaction. Or, it is possible to prevent bulging in the inner main surface in the radial direction and cracks on the outer main surface, and as a result, it is possible to improve the durability and reliability of the battery. it can.

The second structure of the present invention further increases the groove density on the small diameter side of the spiral body as compared with the large diameter side of the first structure. It is possible to improve. The third configuration of the present invention is the above first aspect.
In the above configuration, since the width of the groove is made larger on the small diameter side of the spiral body than on the large diameter side thereof, it is possible to further improve the action and effect.

[0009]

【Example】

(Embodiment 1) FIG. 1 shows a cross-sectional view of a spiral wound battery according to an embodiment of the present invention. This battery includes a metal can body 1 that constitutes a negative electrode terminal, a resin lid 2 that seals the upper end opening of the can body portion 1, and a positive electrode terminal 3 that projects from the center of the lid 2. ,
Electrolyte solution 4 and electrode assembly 5 housed inside can body 1
The electrode assembly 5 is composed of a sheet-shaped positive electrode 6 and a negative electrode 7 that are formed in a spiral shape with an ion-permeable and electrically insulating separator (not shown) interposed therebetween.

A tab 71, which is a conductive metal piece for collecting current, extends downward from the negative electrode 7, and a lower end portion of the tab 71 is welded to a bottom surface of the can body portion (negative electrode terminal) 1. The positive electrode terminal 3 is a conductor formed in the shape of a flanged terminal, and is fitted in the central hole of the lid 2. A core hole 8 is axially penetrated in the center of the electrode assembly 5 in the radial direction, and a heat dissipation rod 9 is penetrated into the core hole 8. The heat radiating rod 9 is a copper rod, and a disc 91 made of copper is welded to its upper end surface. Disk 9
A concave portion having an upper opening is provided in the central portion of 1, and the lower end portion of the positive electrode terminal 3 is fitted in and welded to this concave portion. The peripheral portion of the disc 91 is in close contact with the lower surface of the lid 2. A tab 61, which is a collector of the positive electrode 6, projects upward from the upper end of the positive electrode 6, and the upper end of the tab 61 is welded to the disc 91. After welding with the circular plate 91, the surface of the heat dissipation rod 9 is coated with a silicon resin film (not shown) having a thickness of about 3 μm, and the lower end surface of the heat dissipation rod 9 is covered with the silicon resin film to form the can body portion 1. It is in contact with the bottom so that it can be electrically insulated.

The electrode assembly 5 is constructed as follows. First, a nickel hydroxide paste is pressure-bonded to an expanded metal as a current collector made of nickel to form a long sheet-shaped positive electrode 6 having a thickness of about 0.7 mm, a width of about 190 mm, and a length of about 800 mm (Fig. 2). After that, a plurality of grooved grooves 60 having a depth of about 0.3 mm and a width of about 0.5 mm were formed at a predetermined pitch on a main surface (which will be referred to as an inner main surface) that is an inner side when spirally wound. Each groove 60 has a respective positive electrode 6
Is extended in the width direction of the
It may be installed obliquely within an angle range of 0 degrees. The groove 60 is
Approximately 10 mm at the outermost part when wound in a spiral shape
It is formed with a pitch, and is formed with a pitch of about 3 mm at the innermost portion when wound in a spiral shape, and the pitch is gradually narrowed from the outer peripheral side to the inner peripheral side. This is for the following reason. Assuming that the thickness of the long sheet-shaped positive electrode 6 is t, and that one turn of the spiral body is a perfect circular cylinder, the radius of its inner main surface is ri, and its wall thickness is t. The perimeter is 2πt more than the perimeter of the outer major surface. Therefore, the total width of the groove 60 for one turn of the spiral body is about 2
If πt, the above excess will be eliminated. This is equivalent to securing a total width of 2πt per circumferential length of 2πri of the inner main surface, so that the pitch of the groove 60 is p (m).
m) and the width of the groove 60 is d (mm), d / p is t
It can be seen that it should be approximately equal to / ri.

Next, the negative electrode 7 will be described. Negative electrode 7
Is a MmNi _3.5 Co _0.7 Al _0.8 mechanically 100 mesh or less of powder of hydrogen absorbing alloy powder of the composition of, performs an electroless copper plating as a plating amount of 20% of the total amount by using a commercially available plating solution , This copper plating alloy powder 25
After adding 1.3 g of PTFE dispersion (D-1 manufactured by Daikin Industries, Ltd.) to g, and kneading and preforming into a sheet, 300 ° C., 300 kg / 300 ° C. on both sides of the nickel expanded metal. It was crimped with cm ² . After that, in the same manner as the groove 60 of the positive electrode 6, the groove 70 (see FIG.
(See) was formed. Of course, it is also possible to form the groove 70 at the time of pressure bonding to the nickel expanded metal.

Next, the positive electrode 6 and the negative electrode 7 are wound with a separator (not shown) made of polyamide nonwoven fabric sandwiched therebetween to produce an electrode assembly 5 (see FIG. 3), and 5N KOH + 1N is used as an electrolytic solution. A battery was prepared using a LiOH aqueous solution. A partially enlarged side view of the negative electrode 7 is shown in FIG. In this embodiment, the groove 70 has a semicircular cross section. Of course, the cross section of the groove 60 or 70 may be modified in various ways, for example, it may be V-shaped, and groove 70a, 70b having different depths or widths may be formed in a predetermined order (FIG. 5). (Embodiment 2) Another embodiment will be described.

In this embodiment, the groove 6 of the first embodiment is used.
The pitch of 0 is formed more densely on the small diameter side of the electrode assembly (spiral) than on the large diameter side.
That is, since the curvature of the positive electrode 6 and the negative electrode 7 on the small diameter side is larger than that on the large diameter side, the pitch of the groove 60 is continuous from the large diameter side of the positive electrode 6 and the negative electrode 7 to the small diameter side. It will increase rapidly.

By doing so, the bending stress of the positive electrode 6 and the negative electrode 7 can be effectively eliminated. (Embodiment 3) In this embodiment, the groove 6 of Embodiment 1 described above is used.
The width of 0 is formed wider on the small diameter side of the electrode assembly (spiral) than on the large diameter side. That is, since the curvature of the positive electrode 6 and the negative electrode 7 on the small diameter side is larger than that on the large diameter side, the width of the groove 60 is continuous from the large diameter side of the positive electrode 6 and the negative electrode 7 to the small diameter side. It will increase rapidly.

By doing so, the bending stress of the positive electrode 6 and the negative electrode 7 can be effectively eliminated.

[Brief description of drawings]

FIG. 1 is a cross-sectional view showing an embodiment of a spiral wound battery of the present invention.

FIG. 2 is a perspective view showing a state before winding the positive electrode of FIG.

FIG. 3 is a partial plan view of the electrode assembly of FIG.

FIG. 4 is a partial plan view showing a state before winding the negative electrode of FIG.

5 is a partial plan view showing a state before winding of a modified example of the negative electrode of FIG. 1. FIG.

[Explanation of symbols]

Reference numeral 5 is an electrode assembly, 6 is a positive electrode (electrode), 7 is a negative electrode (electrode), and 60 and 70 are grooves.

Claims (3)

[Claims] 1. A long sheet-like positive electrode and a negative electrode for forming a spiral body with a separator interposed therebetween, and a plurality of grooved grooves formed on an inner main surface in parallel in a substantially width direction. Electrodes for spiral type batteries characterized by: 2. The electrode of the spiral battery according to claim 1, wherein the groove is formed at a higher density on the small diameter side of the spiral body than on the large diameter side of the spiral body. 3. The spiral battery electrode according to claim 1, wherein the groove is formed wider on the small diameter side of the spiral body than on the large diameter side of the spiral body.