JPH06267583A - Spiral-shaped cell - Google Patents

Abstract

PURPOSE:To increase the volume efficiency of a spiral shaped electrode body, and thereby make its capacity higher by letting the innermost circumferential section and the outermost circumferential section of the spiral shaped electrode body be constituted of a negative electrode, and letting the innermost circumferential section and the outermost circumferential section of the negative electrode be half of the other section in thickness. CONSTITUTION:A negative electrode 2 is made roughly two times as long as a positive electrode 1, and is made one half times as thick as the positive electrode, the positive electrode 1, the separator 3 and the negative electrode 2 are mutually piled up with one end sections of them aligned. The surplus section of the separator 3 and the negative electrode 3 are folded back to allow the negative electrode 2 to be piled up onto the other surface of the positive electrode 1 via the separator 3, and the end section of the negative electrode 2 at its folded side is wound around the winding shaft of a winder so as to be wound in a spiral shape. By this constitution, the innermost circumferential section 2a and the outermost circumferential, section 2b of a spiral shaped electrode body 4 are constituted of the negative electrode 2, its thickness is one half of that of a section 2c other than the negative electrode. Thereof ore, the entire section of the negative electrode 2 can be put to good use of cell reaction, so that the cell high in capacity can thereby be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spiral battery, and more particularly to a spiral battery in which the volume efficiency of the spiral electrode body is increased to achieve a high capacity.

[0002]

2. Description of the Related Art Conventionally, in a spiral battery provided with a spiral electrode body such as a spiral alkaline secondary battery, the capacity of the negative electrode is usually made larger than that of the positive electrode. This reduces the polarization during discharge, improves the flatness of the discharge voltage, and reduces the oxygen generated from the positive electrode during overcharge on the surface of the negative electrode, returning it to water and preventing the internal pressure of the battery from increasing. This is because.

By the way, when the spiral electrode body is used, the battery reaction is carried out on both surfaces of the electrode. However, because the capacity of the negative electrode is larger than the capacity of the positive electrode, the outermost peripheral portion of the spirally wound electrode body is composed of the negative electrode, but the outermost peripheral portion of this negative electrode is a reaction on only one side, and If the thickness is made to be the same as that of the other part, there is a problem that half of the part is not effectively used for battery reaction. Also,
Even when the innermost peripheral portion of the spirally wound electrode body is composed of a negative electrode, the innermost peripheral portion of the negative electrode has a reaction on only one side, and cannot be effectively used for battery reaction.

[0004]

SUMMARY OF THE INVENTION The present invention solves the problem that a part of the negative electrode of the spirally wound electrode body is not effectively used in the battery reaction in the conventional spirally wound battery as described above. It is an object of the present invention to provide a high-capacity spiral battery by increasing the volumetric efficiency of the electrode strip.

[0005]

According to the present invention, the innermost peripheral portion and the outermost peripheral portion of a spirally wound electrode body are constituted by a negative electrode, and the thickness of the innermost peripheral portion and the outermost peripheral portion of the negative electrode is set to other portions. The thickness of the spirally wound electrode body is increased to half, and the volumetric efficiency of the spirally wound electrode body is increased to achieve high capacity.

That is, in the present invention, the thickness of the innermost peripheral portion and the outermost peripheral portion of the negative electrode in which the battery reaction occurs only from one surface is half the thickness of the other portions in which the battery reaction occurs from both surfaces. The innermost part and outermost part of the battery are effectively used for the battery reaction like the other parts, and the innermost part and the outermost part of the negative electrode are not used for charging and discharging as in the conventional case. Will disappear. Therefore, by making the filling capacity of the positive electrode and the negative electrode proper, the volumetric efficiency of the spirally wound electrode body can be increased and a higher capacity can be achieved.

In the present invention, typical examples of the metal oxide and metal hydroxide used as the active material of the positive electrode include nickel monoxide (NiO), nickel dioxide (NiO ₂ ), nickel hydroxide ( Ni (OH)
₂ ] and the like. However, these are cases where the positive electrode is in a discharged state, and when the positive electrode is in a charged state, the metal oxide or metal hydroxide is present as another compound. Then, the positive electrode may be produced by using the above-mentioned active material by either a sintering method or a paste method.

As the active material of the negative electrode, hydrogen storage alloy, cadmium, iron, zinc or the like is used. However, these cadmium, iron, zinc, etc. exist when the negative electrode is in a discharged state, and when the negative electrode is in a charged state, they exist as another compound.

The hydrogen storage alloy is an alloy capable of reversibly storing and releasing hydrogen atoms, and is usually synthesized in the state where hydrogen atoms are completely desorbed (released). In the negative electrode using this hydrogen storage alloy, charging is storage of hydrogen atoms and discharging is release of hydrogen atoms. Examples of the hydrogen storage alloy include TiZrVNiCr-based alloys, LaZrNiAl-based, TiNi-based, and TiNiZr-based alloys.
It is possible to use various hydrogen storage alloys such as those based on MmNi ₅ series and MmNi ₅ series.

The negative electrode may be manufactured by either a sintering method (compression bonding method) or a paste method as long as it uses the above active material.

The electrolytic solution is composed of an alkaline aqueous solution,
As the alkaline aqueous solution, for example, an aqueous solution of an alkali metal hydroxide such as sodium hydroxide, potassium hydroxide or lithium hydroxide is used.

[0012]

EXAMPLES Next, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to only those examples.

Example 1 Commercially available Ti, Zr, V, Ni, Cr (all having a purity of 9
9.9% or more) of each sample is Ti ₁₇ Zr ₁₆ V ₂₃ Ni ₃₇ Cr
The composition was weighed so that it had a composition of ₇ , and was melted by heating in a high frequency melting furnace to obtain a multiphase alloy.

This alloy was evacuated to 10 ^-4 torr in a pressure vessel, purged with Ar three times, and then kept at a hydrogen pressure of 14 kg / cm ² for 24 hours, and then hydrogen was exhausted to 400 ° C. By heating at 0 ° C. to completely desorb hydrogen, a hydrogen storage alloy was obtained in the form of powder of 20 to 100 μm.

This hydrogen-absorbing alloy powder was pressure-bonded to a nickel current collector using a roll mill, held in an atmosphere of Ar / H ₂ = 99/1 at 875 ° C. for 12 minutes, sintered, and cooled to 30 ° C. After that, it was cut into a predetermined size to obtain a negative electrode sheet for winding.

This negative electrode sheet is made to have the same thickness as the thickness of the negative electrode at the innermost peripheral portion and the outermost peripheral portion of the spirally wound electrode body, and the dimensions are 0.29 mm in thickness and width × length. It was 39 mm × 121 mm.

The positive electrode comprises a nickel foam substrate having tab portions, 100 parts by weight of nickel hydroxide [Ni (OH) ₂ ], 20 parts by weight of nickel powder, 10 parts by weight of cobalt powder, and a 3% carboxymethylcellulose aqueous solution 60. 1 part by weight and 10 parts by weight of 60% polytetrafluoroethylene dispersion were filled, and the mixture was filled with a paste, dried at 80 ° C. for 1 hour, and then pressed at a pressure of about 5 tons to form a sheet-like molded product having a thickness of 0.85 mm. And get it 38mm
It is cut into a size of 66 mm.

The separator is made of nylon 6 and has a thickness of 0.1.
Using a 2 mm non-woven fabric cut into 41 mm × 140 mm, the positive electrode, the separator and the negative electrode were superposed so that the separator and the negative electrode were arranged on both sides of the positive electrode, and the spirally wound electrode body was produced.

When the positive electrode and the negative electrode are superposed, the length of the negative electrode is 123 mm, which is about twice the length of the positive electrode (66 mm). Therefore, the positive electrode, the separator and the negative electrode are superposed with one end aligned. And the remaining part of the negative electrode is folded back so that the negative electrode overlaps with the other surface of the positive electrode via the separator, and the end on the side where the negative electrode is folded back is wound around the winding shaft of the winding machine with a diameter of 3.5 mm. It was wound in a spiral.

As a result, the cross section of the spiral electrode body thus obtained is as shown in FIG. 1, and the innermost and outermost peripheral parts of the spiral electrode body 4 are composed of the negative electrode 2 and the negative electrode 2 thereof. The thickness of the innermost peripheral portion 2a and the outermost peripheral portion 2b is half the thickness of the other portion 2c. That is, in the spiral electrode body 4, the negative electrode sheet remains in the innermost peripheral portion 2a and the outermost peripheral portion 2b of the negative electrode 2 while keeping the same thickness, but the other portion 2c is the negative electrode sheet. Since the negative electrode 2 is formed in a two-layered state, the thickness of the innermost peripheral portion 2a and the outermost peripheral portion 2b of the negative electrode 2 is half the thickness of the other portion 2c (that is, 1 / 2).

FIG. 1 is a diagram schematically showing a cross section of the spirally wound electrode body in the spirally wound battery of the present invention.
In the figure, 1 is a positive electrode, 2 is a negative electrode as described above, and 3
Is a separator, and 4 is a spiral electrode body composed of these wound bodies.

Next, the spirally wound electrode body 4 was placed in a battery case, an electrolytic solution was injected therein, and the container was sealed to prepare the spirally wound battery shown in FIG.

Therefore, the battery shown in FIG. 2 will be described. 1, 2, 3, and 4 are the positive electrode and the positive electrode, respectively, as described above.
Negative electrode, separator, spiral electrode body, 5 is a battery case, 6 is an annular gasket, 7 is a sealing lid, 8 is a terminal plate, 9
Is a sealing plate, 10 is a metal spring, 11 is a valve body, 12 is a positive electrode lead body, 13 is an insulator, and 14 is an insulator.

The positive electrode 1 is connected to the lower portion of the sealing plate 9 by the positive electrode lead body 12, and although not shown in FIG. 2, the negative electrode 2 has a current collector at the outermost periphery of the spiral electrode body 4 which is a battery. It contacts the inner surface of the case 5 and thereby the negative electrode 2
And the battery case 5 can be electrically connected.

Prior to inserting the spiral electrode body 4 into the battery case 5, an insulator 13 is arranged on the bottom of the battery case 5, and an insulator 14 is arranged on the upper part of the spiral electrode body 4. .

The sealing lid 7 is composed of a terminal plate 8 and a sealing plate 9, and the opening of the battery case 5 is sealed by the sealing lid 7 and the annular gasket 6.

The terminal plate 8 is provided with a gas discharge hole 8a,
A gas detection hole 9a is provided in the sealing plate 9, and a metal spring 10 and a valve body 11 are arranged between the terminal plate 8 and the sealing plate 9. Then, the outer peripheral portion of the sealing plate 9 is bent to sandwich the outer peripheral portion of the terminal plate 8 to fix the terminal plate 8 and the sealing plate 9.

A 30% by weight aqueous potassium hydroxide solution was injected as an electrolytic solution into the battery, and the battery size was AA.
It is a shape.

Further, in this battery, under normal circumstances, the valve body 11 due to the pressing force of the metal spring 10 closes the gas detection hole 9a, so that the inside of the battery is kept sealed, but the inside of the battery is kept closed. When gas is generated in the battery and the internal pressure of the battery rises abnormally, the metal spring 10 contracts and a gap is created between the valve body 11 and the gas detection hole 9a. The gas is discharged to the outside of the battery through the gas discharge holes 8a, and the battery is prevented from bursting.

Comparative Example 1 The negative electrode had a width x length x thickness of 39 mm x 123 mm x 0.2.
9 mm, the positive electrode has a width x length x thickness of 38 mm x 92 m
m × 0.60 mm, the separator had a width × length × thickness of 41 mm × 240 mm × 0.12 mm, and other than those, in the same manner as in Example 1, a nickel-hydrogen storage alloy system was used as an AA alkaline secondary. A battery was made.

The spiral electrode body in the battery of Comparative Example 1 complies with the prior art, and its cross section is as shown in FIG. As is clear from FIG. 3, in the spirally wound electrode body 4 of the battery of Comparative Example 1, the negative electrode 2 has a uniform thickness throughout. In addition, the positive electrode 1 of Comparative Example 1
As is clear from comparison with the size of the positive electrode 1 of Example 1 shown in FIG. 1, the thickness is thinner and the length is longer than the positive electrode 1 of Example 1.

Each of the battery of Example 1 and the battery of Comparative Example 1 was stored at 60 ° C. for 17 hours, then charged at 100 mA for 15 hours, discharged at 200 mA to a battery voltage of 0.9 V, and the discharge capacity became constant. The charging and discharging were repeated until and the capacity when the discharge capacity became constant was measured. The discharge capacity at that time is shown in Table 1 together with the filling capacity.

[0033]

[Table 1]

As shown in Table 1, Example 1 has about 5% larger filling capacity and discharge capacity than Comparative Example 1. According to the present invention, the volume of the spirally wound electrode body is larger than that of the conventional product. It has been clarified that higher efficiency can be achieved and higher capacity can be achieved.

[0035]

As described above, according to the present invention, the innermost peripheral portion and the outermost peripheral portion of the spirally wound electrode body are constituted by the negative electrode, and the thicknesses of the innermost peripheral portion and the outermost peripheral portion of the negative electrode are other than that. The volume efficiency of the spirally wound electrode body can be increased and the capacity of the spirally wound battery can be increased by reducing the thickness of the portion to half.

[Brief description of drawings]

FIG. 1 is a schematic enlarged cross-sectional view of a cross-section of a spiral electrode body in a spiral battery of the present invention.

FIG. 2 is an enlarged vertical sectional view showing an example of the spiral battery of the present invention.

FIG. 3 is a cross-sectional view schematically showing a cross-section of a spirally wound electrode body in a conventional spirally-shaped battery in an enlarged manner.

[Explanation of symbols]

 1 Positive electrode 2 Negative electrode 3 Separator 4 Spiral electrode body

Claims (1)

[Claims] 1. A positive electrode 1 containing a metal oxide or a metal hydroxide as an active material, and a negative electrode 2 containing a hydrogen storage alloy, cadmium, iron or zinc as an active material, wound in a spiral shape with a separator 3 interposed therebetween. In a spiral battery including a spirally wound electrode body 4, an innermost peripheral portion and an outermost peripheral portion of the spiral electrode body 4 are composed of a negative electrode 2, and an innermost peripheral portion 2a and an outermost peripheral portion of the negative electrode 2 are formed. A spiral battery, wherein the thickness of 2b is half the thickness of the other portion 2c.