JPH0620718A - Cylindrical hydride secondary battery - Google Patents

Abstract

(57) [Abstract] [Purpose] To improve the current collecting structure of the negative electrode in a cylindrical hydride secondary battery to increase the battery capacity. [Structure] Positive electrode 1 containing metal oxide or metal hydroxide
And a negative electrode 2 containing hydrogen storage alloy powder, and both electrodes 1,
An electrode 4 is formed by spirally winding a separator 3 interposed between the spirally wound electrode 2 and the separator 3, and the spirally wound electrode 4 is housed in a negative electrode can 5 together with an electrolytic solution containing an alkaline aqueous solution. In the cylindrical hydride secondary battery in which the current collector exposed portion 2a of the negative electrode 2 located at the outermost periphery of the negative electrode 2 is brought into contact with the inner peripheral surface of the negative electrode can 5 and the can opening is provided with a sealing body, The body exposed portion 2a is compressed in the thickness direction of the negative electrode 2 to form a thin wall.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cylindrical hydride secondary battery, and more particularly to improvement of a current collecting structure for a molded negative electrode.

[0002]

2. Description of the Related Art Generally, a battery of this type has a positive electrode 10 containing a metal oxide or a metal hydroxide, as shown in FIG.
And a negative electrode 20 containing a hydrogen storage alloy and a separator 30 interposed between the two electrodes are overlapped and spirally wound to form an electrode 40. It is housed in a cylindrical negative electrode can 50, and a sealing body (not shown) is provided at the can opening.

Here, as the negative electrode 20, as shown in FIG. 4, for example, a sheet-shaped molded body in which a hydrogen storage alloy powder 20B is pressure bonded to a nickel-made current collector 20A is used. The current collector 20A has a three-dimensional structure processed into, for example, an expanded metal so as to be advantageous for including the hydrogen storage alloy powder 20B as the active material, and the thickness thereof is that of the negative electrode 20. About the same as the thickness.

Further, in order to enhance the current collecting effect, as shown in FIGS. 4 and 5, the end portion of the nickel current collector 20A located at the outermost periphery of the electrode 40 is exposed as a current collector exposed portion 20a. , The inner surface of the negative electrode can 50 is contacted. The current collector exposed portion 20a is generally constituted by a portion obtained by removing the hydrogen storage alloy powder 20B from the negative electrode 20 or by welding an exposure current collector later.

[0005]

However, in the above-mentioned conventional current collecting structure, since the nickel current collector 20A is as thick as the negative electrode 20, it is occupied by the current collector exposed portion 20a. Space is relatively large. Therefore, even if an attempt is made to improve the electrode capacity, the occupied space of the exposed portion 20a restricts the increase in the amount of the active material filled.

The present invention has been made in order to solve the problems of the above-mentioned conventional ones, and improves the current collecting structure of the negative electrode,
It is an object of the present invention to provide a cylindrical hydride secondary battery capable of increasing the capacity.

[0007]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies in order to achieve the above-mentioned object. As a result, when forming a negative electrode containing a hydrogen-absorbing alloy powder, the position of the outermost periphery of the spiral electrode was determined. Focusing on the fact that if the exposed portion of the nickel current collector is made thinner, the occupied space when it is stored in the negative electrode can becomes smaller, and it is possible to increase the amount of active material such as hydrogen storage alloy powder by that amount. Then, the present invention was completed.

That is, according to the present invention, a positive electrode containing a metal oxide or a metal hydroxide, a negative electrode containing a hydrogen storage alloy powder, and a separator interposed between the two electrodes are spirally wound to form an electrode. This spiral electrode is housed in a negative electrode can together with an electrolytic solution consisting of an alkaline aqueous solution, and the exposed portion of the negative electrode current collector located at the outermost periphery of the spiral electrode is brought into contact with the inner peripheral surface of the negative electrode can. A tubular hydride secondary battery having a can opening with a sealing body, wherein the exposed portion of the current collector is compressed in the thickness direction of the negative electrode to form a thin wall. It relates to the next battery.

[0009]

In the present invention, since the current collector exposed portion of the negative electrode located at the outermost periphery of the spiral electrode is compressed in the thickness direction of the negative electrode and formed into a thin wall, the spiral electrode is placed in the negative electrode can. The space occupied by the exposed portion of the current collector when stored is reduced, and the amount of active material filled can be increased.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of the cylindrical hydride secondary battery of the present invention, and FIG. 2 shows the structure of a negative electrode used in the battery.

In FIG. 1, 1 is a positive electrode composed of a sheet-shaped molded product in which a metal oxide or metal hydroxide is pressure-bonded to a current collector as an active material, 2 is a negative electrode containing hydrogen storage alloy powder,
Reference numeral 3 is a separator interposed between these electrodes 1 and 2, and these electrodes are superposed and then spirally wound to form an electrode 4
The spiral electrode 4 is housed in a cylindrical negative electrode can 5 together with an electrolytic solution containing an alkaline aqueous solution, and an explosion-proof sealing member 6 is provided at the can opening. A lead 7 connected to the positive electrode 1 is spot-welded to the lower surface of the sealing body 6. 8
Is an insulating member between the sealing body 6 and the negative electrode can 5.

Here, as shown in FIG. 2, the negative electrode 2 is a sheet in which a hydrogen storage alloy powder 2B is pressure bonded to a current collector 2A.
The end portion 2a of the current collector 2A located at the outermost periphery of the spiral electrode 4 is exposed, and is compressed by the roller or the like from the thickness direction of the negative electrode 2 to be thin. Has been formed. This current collector exposed portion 2 compressed to a thin wall
As shown in FIG. 3, a is in contact with the inner peripheral surface of the negative electrode can 5. Therefore, the space occupied by the exposed portion 2a of the collector is reduced, and the capacity of the active material can be increased accordingly.

A battery A of the present invention having the above-mentioned structure,
In order to compare the performance with the battery B having the conventional configuration shown in FIG. 5, the discharge capacity characteristics and the defective rate at which the exposed portion of the current collector is defective in insertion were examined in the following manner. The number of tests was 50 for both batteries, and the average value is shown in Table 1 below.

In the battery A, the positive electrode 1 uses a nickel punching metal as a current collector, nickel oxyhydroxide as an active material, the negative electrode 2 uses a nickel expand metal as a current collector 2A, and the separator 3 has a separator 3. A nylon non-woven fabric was used. The battery B of the conventional configuration has the negative electrode current collector exposed portion 2
0a is about the same as the thickness of the negative electrode 20,
It is the same as the battery A.

<Discharge capacity characteristic> After charging 150% to each capacity at 0.1C, 0.2C, 0.7V
The step of cutting discharge was repeated several times, and the value at which the discharge capacity became stable was taken as the measured value.

<Defective Rate of Insertion of Electrode Can> When a spiral electrode was produced and inserted into a negative electrode can, the number of defective insertions caused by the exposed portion of the negative electrode current collector was examined.

[0017]

[Table 1]

As is clear from the above-mentioned test results, the battery A has a smaller amount of the current collector exposed portion 2a by being compressed, so that the amount of the active material filled therein is increased and the capacity of the battery A is higher than that of the battery B. I was able to. In addition, the battery A was able to significantly reduce the occurrence of the defective rate when inserting the can, as compared with the battery B.

In the above battery A, nickel metal expanded metal is used as a constituent material of the current collector 2A of the negative electrode 2, but a metal other than nickel may be used. In addition to expanded metal, various materials such as punching metal, foamed metal, and metal fiber may be used as long as they are conductive and can be filled with the hydrogen storage alloy powder 2B as an active material. it can.

[0020]

As described above, the use of the negative electrode current collecting structure of the present invention allows the active material to be increased in proportion to the reduction of the space occupied by the exposed portion of the current collector, resulting in a large capacity. A cylindrical hydride secondary battery can be obtained.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view showing an example of a cylindrical hydride secondary battery of the present invention.

FIG. 2 is a plan view showing a configuration of a negative electrode of the secondary battery.

FIG. 3 is a partial cross-sectional view showing a current collecting portion of a negative electrode of the secondary battery.

FIG. 4 is a plan view showing a structure of a negative electrode of a conventional cylindrical hydride secondary battery.

FIG. 5 is a partial cross-sectional view showing a current collecting portion of a negative electrode of a secondary battery having a conventional structure.

[Explanation of symbols]

 1: Positive electrode 2: Negative electrode 2A: Current collector 2B: Hydrogen storage alloy powder (active material) 2a: Current collector exposed part 3: Separator 5: Negative electrode can 6: Sealing body

Claims (1)

[Claims] 1. A positive electrode containing a metal oxide or a metal hydroxide, a negative electrode containing a hydrogen storage alloy powder, and a separator interposed between the two electrodes are spirally wound to form an electrode, The spiral electrode was housed in an anode can together with an electrolytic solution consisting of an alkaline aqueous solution, and the exposed portion of the negative electrode current collector located at the outermost periphery of the spiral electrode was brought into contact with the inner surface of the negative electrode can.
A cylindrical hydride secondary battery having a can opening with a sealing body, characterized in that the exposed portion of the current collector is compressed in the thickness direction of the negative electrode to form a thin wall. battery.