JPH09171818A - Nickel-metal hydride storage battery and its preparation - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the generation of short-circuiting caused by the contact of an anode with a cathode by forming an insulating layer in the edge part of at least one electrode of the cathode and the anode. SOLUTION: An insulating layer 20 made of synthetic resin is formed by coating and drying in the edge part of at least one electrode of a sheet-shaped cathode 1 containing a metal oxide or a metal hydroxide and a sheet-shaped anode 2 containing a hydrogen storage alloy. The cathode 1 and the anode 2 are spirally wound through an insulating separator 3 to form an electrode group 4. The spirally wound cylindrical electrode group 4 is inserted into a case 5. An electrolyte is filled in the case 5, and a sealing body 8 is fit to the opening of the case 5 through a gasket 7.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a nickel-metal hydride storage battery and a method for manufacturing the same, and more particularly to an active material in which an insulating material of a resin agent is applied to the edge of an electrode wound inside a case. The present invention relates to a nickel-metal hydride storage battery designed to prevent the occurrence of shots and the like due to falling off, and a manufacturing method thereof.

[0002]

2. Description of the Related Art Generally, a nickel-metal hydride storage battery is a hydrogen storage alloy in which hydrogen is reversibly stored by an electrochemical reaction in an alkaline electrolyte as in the solid or gas reaction of a hydrogen storage alloy and hydrogen gas. However, when the hydrogen storage alloy is used as an electrode to cause a reduction reaction in the alkaline electrolyte, water is decomposed and hydrogen and hydroxide ions are generated on the surface of the hydrogen storage alloy. As a result, the hydrogen generated from the hydrogen storage alloy is diffused and stored inside the alloy to generate a metal hydride and carry out a filling reaction.

Further, on the contrary, the hydrogen in the metal hydride which causes the oxidation reaction reacts with the hydroxide ion on the surface of the alloy to generate water, thereby causing the discharge reaction.

As shown in FIG. 1, the structure of such a nickel-metal hydride storage battery has a sheet-like anode (1) containing a metal oxide or a metal hydroxide, and a sheet containing a hydrogen storage alloy. -Shaped cathode (2) and said anode (1),
And a separator (3) for interposing insulation between the cathode and the cathode (2) to form an electrode group (4) which is spirally wound to form an electrode group (4). The case (5), which also serves as a cathode terminal, is tightly inserted, and the case (5) and the cathode (2) are connected by a cathode lead wire (6).

Further, a sealing body (8) having an anode cap (8a) formed on the upper side is mounted inside the upper side of the case (5) through an annular packing (7), and the sealing body is formed. In (8), a metal spring (9) for elastically raising the sealing body to release the gas in the atmosphere into the atmosphere when the pressure inside the battery rapidly rises is provided. (8) and the anode (1) are electrically connected by the anode lead wire (10).

[0006]

By the way, in the conventional nickel-metal hydride storage battery configured as described above, the anode and the cathode are spirally wound at the start end portions thereof being contacted with each other, or The upper and lower edges of the anode and the cathode are contacted with each other, or the active material that is a hydrogen storage alloy formed on the surface of the electrode during the manufacturing process progresses during charging / discharging. However, there is a problem in that the life of the storage battery is significantly shortened and the capacity is reduced.

Further, in order to solve the above problems, the separator interposed between the anode and the cathode is formed to have different weights and wall thicknesses to prevent the deterioration of the cycle life due to a short circuit. A nickel-metal hydride storage battery having a satisfactory capacity is also disclosed
It is disclosed in Japanese Patent Publication No. 59957 and Japanese Patent Publication No. 3-39958.

By the way, not only the supply of the electrolytic solution becomes difficult, but also the electrolytic solution is not evenly distributed between the electrode groups, and there is a problem in stability due to an increase in pressure due to the generation of gas. When the wall is thin, the defective rate increases due to shots, and when the separator is heavy or the wall is thick, the battery capacity is reduced. There was a problem that the work of inserting it inside was extremely difficult.

Therefore, the present invention has been made to solve the above-mentioned various problems, and an object of the present invention is to always maintain a constant distance between an anode and a cathode. Thus, it is to provide a nickel-metal hydride storage battery, which can prevent the occurrence of shots due to contact between the cathode and the anode to significantly reduce the defective rate, and further extend the life of the storage battery, and a manufacturing method thereof. .

[0010]

In order to achieve the above object, a nickel-metal hydride storage battery according to the present invention comprises an anode containing a metal oxide or a metal hydroxide,
In a storage battery provided with a cathode containing a hydrogen storage alloy, the anode, a separator interposed between the cathode,
An insulating layer is applied and formed on an edge of at least one of the anode and the cathode.

Further, in the method for manufacturing a nickel-metal hydride storage battery according to the present invention, after winding a positive electrode and a negative electrode via a separator, an electrode group is formed and the electrode group is inserted into a case. Then, in the method of manufacturing a storage battery by filling the inside with an electrolyte solution and tightly inserting a sealing body having an anode cap on the upper side, a synthetic resin is applied to an edge portion of at least one of the anode and the cathode. After that, a step of drying to form an insulating layer is included.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described in detail below with reference to the accompanying drawings 2 and 4.

In the figure, the same structure as the conventional structure is given the same name and the same reference numeral, and the detailed description is omitted.

First, according to the present invention, a sheet-shaped anode (1) containing a metal oxide or a metal hydroxide and a sheet-shaped cathode (2) containing a hydrogen storage alloy are provided at the edge of at least one electrode. An insulating layer forming step of applying and drying an insulating layer (20) of a synthetic resin material, and a separator (3) of an insulating material between the anode (1) and the cathode (2), and then a spiral shape. A winding step of winding the electrode group (4) to form an electrode group (4), and a step of inserting the cylindrical electrode group (4) formed in the winding step into the case (5); The process comprises the steps of filling the inside with an electrolytic solution such as caustic, and fixing the sealing body (8) to the upper opening via the packing (7).

Further, in the step of forming the insulating layer, as shown in FIG. 4A, an edge portion of the anode (1) or the cathode (2), for example, a start end portion of an electrode wound via a separator (3). An insulating layer (20) having a predetermined width is vertically formed by coating.

The insulating layer (20) is not limited to one vertically formed at the starting end of the anode (1) or the cathode (2), and for example, as shown in FIG. ), Or an insulating layer (20) can be formed on one of the upper and lower edges of the cathode (2),
As shown in FIG. 4C, an insulating layer (20) may be formed on the starting end and the upper and lower side edges of the anode (1) or the cathode (2), or as shown in FIG. It is also possible to form an insulating layer (20) having a predetermined thickness and width on the left, right, and upper edges of the cathode (2) or the cathode (2).

The insulating layer (20) is preferably made of a synthetic resin, more preferably a thermosetting resin such as a phenol resin, an epoxy resin, a silicon resin or the like, or a thermoplastic resin. Resin, for example
Polyethylene, polypropylene, fluororesin, etc. may be applied.

Further, the insulating layer (20) is formed by immersing the edge portion of either one of the anode (1) and the cathode (2) in a liquid resin and then drying it. Alternatively, it can be applied by means such as spraying or brushing, and if the thickness of the insulating layer (20) is thinner than 0.05 mm, the insulation between the electrodes will be poor, and the thickness will be thicker than 0.3 mm. In this case, it becomes difficult to carry out a coating operation for forming a film having a predetermined thickness, so that it is preferable to form the film with a thickness of 0.05 mm to 0.3 mm.

Further, in the insulating layer forming step, the viscosity of the resin which facilitates the work of applying the insulating layer (20) is 5,000.
More preferably, about 50,000 CP is retained.

[0020]

【Example】

(Embodiment 1) Sintering method in which a nickel sintered body is used as a gas and is filled with nickel oxide or nickel hydroxide, and a porous metal is used as a gas and nickel oxide is added to the sintered body.
Alternatively, a face-type sheet-shaped anode (1) in which nickel hydride is impregnated is manufactured, and after the powder of the hydrogen storage alloy is pressure-bonded by using a porous metal such as a metal net, punching metal, or expanded metal as a gas, Sintering is performed, and the hydrogen storage alloy powder is made into a facet type by being impregnated with the gas made of the porous metal and dried,
The cathode (2) is manufactured by a facet method in which a sheet or the like is pressure-bonded by a place or the like.

Further, an epoxy resin is applied to the starting end and the upper and lower side edges of the cathode (2) so as to have a thickness of 0.1 mm to form an insulating layer (20), and the insulating layer (20) is formed. ) Is formed on the cathode (2) and the anode (1) on which the insulating layer (20) is not formed with the separator (3) interposed therebetween to form the electrode group (4). , Case (5)
After being inserted into the inside, the electrolytic solution is charged, and the sealing body (8) having the anode cap (8a) is connected to the upper opening of the case (5) through the packing (7) to form a storage battery. I got up.

At this time, the defective rate due to shots at the initial stage or during charge / discharge of the storage battery manufactured according to the present invention is shown in Table 1.
Table 2 shows the deterioration rate of the storage battery due to the cycle characteristics during charging and discharging.

(Embodiment 2) Epoxy resin having a thickness of 0.1 mm is vertically provided on the edges of the starting ends of the anode (1) and the cathode (2) manufactured by the same method as in the above-mentioned Embodiment 1. To form an insulating layer (20), which is wound around the anode (1) and the cathode (2) with a separator (3) interposed therebetween to form an electrode group (4). A storage battery was manufactured in the same manner as in Example 1.

Further, the defective rate by the shot of the storage battery manufactured according to the present invention at the initial stage or during charging / discharging is shown in Table 1.
Table 2 shows the deterioration rate of the storage battery due to the cycle characteristics during charging and discharging.

(Comparative Example 1) The anode (1) and the cathode (2) manufactured in the same manner as in Example 1 were cut at the upper and lower edges and the left and right edges in a rounded state without any treatment. An electrode group (4) is formed between the anode (1) and the cathode (2) through a separator (3), and the rest is the initial stage of a storage battery manufactured in the same manner as in Example 1, or The defective rate due to shots during charging and discharging is shown in Table 1.
Table 2 shows the deterioration rates of the storage batteries due to the cycle characteristics during charging and discharging.

COMPARATIVE EXAMPLE 2 An anode (1) and a cathode (2) manufactured in the same manner as in Example 1 were wound around an auxiliary end septum and a separator (3) having a length of about 5 mm at the starting end. ) And then wound to form an electrode group (4), and the remainder is shown in Table 1 as a defective rate at the initial stage of a storage battery manufactured by the same method as in Example 1 or by a shot at the time of charging / discharging. Table 2 shows the deterioration rate of the storage battery due to the cycle characteristics during charging and discharging.

(Comparative Example 3) A separator (3) is made of a nylon resin and a polypropylene resin having different materials between an anode (1) and a cathode (2) manufactured in the same manner as in Example 1. The electrode group (4) is formed by using the same method, and the residual is shown in Table 1 as a defective rate due to shots at the initial stage or charging / discharging of the storage battery manufactured by the same method as in Example 1. Table 2 shows the deterioration rate of the storage battery depending on the characteristics.

[0028]

[Table 1]

[0029]

[Table 2]

However, in the storage battery of Comparative Example 3, liquid leakage occurred due to an increase in pressure due to the generation of gas from the storage battery at 50% during charging and discharging.

In the above-mentioned embodiment and the like, the closed-cylindrical nickel metal hydride storage battery is shown and described, but the present invention is not limited to this, and it is needless to say that the present invention can be applied to, for example, a prismatic nickel-metal hydride storage battery. Yes.

[0032]

As described above, according to the present invention, the anode,
Alternatively, by forming an insulating layer having a predetermined thickness on the winding start end, winding end, and upper and lower edges of the cathode, the shot due to the contact between the anode and the cathode due to the impact applied from the outside of the storage battery. And the defect rate can be minimized, which further extends the life of the storage battery and improves the charge / discharge characteristics.

[Brief description of the drawings]

FIG. 1 is an overall vertical cross-sectional view showing a normal nickel-metal hydride storage battery.

FIG. 2 is an overall vertical cross-sectional view showing a nickel-metal hydride storage battery applied to the present invention.

FIG. 3 is a partially enlarged vertical sectional view showing a main part of the present invention.

4 (A), (B), (C), and (D) are perspective views showing different aspects of an electrode formed according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Anode 2 ... Cathode 3 ... Separator 4 ... Electrode group 5 ... Case 8a ... Anode cap 8 ... Sealing body 20 ... Insulating layer

Claims (5)

[Claims] 1. A storage battery comprising: an anode containing a metal oxide or a metal hydroxide; a cathode containing a hydrogen storage alloy; and a separator provided between the anode and the cathode. Alternatively, the nickel-metal hydride storage battery is characterized in that at least one of the electrodes in the cathode is coated with an insulating layer on the edge thereof. 2. The nickel-metal hydride storage battery according to claim 1, wherein the insulating layer is made of synthetic resin. 3. An electrode group is formed after being wound between the anode and the cathode via a separator, the electrode group is inserted into a case, and the inside is filled with an electrolytic solution. A method for manufacturing a storage battery by tightly inserting a sealed body having a cap, including a step of applying a synthetic resin to an edge portion of at least one of the anode and the cathode, and then drying to form an insulating layer. And a method for manufacturing a nickel-metal hydride storage battery. 4. The thickness of the insulating layer is 0.05 to 0.3 mm
The method for manufacturing a nickel-metal hydride storage battery according to claim 3, wherein 5. The insulating layer comprises phenol resin, epoxy resin, silicon resin, polyethylene, polypropylene,
The method for manufacturing a nickel-metal hydride storage battery according to claim 3, wherein the method is one of fluororesins.