JPS6240819B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a sealed alkaline battery, and particularly to a so-called hermetic seal type battery that uses ceramics for its seal portion. In general, sealed alkaline batteries sealed with a sealing material such as glass or ceramics have a higher sealing effect at the sealed portion than those sealed with an organic sealing material such as rubber or resin. It has various advantages such as being stable and difficult to change. FIG. 1 is an enlarged view of a sealed portion of a conventional small-sized sealed alkaline battery 1 sealed by the hermetic seal. In the example shown in the figure, an annular insulating isolation member 4 made of ceramics is installed in an annular gap between a metal battery case 2 that also serves as an anode terminal and a metal cathode current collector lead 3 that penetrates the inside and outside of the case 2. This isolation member 4
and the current collector lead 3 and between the case 2,
Each is joined by a brazing layer 4b, and the battery 1
The inside is sealed. In this way, seal structures using ceramics are less susceptible to the cracks characteristic of glass than those that used only glass, and are expected to have better sealing effects, which can also improve leakage resistance. Be expected. By the way, in order to use the insulating isolation member 4 made of ceramic as a sealing material, a brazing material must be used as a bonding material between the ceramic and the metal portion. In FIG. 1, a metallized layer 4a is first provided on the surface of a ceramic part to be bonded to a metal part, and then the surface of the metallized layer 4a is covered with a plating layer 4c of nickel or the like, and the plating layer 4c and the metal The brazing layer 4b is used to connect the parts to each other by the brazing layer 4b. Here, the bonding member used for the brazing layer 4b is usually a brazing material containing at least silver or copper, so-called silver solder, or brass brazing material, and these brazing materials generally have a low brazing temperature (620 to 900
℃), and because it leaves no distortion in the ceramics after bonding, and the process cost is low. However, when the brazing material containing silver or copper is used as the above-mentioned bonding material to assemble a sealed alkaline battery, when the brazing material on the anode side comes into contact with the alkaline electrolyte, the silver or copper contained in the brazing material Or copper oxidizes and dissolves and migrates to the cathode side,
Due to its precipitation, the insulation state between the anode side and the cathode side becomes poor, resulting in self-discharge. In addition, the oxidative dissolution of silver or copper corrodes the area along the interface between the ceramic and the metal part, resulting in leakage, which is the most disliked problem in alkaline batteries. The above problems can be alleviated to some extent by coating the exposed surface of the brazing material with a bituminous material such as pitch. However, even if such measures were taken, the above-mentioned tendency appeared in the long-term stock, and no substantial improvement was achieved. This invention was made in view of the above-mentioned problems, and its purpose is to provide a sealed alkaline battery using ceramics for the sealing part, without impairing the characteristics of ceramics as an insulating isolation member. The purpose is to reliably prevent the occurrence of voltage failures due to self-discharge and leakage of alkaline electrolyte. Embodiments of the present invention will be described below with reference to the drawings. The main structure of the present invention is described in Part 1.
Since it is exactly the same as the figure, FIG. 1 will be referred to and the same reference numerals will be used. First, FIG. 2 explains the overall structure of a sealed alkaline battery to which the present invention is applied. The battery 1 according to the present invention consists of an anode 7a, a separator 7b, and a cathode 7c in a flat metal battery case 2. A power generation element 7 is loaded. This power generation element 7 uses a strong alkaline aqueous solution as an electrolyte. The battery case 2 has a metal current collector lead 3 that penetrates the inside and outside of the central part of the case 2 and has a sealing part 9.
It is maintained in an electrically insulated and isolated state by. The battery case 2 also serves as an anode terminal, and the current collector lead 3 also serves as a cathode terminal. In the seal portion 9, that is, the annular gap between the case 2 and the current collecting lead 3, an annular insulating isolation member 4 made of the above-mentioned ceramics is disposed. As shown in FIG. 1 and enlarged, a metallized layer 4a is formed on the surface of the isolation member 4, and a nickel plating layer 4c is formed on the surface of the metallized layer 4a. There is.
These layers 4a, 4c are partially formed only on the surface along the interface between the isolation member 4 and the metal portion.
That is, they are selectively formed only in portions along the respective interfaces between the inner circumferential surface of the annular boss portion 2a of the battery case 2 and the outer circumferential surface of the lead portion 3a of the current collecting lead 3. Note that the nickel plating layer 4c is not necessarily required, and a brazing layer 4b, which will be described later, can be directly bonded to the metallized layer 4a. Further, when providing the plating layer 4c, nickel plating is preferable in consideration of wettability with the brazing layer 4b. And between the plating layer 4c and the metal part,
A brazing layer 4b (the same reference numeral is used because the shape is exactly the same as the conventional one) made of a brazing material mainly composed of nickel and not containing at least silver and copper is interposed, and this brazing layer 4b is used as a bonding layer. By closely joining the insulating isolation member 4 to the current collector lead 3 and the battery case 2, the annular gap is closed air-tightly and liquid-tightly. As mentioned above, the brazing material constituting the brazing layer 4b is mainly composed of nickel, and contains at least silver,
It is a brazing filler metal that does not contain copper, such as nickel wax or BAU-4 standardized by JIS.
There are gold soldering materials such as BAU-4V whose main components are gold and nickel, and these soldering materials are provided as powder or wire rods. In addition, these brazing materials generally have a higher brazing temperature than brazing materials containing silver or copper, but the problem with these is that they cannot be brazed in a short time using, for example, high-frequency brazing or resistance brazing. By completing this process, the process can be carried out at low cost without causing distortion or cracking of the ceramics constituting the isolation member 4. It should be noted that among the above-mentioned brazing materials, in the case of a gold solder mainly composed of gold-nickel, a certain degree of oxidative dissolution is observed, and self-discharge may occur in a long-term stock. This is also said to be due to the fact that the gold component dissolves to some extent, although not as much as the dissolution effect seen in silver and copper. Therefore, in view of the above points and the increased cost of using gold, nickel wax is preferably used. Then, the brazing layer 4 configured as described above
Since the brazing filler metal contains nickel, the seal portion 9 with the b-interposed part has extremely good wettability with the plating layer 4c formed on the outer periphery of the isolation member 4, and a reliable sealing effect can be obtained. By not containing silver or copper, the brazing layer 4
There is also very little risk that b will be corroded by the alkaline electrolyte. Here, if the Nitrel plating layer 4c is not provided, the adhesion may be incomplete due to poor wettability between the metallized layer 4a and the brazing material, but in this case, the working conditions for brazing may be adjusted appropriately. The nickel plating layer 4c does not necessarily have to be provided because it can be made to such an extent that there is no problem in practical use. Therefore, poor insulation between both terminals, self-discharge caused by this, and leakage of alkaline electrolyte along the brazing layer 4c are also prevented. In addition, on the anode side, when the alkaline electrolyte comes into contact with the brazing filler metal, a local battery may be formed, and the brazing filler metal may oxidize and dissolve due to an electrochemical reaction, but on the cathode side, a local battery may also be formed. Since the cathode active material (such as Zn) is usually a metal that is electrochemically more base than the brazing filler metal, oxidative dissolution like that on the anode side is difficult to occur, so the isolation member 4 shown in FIG.
The brazing material mainly composed of nickel can be used only between the isolation member 4 and the case 2, and the conventional brazing material mainly composed of silver or copper can be used between the isolation member 4 and the current collecting lead 3. However, according to the experiments conducted by the present inventors, melting of the brazing filler metal was also observed on the cathode side, and although the reason is not clear, it is thought that it was chemically oxidized and dissolved, so nickel was also used on the cathode side. It is desirable to use a brazing filler metal as the main component. These selections were made in consideration of the distortion of the ceramics at high temperatures mentioned above, as well as manufacturing considerations when using separate brazing materials for the anode and cathode. , silver or copper as the main component. Now, here, the sealed alkaline battery (silver oxide battery) according to the present invention described in the above embodiments,
(using nickel wax, gold wax BAU-4)
and the voltage when 100 of each of the five conventional products (silver solder, one coated with pitch, and one using brass solder) were prepared and stored at a temperature of 60°C. When the number of defective products was investigated, the results shown in Table 1 were obtained.

[Table] The standard for voltage defects is a terminal voltage of 1.5V, and anything less than that is considered defective. As is clear from Table 1, the number of voltage failures that occur in batteries according to the present invention is lower than that of conventional batteries, and the number of voltage failures is extremely low, especially in batteries using nickel solder. This shows that the nickel used as the brazing material is hardly oxidized and dissolved in the alkaline electrolyte. It should be noted that conventional products coated with pitch are good at the initial stage, but as days pass, the number of defective products rapidly increases, clearly indicating that there is no fundamental solution. In addition, 50 batteries each of batteries according to the present invention and conventional batteries (5 items same as those in Table 1) were prepared and stored in an environment with a temperature of 60°C and a humidity of 90%, during which time leakage of alkaline electrolyte occurred. When the number of liquids generated was investigated, the results shown in Table 2 were obtained.

[Table] As is clear from Table 2, the battery according to the present invention has significantly improved leakage resistance performance compared to the conventional battery. The products of the present invention shown in Tables 1 and 2 above both use the brazing filler metal according to the present invention on both the anode side and the cathode side. In this case, the brazing material of the present invention is used only on the anode side,
When a conventional brazing material mainly composed of silver or copper is used on the cathode side, dissolution of the brazing material is observed on the cathode side as well, but it is not as noticeable as on the anode side.
There is no practical problem. Therefore, the brazing filler material on the cathode side can be selected from one containing nickel as a main component, or one containing silver or copper as a main component. As described above, the sealed alkaline battery according to the present invention, which uses ceramics for its sealing part, not only does not impair the properties of ceramics as a sealing material, but also has less voltage defects and has excellent leakage resistance. The results showed a significant improvement.

[Brief explanation of the drawing]

FIG. 1 is an enlarged sectional view showing the main structure of a sealed alkaline battery, and FIG. 2 is a sectional view showing the overall structure of the alkaline battery. DESCRIPTION OF SYMBOLS 1...Sealed alkaline battery, 2...Metal battery case, 3...Metal current collection lead, 4...Annular insulating isolation member, 4a...Metallized layer, 4b...Brazing layer, 7...Power generation element.

Claims (1)

[Claims] 1. An annular insulating isolation member made of ceramics is arranged between the annular gap between the metal current collector lead of the other electrode, which penetrates the inside and outside of the metal battery case that also serves as the terminal of one electrode, and the battery case side. , in a sealed alkaline battery in which the power generating element in the battery case is hermetically sealed by the isolation member and the anode side and the cathode side are insulated and isolated from each other, the battery is made of ceramics constituting the insulation isolation member; A metallized layer is formed along the interface with the metal part constituting the case and the current collector lead, and a material for bonding the ceramic and the metal part via this metallized layer is used in the battery case at least on the anode side. Alternatively, a sealed alkaline battery characterized in that a brazing material mainly composed of nickel and containing at least no silver or copper is used on either side of the current collecting lead.