JPS6148218B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a small sealed battery, particularly a so-called hermetic seal type battery that uses ceramics for its sealing portion. In general, sealed batteries sealed with a sealant such as glass or ceramics are more effective at sealing than those sealed with an organic sealant such as rubber or resin. It has various advantages such as being high in quality, stable and resistant to deterioration. FIG. 1 is an enlarged view of the sealed portion of a conventional small sealed battery 1 sealed by the hermetic seal. In the example shown in the figure, an annular insulating isolation member 4 made of ceramics is arranged in an annular gap between a metal battery case 2 that also serves as an anode terminal and a cathode current collector lead 3 that penetrates the inside and outside of this case 2. The isolation member 4 and the current collecting lead 3 and the case 2 are connected by brazing layers 4b, and the inside of the battery 1 is sealed. In this way, seal structures using ceramics are less susceptible to the cracks characteristic of glass than previous structures that used only glass, resulting in a better sealing effect and improved leakage resistance. . However, in order to obtain such a sealing structure, it is first necessary to provide a metallized layer 4a along the bonding surface of the isolation member 4. Moreover, the metallized layer 4a must be provided only at the joint portion. Only after passing through such a troublesome preliminary process can the current collector lead 3 and the case 2 be brazed to each other. However, the seal structure constructed through such a complicated process was not necessarily stable. For example, in an alkaline battery, the metallized layer 4a
The metal that forms the seal dissolves into the alkaline electrolyte, and the metal used for brazing is also corroded by the alkaline electrolyte, making it difficult to maintain a stable seal over a long period of time. It becomes difficult. To make matters worse, those metals once dissolved in the alkaline electrolyte may appear as precipitates near the sealing part, resulting in a leakage current path or short circuit between the case 2 and the current collector lead 3. This results in the formation of a current path. Furthermore, metals such as silver and copper used for brazing meet an alkaline electrolyte to form a battery, causing an electrochemical reaction and being corroded. In order to prevent this, the metal used for the metallized layer 4a and the brazing must be a noble metal such as gold or platinum, but this is difficult to realize because it significantly increases the material cost. This invention was made in view of the above-mentioned problems, and its purpose is to improve the performance of both conventional glass-sealed products and conventional ceramic-sealed products as described above. It is possible to obtain a sealed state with significantly superior mechanical strength characteristics and chemical or electrochemical stability compared to the previous model, which further improves leakage resistance and prevents discharge defects. To provide a small-sized sealed battery which has very little amount of metal, which can be constructed without going through the troublesome preliminary process as mentioned above, which does not necessarily require precious metals such as gold or platinum, and which is excellent in manufacturing suitability and economic efficiency. There is a particular thing. Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIGS. 2a and 2b show an embodiment of a small sealed battery according to the present invention. First, the battery 5 shown in the figure has an anode 7 inside a flat battery case 6.
A, a power generating element 7 consisting of a separator 7b and a cathode 7c is loaded. This power generation element 7 uses a strong alkaline aqueous solution as an electrolyte. The battery case 6 holds a metal current collecting lead 8 that penetrates the inside and outside of the case 6 while being electrically insulated and isolated by a sealing part 9 .
The battery case 6 also serves as an anode terminal, and the current collection lead 8 serves as a cathode terminal. In the annular gap between the case 6 and the current collecting lead 8, an annular insulating isolation member 10 made of ceramic is disposed. This isolation member 10
and the interface between the lead portion 8a of the current collector lead 8 and its surroundings, and the annular boss portion 6a of the battery case 6.
Adhesive layers 11 made of glass are interposed along the interfaces with the respective parts. The adhesive layer 11 allows the isolating member 10 to be tightly joined to the current collector lead 8 and the battery case 6, thereby sealing the annular gap. Here, the ceramic forming the isolation member 10 has an extremely dense sintered structure so as to have sufficient airtightness. The adhesive layer 1
1 is preferably formed as thin as possible,
In the example, the thickness is approximately 50μ. In the step of forming such a seal structure, first, the isolation member 10 is placed in the annular gap portion.
After that, molten glass is infiltrated into the gap between the inside and outside of the isolation member 10. Therefore, the process does not include any particularly troublesome elements. Now, in the small sealed battery sealed as described above, first of all, since the ceramic forming the isolation member 10 occupies most of the annular gap, the mechanical strength of at least that part is high. Its properties are very good, and unlike glass, there is almost no risk of cracking. Furthermore, since the adhesive layers 11 interposed along the interfaces between the isolation member 10, the case 6, and the current collection lead 8 are made of garam, they do not dissolve in the alkaline electrolyte. It is possible to exhibit an extremely stable state chemically or electrochemically without causing any damage. Furthermore, since the glass of the adhesive layer 11 is interposed in a thin layered state, internal distortions that would lead to large cracks are less likely to occur, which is likely to cause cracks peculiar to glass. This drawback is overcome, and it becomes possible to ensure good mechanical strength properties in the adhesive layer 11. Even if some local cracks were to occur in the glass of the adhesive layer 11, the cracks would be difficult to grow along the direction in which the inside and outside of the battery case 6 are communicated, and therefore the sealing would be difficult. The effect on effectiveness is almost negligible. This results in significantly superior mechanical strength properties and chemical or electrochemical stability compared to either conventional glass seals or conventional ceramic seals as described above. As a result, the leakage resistance can be further improved, and the occurrence of discharge defects and the like can be significantly reduced. The following table shows the leakage resistance of battery A according to the present invention having the configuration of the above-described embodiment, battery B sealed with conventional glass, and battery C sealed using conventional ceramics described above. The results are shown when performance tests were conducted under the same conditions. The types of batteries A, B, and C used in the test were all silver oxide batteries (diameter 12 mm x
The height is 3 mm). The storage environment for the test was a temperature of 60°C and a humidity of 90%.

[Table] In addition, when we checked the discharge capacity of each battery that remained without any visible leakage in the above leakage resistance test (after 60 days), the number of batteries whose discharge capacity decreased by 50% or more was There were 0 pieces for battery A, 0 pieces for battery B, and 82 pieces for battery C. As described above, the small sealed battery according to the present invention can be obtained through a relatively simple manufacturing process compared to conventional batteries sealed using glass or ceramics, and moreover, it does not require the use of precious metals. It is possible to obtain extremely excellent mechanical strength characteristics and chemical or electrochemical stability without any problems, and this can greatly improve leakage resistance and reduce the occurrence of discharge defects. can.

[Brief explanation of the drawing]

FIG. 1 is a partially enlarged sectional view of an example of a conventional small sealed battery, FIG. 2 a is a sectional view of an embodiment of a small sealed battery according to the present invention, and FIG. 2 b
is an enlarged sectional view of the main part thereof. 5...Small sealed battery, 6...Battery case, 7
... Power generation element, 8 ... Current collection lead, 9 ... Sealing part, 10 ... Annular insulating isolation member made of ceramics, 11 ... Adhesive layer made of glass.

Claims (1)

[Claims] 1. An annular insulating isolation member made of ceramics is arranged in the annular gap between the battery case side and the metal current collector lead of the other electrode that penetrates the inside and outside of the metal battery case that also serves as the terminal of one electrode. A glass adhesive layer is interposed along the interface between the isolation member and the current collector lead and the interface with the battery case, and the adhesive layer connects the isolation member to the current collector lead and the battery case, respectively. A small sealed battery characterized in that the annular gap is sealed by tightly joining the battery.