JP2007048660A - Button type battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a button type battery improving fitting capability of a positive case and a negative case and enhancing electrolyte leakage resistant characteristics. <P>SOLUTION: The button type battery is equipped with the positive case 1 and the negative case 10, a gelled negative electrode 9 coming in contact with the inner surface of the negative case 10, an insulating gasket 12 interposed between the positive case 1 and the negative case 10, and a silicone system resin layer 13 of 0.0018-0.0355 mg/cm<SP>2</SP>formed on the surface of the insulating gasket 12. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a button type battery.

  Examples of button type batteries include alkaline button batteries using zinc powder for the negative electrode and manganese dioxide for the positive electrode, silver oxide batteries using silver oxide for the positive electrode, and air batteries using oxygen in the air for the positive electrode active substance. Are known. These are used in small electronic devices, watches, hearing aids, and the like.

  A configuration example of the air battery will be described below. Diffusion paper, a water-repellent film, an air electrode, and a separator are accommodated in an upper portion inside a positive electrode case having a step portion on the bottom surface having air holes. The air electrode includes a nickel-plated stainless steel-made positive electrode current collector and a positive electrode catalyst layer integrated with the positive electrode current collector. The positive electrode catalyst layer is produced, for example, by press-fitting a positive electrode current collector made of activated carbon, Teflon (registered trademark), a conductive agent and a cocatalyst onto a positive electrode current collector. On the top of the separator is a negative electrode case molded from a base material such as a nickel-stainless-copper three-layer clad material or a nickel-stainless-copper three-layer clad material plated with tin on an insulating packing. Be placed. The insulating packing is made of, for example, a synthetic resin, and a sealing agent such as a polyamide resin is applied to the surface of the insulating packing to prevent leakage of the alkaline electrolyte. Further, the negative electrode case is filled with a gelled negative electrode containing a negative electrode active substance and an alkaline electrolyte. The gelled negative electrode and the air electrode face each other with a separator interposed therebetween.

  In order to suppress leakage of the alkaline electrolyte in the button type battery, a crimped structure such as a crimp type is used and a sealing agent is applied to a packing made of a synthetic resin. At this time, if the application amount of the sealing agent is excessive, the fitting property between the negative electrode case and the positive electrode case is lowered. When crimping is performed in a state where the fitting property is lowered and the negative electrode case is not sufficiently fitted into the positive electrode case, the gelled negative electrode oozes out from the inside of the battery.

  It has been found that the problem of this seeping out is that the packing surface becomes non-uniform due to an excessive amount of sealant. Regarding the method for improving the non-uniformity of the sealant, the sealant solution is sprayed while flowing the packing, and at the same time, the air is aerated and the sealant is dried and solidified on the packing surface by uniformly spraying the sealant on the packing surface. It became possible to eliminate an excessive sealing agent by applying the agent (Patent Document 1).

  However, since the amount of hydrogen gas generated from the air battery tends to increase due to the recent demand for dehydration, the air battery is required to further improve the leakage characteristics.

  In Patent Document 2, a sealing agent is applied to the entire surface of an insulating gasket of a button-type alkaline battery, and a powdery sliding agent such as carbon black, graphite, silica, talc, or mica is dispersed in a solvent on the surface of the sealing agent. Application.

  However, since the slip agent described in Patent Document 2 has a large solid content, the solid content tends to adhere to the packing surface, which causes a decrease in liquid leakage characteristics. Furthermore, since it is necessary to apply the slipping agent while stirring to prevent the solids from settling, the amount of the slip agent applied tends to be biased, and the fitting property between the positive electrode case and the negative electrode case decreases due to the unevenness of the packing surface, The gelled negative electrode sometimes oozes out from the battery assembly.

  Further, in Patent Document 3, in an alkaline battery in which a metal sealing plate also serving as a negative electrode terminal is sealed by caulking an opening of a positive electrode case inward through an insulating gasket, a portion of the insulating gasket exposed on the battery surface It is disclosed to apply silicone or dry and solidify after application.

According to the alkaline battery described in Patent Document 3, although the deterioration of the creep characteristics of the insulating gasket due to water absorption from the outside is suppressed, it is easy to cause poor fitting in which the negative electrode case is not sufficiently fitted into the positive electrode case.
JP-A-10-223184 JP-A-8-315792 JP-A-6-20664

  An object of the present invention is to provide a button type battery in which the fitting property between the positive electrode case and the negative electrode case is improved and the liquid leakage resistance is excellent.

A button type battery according to the present invention comprises a positive electrode case,
A negative electrode case;
A gelled negative electrode in contact with the inner surface of the negative electrode case;
Insulating packing interposed between the positive electrode case and the negative electrode case;
It is formed on the surface of the insulating packing, and comprises a silicone resin layer of 0.0018 mg / cm ² or more and 0.0355 mg / cm ² or less.

  ADVANTAGE OF THE INVENTION According to this invention, the fitting property of a positive electrode case and a negative electrode case is improved, and the button type battery excellent in the leak-proof characteristic can be provided.

  The inventors of the present invention examined a slip agent that has almost no solid content and does not require stirring when applied to the surface of the insulating packing. As a result of repeated studies on a slip agent having excellent dispersion stability of a solution, it was found that a silicone resin is good. Thereby, a silicone type resin layer can be uniformly formed on the insulating packing surface.

Furthermore, by making the amount of the silicone resin layer formed per 1 cm ^{2 of} the insulating packing surface area 0.0018 mg or more and 0.0355 mg or less, the fitting property between the positive electrode case and the negative electrode case can be improved. From this, it was found that the gelled negative electrode was prevented from seeping out and the reliability of the button type battery was improved. According to the button type battery having improved fitting properties and leak-proof characteristics, the leak rate when hydrogen gas is generated can be lowered.

If the amount of the silicone-based resin layer formed is less than 0.0018 mg / cm ² , the effect of the silicone-based resin layer as a slip agent is small, and the unevenness on the surface of the insulating packing is large, so that the fitting failure cannot be improved. Many leaks occur from the beginning of assembly. On the other hand, if the amount of the silicone-based resin layer formed exceeds 0.0355 mg / cm ² , the packing surface can be smoothed, but the packing surface softens, resulting in increased fitting failure, and leakage from the beginning of assembly. Will increase. A more preferable range of the formation amount of the silicone-based resin layer is 0.0018 mg / cm ² or more and 0.0177 mg / cm ² or less, and a more preferable range is 0.0035 mg / cm ² or more and 0.0142 mg / cm ^2. It is as follows.

  The silicone resin is preferably a liquid resin having excellent solubility or dispersibility in both an organic solvent and water. For example, silicone oils such as dimethyl silicone are liquid and are soluble in both organic solvents and water. Moreover, polyalkylsiloxane etc. can also be used as a silicone resin.

  The silicone resin layer as the slip agent layer can be obtained by, for example, applying a slip agent solution containing a silicone resin and a solvent to the surface of the insulating packing by spraying and drying. The slip agent solution is allowed to contain a preservative.

  The solvent used for the slip agent solution is not particularly limited as long as the drying property of the slip agent solution becomes high. As the solvent, for example, water, an organic solvent, a mixed solution of water and an organic solvent, or the like can be used. When an alcohol-based organic solvent or an ether-based organic solvent is used, a slip agent solution in the form of an emulsion solution can be obtained. Examples of the ether organic solvent include phenyl ether. These organic solvents can be used alone or in combination of two or more. As the emulsion solution of dimethyl silicone oil, for example, trade names TSM630, TSM631, and TSM632 manufactured by GE Toshiba Silicone Co., Ltd. can be used.

The concentration of the silicone resin in the slip agent solution is preferably 0.5% by weight or more and 2% by weight or less. When the concentration is less than 0.5% by weight, the coating amount must be increased in order to make the formation amount of the silicone resin layer 0.0018 mg / cm ² or more and 0.0355 mg / cm ² or less. There is a risk of unevenness on the surface. On the other hand, when the concentration exceeds 2% by weight, the coating amount must be extremely reduced in order to make the formation amount of the silicone resin layer 0.0018 mg / cm ² or more and 0.0355 mg / cm ² or less, Distribution of silicone resin layer tends to be non-uniform.

  The insulating packing can be formed from, for example, nylon resin. A sealant needs to be applied to the surface of the insulating packing. In order to improve the leakage resistance, it is desirable that a sealing agent is formed on the surface of the insulating packing. Examples of the sealing agent include polyamide resins such as aliphatic polyamides.

  The negative electrode case also serves as a current collector for the gelled negative electrode. As the negative electrode case, for example, a nickel-stainless-copper three-layer clad material or a base material obtained by tin plating the copper surface of the three-layer clad material can be used. The nickel layer of the cladding material can be changed to a nickel alloy layer. Moreover, you may use a copper alloy layer instead of a copper layer.

  The gelled negative electrode is accommodated in the battery so as to be in contact with the inner surface of the negative electrode case. The gelled negative electrode includes a negative electrode active substance and an alkaline electrolyte.

  As the negative electrode active substance, for example, zinc is desirable because it is inexpensive, but not limited to this, other metals can also be used. Further, it is preferable to include at least one element selected from the group consisting of In, Bi, Ga, Pb, Sn, Cd, Al, and Co, and to form a zinc alloy, because generation of hydrogen gas is suppressed.

  Examples of the alkaline electrolyte include an alkaline aqueous solution containing potassium hydroxide and zinc oxide.

  A thickener having a function of increasing the viscosity of the alkaline electrolyte and causing it to gel can be added to the gelled negative electrode. Examples of such a thickener include a water-absorbing polymer such as polyacrylic acid.

  It is desirable to add an inhibitor for suppressing the generation of hydrogen gas to the gelled negative electrode. Examples of the inhibitor include compounds such as indium oxide, indium hydroxide, and bismuth oxide. By using such a compound, the generation of hydrogen gas in a discharge resting state can be further suppressed.

  The positive electrode case also serves as a positive electrode terminal. The positive electrode case can be formed of a metal such as stainless steel, for example. Moreover, as an active substance of a positive electrode, it is possible to use oxygen, manganese dioxide, silver oxide, etc., for example.

  Hereinafter, a button type air battery according to an embodiment of the present invention will be described with reference to FIGS.

  FIG. 1 is a schematic cross-sectional view showing an embodiment of a button type air battery which is an example of the present invention, and FIG. 2 is an enlarged cross-sectional view of a main part of the air battery of FIG.

  As shown in FIG. 1, a positive electrode case 1 having a bottomed cylindrical shape has an upper end 2 of an opening thereof bent inward by caulking. The positive electrode case 1 has an air hole 3 at the bottom. The positive electrode case 1 is made of a metal such as stainless steel and serves also as a positive electrode terminal. In the positive electrode case 1, a positive electrode using oxygen as a positive electrode active material is accommodated. The positive electrode includes the positive electrode catalyst layer 4. The positive electrode catalyst layer 4 is obtained, for example, by mixing activated carbon, manganese oxide (for example, manganese dioxide) as a promoter, expanded graphite as a conductive material, and polytetrafluoroethylene powder as a binder. The obtained mixture is obtained by pressure-filling the positive electrode current collector 5. As the positive electrode current collector 5, for example, a nickel-plated stainless steel net can be used.

  A diffusion paper 6 for uniformly diffusing air into the positive electrode catalyst layer 4 is disposed on the bottom inner surface of the positive electrode container 1. For the diffusion paper 6, for example, kraft paper can be used. The thickness of the diffusion paper 6 is desirably in the range of 50 to 100 μm. A water repellent film 7 having oxygen permeability is interposed between the diffusion paper 6 and the positive electrode catalyst layer 4. The water repellent film 7 is for preventing the alkaline electrolyte from leaking out from the air holes 3 of the positive electrode container 1. The water repellent film 7 can be formed from, for example, a fluororesin film such as a polytetrafluoroethylene film. Note that the water repellent film 7 is not limited to a single sheet, and two or more sheets can be used.

  A separator 8 and a gelled negative electrode 9 are laminated on the positive electrode current collector 5 in this order. The separator 8 is formed of, for example, a microporous membrane made of polyolefin such as polypropylene and a nonwoven fabric. The microporous membrane is opposed to the negative electrode 9, and the nonwoven fabric is opposed to the positive electrode current collector 5. The microporous film is for preventing an internal short circuit due to precipitation of zinc oxide. It is mainly the nonwoven fabric that contributes to the retention of the alkaline electrolyte.

  The negative electrode case 10 also serves as a negative electrode current collector, has a bottomed cylindrical shape, and has a reverse portion 11 whose opening end is folded outward. The negative electrode case 10 is inserted into the opening of the positive electrode case 1 so that the inner surface thereof is in contact with the negative electrode 9 and the reverse portion 11 is surrounded by the bent opening end 2 of the positive electrode case 1. The ring-shaped insulating packing 12 has a step 12a on its inner surface. The reverse portion 11 of the negative electrode case 10 is fitted to the step 12 a of the insulating packing 12. The silicone resin layer (slip agent film) 13 is formed on the surface of the insulating packing 12. The negative electrode case 10 is caulked and fixed to the positive electrode case 1 via the insulating packing 12.

  As shown in FIG. 2, the negative electrode case 10 is formed by drawing a three-layer clad material composed of, for example, a nickel layer 14, a stainless steel layer 15, and a copper layer 16 so that the inner surface becomes the copper layer 16. After forming into a bottomed cylindrical shape, it is obtained by forming the reverse part 11 by folding back the opening end.

  By the way, the air hole 3 of the positive electrode case 1 is temporarily closed with a seal tape 17 attached to the bottom surface of the positive electrode case 1 in order to prevent useless discharge when not in use.

  1 and 2 exemplify a button type air battery, the present invention is not limited to this, and can be applied to other battery systems such as an alkaline button battery and a silver oxide battery.

[Example]
Hereinafter, the present invention will be described by way of examples.

Example 1
<Formation of slip agent film (silicone resin layer)>
10,000 PR44 type nylon insulating packings coated with a sealing agent made of polyamide resin were prepared. As a slip agent solution, an emulsion solution (including dimethyl silicone oil, polyalkylsiloxane, phenyl ether, preservative, and water) of a trade name TSM630 manufactured by GE Toshiba Silicone Co., Ltd. is set so that the concentration of the silicone resin becomes 1% by weight. The one diluted with water was used.

The above-mentioned 10,000 insulating packings were sprayed with 5 g of a slip agent solution and dried to form a slip agent film on the surface of the insulating packing. From the spray amount of the slip agent solution and the concentration of the silicone resin in the slip agent solution, the actual application amount (actual slip agent amount) of the silicone resin for 10,000 insulating packings is calculated, and the result is shown in the following table. It is shown in 1. Table 1 also shows the spray amount of the slip agent solution and the formation amount of the slip agent film (silicone resin layer). The total surface area of 10,000 insulating packings used was 28200 cm ² .

<Assembly of button type air battery>
Diffusion paper, a water repellent film, a positive electrode catalyst layer, a positive electrode current collector, and a separator were housed in the upper part inside the positive electrode case having a stepped portion on the bottom surface having air holes. The positive electrode catalyst layer and the positive electrode current collector are filled with a positive electrode catalyst powder made of activated carbon, polytetrafluoroethylene, manganese dioxide, and expanded graphite into a nickel-plated stainless steel net (positive electrode current collector). The integrated one was used. The negative electrode case material is a negative electrode case molded from a base material with a nickel-stainless-copper three-layer clad material plated with tin, and fitted with an insulating packing with a lubricant film as described above. I let you.

On the other hand, indium oxide (In ₂ O ₃ ) was mixed and stirred in a fine powder of polyacrylic acid. Next, a zinc alloy powder containing In, Bi and Al was mixed and stirred with an alkaline electrolyte composed of KOH and ZnO and the mixture of polyacrylic acid and indium oxide to prepare a gelled zinc negative electrode.

  After the obtained gelled negative electrode is housed in the negative electrode case, the negative electrode case is fitted into the positive electrode case and fixed by caulking, thereby assembling the PR44 type button type air cell having the structure shown in FIG. It was.

(Examples 2 to 6)
A button-type air battery as in Example 1 except that the amount of the slip agent film (silicone resin layer) formed is adjusted as shown in Table 1 below by adjusting the spray amount of the slip agent solution. Assembled.

(Comparative Example 1)
Using a silicone resin with the trade name TSF451 manufactured by GE Toshiba Silicone Co., Ltd. (in liquid form, the main component is dimethylsilicone oil and does not contain organic solvent and water), the spray amount, the actual silicone resin A button type air battery was assembled in the same manner as in Example 1 except that the coating amount and the formation amount of the slip agent film (silicone resin layer) were changed as shown in Table 1 below.

(Comparative Example 2)
A button type air battery was assembled in the same manner as in Example 1 except that the slip film was not formed on the insulating packing.

(Comparative Example 3)
The insulating packing coated with the sealing agent in the same manner as in Example 1 was sprayed with a slipping agent solution containing 5% by weight of talc as a slipping agent, the balance being 45% by weight of isopropyl alcohol and 50% by weight of ethyl alcohol, and dried. By doing so, a slip agent film was formed on the surface of the insulating packing. At this time, since talc easily settles in the solution, the slipping agent solution was sprayed with stirring. The amount of slip agent film per 1 cm ^{2 of the} insulating packing surface area is shown in Table 1 below.

<Evaluation of fitability>
About 10,000 button type batteries of Examples 1-6 and Comparative Examples 1-3, the fitting property of the positive electrode case and the negative electrode case in the battery assembly process was investigated. A case where the positive electrode case was not fitted into a predetermined position of the negative electrode case was regarded as a fitting failure, and the fitting failure rate is shown in Table 1 below in ppm.

<Evaluation of seepage defects>
For each of 10,000 button-type batteries of Examples 1 to 6 and Comparative Examples 1 to 3, the number of occurrences of gel seepage during battery assembly was investigated, and the gel seepage occurrence rate is shown in Table 1 below in ppm.

As is clear from Table 1, the button type of Examples 1 to 6 in which a silicone resin layer (slip agent film) of 0.0018 mg / cm ² or more and 0.0355 mg / cm ² or less was formed on the surface of the insulating packing. In batteries, there are few defects due to poor fitting and gel seepage. This is due to the fact that the fitting property is improved by reducing the irregularities on the packing surface. Even when the slip agent was sprayed, the effect of the sealing agent on the packing surface was not lost, and the gel exudation failure was also reduced. This is considered to be a synergistic effect with the sealing agent due to a decrease in poor fitting. In particular, in the button type batteries of Examples 1 to 4 having a slip agent film amount in the range of 0.0018 to 0.0177 mg / cm < ² >, the seepage failure rate was very low at 1 ppm or less. Furthermore, the button type batteries of Examples 2 and 3 having a slip agent coating amount in the range of 0.0035 to 0.0142 mg / cm ² not only had no seepage failure but also had very poor fitting properties. There were few.

On the other hand, according to Comparative Example 1 in which the liquid silicone-based resin was applied as it is as in Patent Document 3 described above, the amount of the slip agent film exceeded 0.0355 mg / cm ² , but the irregularities on the packing surface disappeared. Defects due to gel exudation tend to be high. This is considered to be because the amount of slip agent per surface area was too large, and the surface of the packing was too smooth and the gel was likely to ooze out. Moreover, according to the comparative example 2 whose slip agent film | membrane amount is less than 0.0018 mg / cm < ² >, a fitting defect becomes high a little. In the button type battery of Comparative Example 3 using a powdery slip agent as in Patent Document 2 described above, poor fitting was high. This is considered that although the slip agent solution was sprayed while stirring, talc was unevenly distributed and solidified on the surface of the insulating packing, and thus the fitting property was deteriorated.

From these results, it is understood that by forming a silicone resin layer of 0.0018 mg / cm ² or more and 0.0355 mg / cm ² or less on the packing surface, poor fitting and poor gel seepage during assembly are reduced. It was. Furthermore, regardless of the battery structure, a similar ring-shaped packing can provide a highly reliable battery.

The typical sectional view showing one embodiment of the button type air battery which is an example of the present invention. The expanded sectional view of the principal part of the air battery of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Positive electrode case, 2 ... Upper end of opening, 3 ... Air hole, 4 ... Positive electrode catalyst layer, 5 ... Positive electrode collector, 6 ... Air diffusion paper, 7 ... Water-repellent film, 8 ... Separator, 9 ... Gel-like Negative electrode, 10 ... negative electrode case, 11 ... reverse part, 12 ... insulating packing, 12a ... step, 13 ... slip agent film (silicone resin layer), 14 ... nickel layer, 15 ... stainless steel layer, 16 ... copper layer, 17 ... sealing tape.

Claims (3)

A positive electrode case;
A negative electrode case;
A gelled negative electrode in contact with the inner surface of the negative electrode case;
Insulating packing interposed between the positive electrode case and the negative electrode case;
A button-type battery comprising: a silicone-based resin layer formed on a surface of the insulating packing and having a thickness of 0.0018 mg / cm ² or more and 0.0355 mg / cm ² or less.   The button type battery according to claim 1, wherein the silicone resin layer is obtained by applying a solution of a silicone resin having a concentration of 0.5 wt% or more and 2 wt% or less and drying the solution.   3. The button type battery according to claim 1, wherein the silicone resin is dimethyl silicone.

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