JP2006179325A - Button-shape alkaline battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To curtail a hydrogen gas generating volume at over-discharge of a button-shape alkaline battery equipped with an anode containing zinc alloy not containing mercury and lead. <P>SOLUTION: The button-shape alkaline battery is provided with a cathode and a gel-like anode 9 containing zinc alloy not containing mercury and lead. The anode 9 contains at least a kind of an organic inhibitor selected from a group consisting of dimethyldithio carbamate, dipropyldithio carbamate, dibutyldithio carbamate, piperazinedithio carbamate, and Ni, N2, N3, N5-tetra (dithiocarboxy) tetraethylenepentamine salt. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a button-type alkaline battery.

  In conventional button-type alkaline batteries, zinc iodide alloy powder is used as the negative electrode active substance. Therefore, even if a three-layer clad material of Ni / SUS / Cu is used as the negative electrode container also serving as the negative electrode current collector, The presence of the Hg amalgam layer formed on the inner surface can prevent the formation of local cells of Zn and Cu, and can suppress the continuous generation of hydrogen gas.

  However, as a result of adopting zinc-free and lead-free zinc alloy powder as the negative electrode active material in consideration of environmental problems, Cu disposed on the inner surface of the negative electrode container forms a local battery with Zn in the negative electrode active material. As a result, the problem of generating hydrogen gas occurred. Manganese batteries and cylindrical alkaline manganese batteries have a cylindrical structure with voids in the batteries, so even if some hydrogen is generated, they are hardly affected, but button-type alkalis such as air zinc batteries and silver oxide batteries are not affected. The battery is button-shaped and has almost no air gap, and since it is small in size, if even a little hydrogen is generated, the can expands, and in extreme cases, the battery leaks, making it impossible to ensure battery safety over a long period of time.

  In order to solve this problem of hydrogen gas generation, the inner surface of the negative electrode container facing the negative electrode is made of a metal having a higher hydrogen overvoltage than Cu, such as Sn, Zn, and In. However, there was a new problem that the amount of hydrogen gas generated during overdischarge increased.

  In Patent Document 1, when a zinc-based alloy to which bismuth is added is used in a bottomed cylindrical alkaline battery and a compound that forms a complex by reacting with bismuth ions is added to the negative electrode, hydrogen gas during overdischarge is disclosed. It is disclosed that the generation amount can be suppressed.

However, although the complex described in Patent Document 1 is effective for bismuth elution from a zinc-based alloy, it is not effective for generating hydrogen gas due to the negative electrode container.
JP 2002-50349 A

  An object of the present invention is to reduce the amount of hydrogen gas generated at the time of overdischarge of a button-type alkaline battery having a negative electrode containing an anhydrous silver and lead-free zinc alloy.

A button-type alkaline battery according to the present invention is a button-type alkaline battery comprising a positive electrode, a gelled negative electrode containing an anhydrous silver and lead-free zinc alloy and an alkaline electrolyte,
The negative electrode is at least selected from the group consisting of dimethyldithiocarbamate, dipropyldithiocarbamate, dibutyldithiocarbamate, piperazinedithiocarbamate and N1, N2, N3, N5-tetra (dithiocarboxy) tetraethylenepentamine. It contains one type of organic inhibitor.

Further, according to the present invention, as one embodiment thereof, a positive electrode, a gelled negative electrode containing anhydrous silver and lead-free zinc alloy and an alkaline electrolyte, and a negative electrode serving also as a current collector of the gelled negative electrode A button-type alkaline battery comprising a container,
The negative electrode is at least selected from the group consisting of dimethyldithiocarbamate, dipropyldithiocarbamate, dibutyldithiocarbamate, piperazinedithiocarbamate and N1, N2, N3, N5-tetra (dithiocarboxy) tetraethylenepentamine. Contains one organic inhibitor,
Provided is a button-type alkaline battery in which at least one metal element selected from the group consisting of Sn, Zn and In is disposed on the inner surface of the negative electrode container facing the gelled negative electrode. .

  ADVANTAGE OF THE INVENTION According to this invention, it is possible to reduce the hydrogen gas generation amount at the time of the overdischarge of the button-type alkaline battery provided with the negative electrode containing an anhydrous silver and lead-free zinc alloy.

  As a result of intensive research, the inventors of the present invention include a gelled negative electrode containing an anhydrous silver and lead-free zinc alloy and an alkaline electrolyte, and a negative electrode container also serving as a negative electrode current collector of the gelled negative electrode. In the button-type alkaline battery, at least the inner surface of the negative electrode container facing the gelled negative electrode is formed of at least one metal element selected from the group consisting of Sn, Zn, and In, and dimethyldithiocarbamic acid is formed in the gelled negative electrode At least one organic inhibitor selected from the group consisting of a salt, dipropyldithiocarbamate, dibutyldithiocarbamate, piperazine dithiocarbamate and N1, N2, N3, N5-tetra (dithiocarboxy) tetraethylenepentamine By containing, while reducing the amount of hydrogen gas generated before use and during discharge interruption, Containing gas generation amount is was found to be reduced.

  That is, at least one metal element selected from the group consisting of Sn, Zn, and In disposed on the inner surface of the negative electrode container can suppress generation of hydrogen gas before use and when discharge is interrupted. When falling into an overdischarged state, not only the metal element disposed on the inner surface of the negative electrode container but also the internal substrate (for example, Cu layer) is eluted into the electrolyte. The organic inhibitors of the type described above can form a complex with ions of the metal (for example, Cu) that forms the base material, so that metal ions (for example, Cu ions) are not reprecipitated on the unreacted zinc alloy. The generation of hydrogen gas due to the formation of the local battery can be suppressed. As a result, it is possible to prevent problems such as total battery swelling during overdischarge and leakage due to an increase in internal pressure.

  Therefore, according to the present invention, generation of hydrogen gas inside the battery is reduced, and a high-performance, safe and environmentally friendly mercury-free and lead-free button alkaline battery can be provided.

  The organic inhibitor is preferably an alkali metal salt such as sodium salt or potassium salt. Among organic inhibitors, piperazine dithiocarbamate and N1, N2, N3, N5-tetra (dithiocarboxy) tetraethylenepentamine are preferred.

  Hereinafter, the gelled negative electrode and the negative electrode container will be described.

1) Gelled negative electrode The gelled negative electrode is, for example, at least one selected from the above-described types of anhydrous silver and lead-free zinc alloy powder, alkaline electrolyte, thickener (gelling agent), and the like. It is formed by mixing different types of organic inhibitors.

  The mercury-free and lead-free zinc alloy desirably contains at least one selected from the group consisting of aluminum, bismuth and indium. Among such anhydrous silver and lead-free zinc alloys, a zinc alloy having a Bi content of 50 to 1000 ppm, an In content of 100 to 1000 ppm, and at least one content selected from Al and Ca is 10 to 100 ppm Is preferred. A more preferable range of the Bi content is 100 to 500 ppm, a more preferable range of the In content is 300 to 700 ppm, and a more preferable range of at least one content selected from Al and Ca is 20 to 50 ppm.

  Mercury-free and lead-free zinc alloy has a gas generation rate of 90 (μL / g) from the lapse of 24 hours to 72 hours when 10 g of the powder is immersed in 10 g of a 33 wt% KOH aqueous solution and stored in a 60 ° C. atmosphere. -Day) It is desirable that it be below. As a result, the generation of hydrogen gas before use of the battery can be reduced, and a button-type alkaline battery having no problem of swelling or leakage can be obtained. Furthermore, it is desirable to employ anhydrous silver and lead-free zinc alloy powder having a gas generation rate of 30 (μL / g · day) or less.

  The content of the organic inhibitor in the gelled negative electrode is desirably 50 ppm or more and 5000 ppm or less with respect to the mass of the zinc alloy. This is due to the reason explained below. By setting the content of the organic inhibitor to 50 ppm or more, it is possible to sufficiently suppress changes in the total battery height after overdischarge. However, if the content of the organic inhibitor is more than 5000 ppm, a sufficient effect corresponding to the addition cannot be expected, and the internal resistance of the battery may be increased by an excessive organic inhibitor. Therefore, the content of the organic inhibitor is desirably 50 ppm or more and 5000 ppm or less. A more preferable range of the content of the organic inhibitor is 100 ppm or more and 2000 ppm or less.

  Examples of the alkaline electrolyte include an alkaline aqueous solution containing potassium hydroxide. The potassium hydroxide concentration in the alkaline electrolyte is preferably in the range of 30 to 45% by weight.

  As the thickening agent (gelling agent), those having a function of increasing the viscosity of the alkaline electrolyte to be gelled can be used. Examples of such a thickener include a water-absorbing polymer such as polyacrylic acid.

  In addition, it is desirable that the negative electrode contains at least one inorganic inhibitor selected from the group consisting of indium oxide, indium hydroxide, and bismuth oxide in an amount of 100 ppm to 1000 ppm with respect to the mass of the zinc alloy. Thereby, it is possible to suppress the generation of hydrogen gas when the battery is used and enter a pause state, and it is possible to obtain a button-type alkaline battery that is practically free from problems of swelling and leakage. A more preferable range of the content of the inorganic inhibitor is 200 ppm or more and 800 ppm or less.

2) Negative electrode container The negative electrode container is formed of a plate material in which a base material and a surface layer formed of at least one element selected from the group consisting of In, Sn, and Zn are laminated. It is located on at least the inner surface of the negative electrode container.

  The surface layer may be formed of a single metal of In, Sn, or Zn, or may be formed of an alloy containing these metals. Alternatively, a metal plate such as an In layer and a Sn layer, alloy layers, or a multilayer board in which a metal layer and an alloy layer are stacked may be used as the surface layer. Among these, a Sn metal layer and a Sn alloy layer are preferable. In this Sn alloy layer, the Sn content is 80% by mass or more, and the content of at least one additive metal element selected from the group consisting of Zn and In is 0.1% by mass or more and 20% by mass or less. It is desirable to make it. A more preferable range is an Sn content of 85% by mass or more and an additive metal element content of 5% by mass or more and 15% by mass or less.

  When the surface layer is formed by cladding, the thickness of the surface layer is preferably 3 μm or more and 40 μm or less. This is due to the reason explained below. If the thickness of the surface layer formed by the clad processing is less than 3 μm, the substrate may be exposed due to grain boundary corrosion even during overdischarge. On the other hand, if the thickness of the surface layer formed by the clad processing exceeds 40 μm, the sealing strength due to caulking and fixing may be reduced, and the occurrence of liquid leakage may be promoted. A more preferable range is 5 μm or more and 30 μm or less.

  When the surface layer is formed by plating such as electrolytic plating or electroless plating, the thickness of the surface layer is preferably 0.05 μm or more and 5 μm or less. This is due to the reason explained below. When the thickness of the surface layer formed by plating is less than 0.05 μm, the base material may be exposed due to elution into the electrolytic solution, and a negative electrode active substance and a local battery may be formed. On the other hand, when the thickness of the surface layer formed by plating exceeds 5 μm, the sealing strength due to caulking and fixing may be reduced, and the occurrence of liquid leakage may be promoted.

  As the base material, for example, a Ni / SUS / Cu three-layer clad plate material, Ni / SUS, etc., there is no particular limitation depending on the purpose of use, as long as there is no problem in electrical characteristics, strength, and appearance as a battery. It is not something. The Ni layer can be formed by clad processing or plating.

  The thickness of the substrate is desirably 50 μm or more and 150 μm or less. A more preferable range is 50 μm or more and 120 μm or less.

  For example, clad processing, electrolytic plating, electroless plating, or the like can be employed as a method for joining the base material and the surface layer. As the clad processing, a surface activated bonding method may be used.

  Here, the outline of the surface activated bonding method will be described. The surface to be a bonding surface of various plate materials having a predetermined thickness in a vacuum atmosphere is processed into a clean and active state by removing the oxide film on the surface by ion etching. In this method, the treated surfaces are joined under a low pressure at room temperature. In this manner, metals having greatly different melting points can be used as a clad material without heating as in the annealing process in order to remove work hardening.

  An embodiment according to the present invention will be described with reference to the drawings.

  FIG. 1 is a schematic cross-sectional view showing a zinc-air battery which is an embodiment of a button-type alkaline battery according to the present invention. FIG. 2 is an enlarged cross-sectional view of a main part of the air zinc battery of FIG.

  As shown in FIG. 1, the positive electrode container 1 having a bottomed cylindrical shape has an upper end 2 of an opening thereof bent inward by caulking. The positive electrode container 1 has an air hole 3 at the bottom. The positive electrode container 1 is formed of a metal such as stainless steel, for example, and also serves as a positive electrode terminal. A positive electrode catalyst layer 4 is accommodated in the positive electrode container 1. As the positive electrode catalyst contained in the positive electrode catalyst layer 4, for example, a mixture of activated carbon and a manganese oxide such as manganese dioxide can be used. The positive electrode catalyst layer 4 is obtained, for example, by mixing activated carbon, manganese oxide, expanded graphite as a conductive material, and polytetrafluoroethylene powder as a binder, and molding the sheet into a sheet shape.

  A diffusion paper 5 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 5, for example, craft paper can be used. The thickness of the diffusion paper 5 is desirably in the range of 50 to 100 μm. A water repellent film 6 having oxygen permeability is interposed between the diffusion paper 5 and the positive electrode catalyst layer 4. The water repellent film 6 is for preventing the alkaline electrolyte from leaking out from the air holes 3 of the positive electrode container 1. The water repellent film 6 can be formed from a fluororesin film such as a polytetrafluoroethylene film, for example. The water-repellent film 6 is not limited to a single sheet, and two or more sheets can be used in a stacked manner.

  The positive electrode current collector 7 is disposed on the positive electrode catalyst layer 4, and the peripheral edge thereof is in contact with the inner surface of the positive electrode container 1. Thereby, conduction between the positive electrode and the positive electrode container 1 is ensured. The positive electrode current collector 7 can be formed from, for example, a conductive porous plate such as a metal net.

  A separator 8 and a gelled negative electrode 9 are laminated on the positive electrode current collector 7 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 7. 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 container 10 serves as a negative electrode current collector and a negative electrode terminal. The negative electrode container 10 has a bottomed cylindrical shape and includes a reverse portion 11 that is folded back on the outer peripheral surface.

  The negative electrode container 10 is formed of a plate material in which a base material 13 and a surface layer 14 formed of at least one element selected from the group consisting of In, Sn, and Zn are laminated. It is located on the inner peripheral surface of the negative electrode container 10, the bottom surface 12 of the reverse portion 11, and the outer peripheral surface of the reverse portion 11.

  The negative electrode container 10 is formed by, for example, forming a plate material in which the base material 13 and the surface layer 14 are joined into a bottomed cylindrical shape by drawing so that the inner surface becomes the surface layer 14, and then opening the opening end on the outer peripheral surface. It is obtained by folding back to form the reverse portion 11. As a specific method for preparing the negative electrode container, the Cu surface of the Ni / SUS / Cu three-layer clad plate material is subjected to electrolytic plating and then formed by drawing or the like, or Ni / SUS / For example, a Sn foil is clad on a Cu or Ni / SUS plate, and then forming such as drawing is performed, but the manufacturing method is not particularly limited.

  Further, after forming the base material 13 into a bottomed cylindrical shape by drawing so that the Ni surface becomes the outer surface, the open end is folded back to the outer peripheral surface to form the reverse portion 11, and then the inner peripheral surface of the container Alternatively, the negative electrode container 10 may be obtained by forming the surface layer 14 on the bottom surface 12 and the outer peripheral surface of the reverse portion 11 by electroless plating. Specifically, the Ni / SUS / Cu three-layer clad plate material can be subjected to electroless plating on the Cu surface after forming such as drawing so that the Cu surface becomes the inner surface. The manufacturing method is not particularly limited.

  Such a negative electrode container 10 is arrange | positioned at the opening part of the positive electrode container 1, and functions as a sealing member. The outer peripheral surface of the reverse portion 11 of the negative electrode container 10 faces the inner peripheral surface near the opening of the positive electrode container 1.

  The ring-shaped insulating gasket 15 is interposed between the inner peripheral surface of the positive electrode container 1 and the negative electrode container 10 opposed thereto, and between the inner peripheral surface of the positive electrode container 1 and the outer peripheral surface of the gelled negative electrode 9. Yes. The insulating gasket 15 has an annular step 16 formed on the inner peripheral surface thereof, and the bottom surface 12 of the reverse portion 11 of the negative electrode container 10 is disposed on the step 16. The insulating gasket 15 is made of nylon, for example, and the surface thereof is coated with a polyamide-based resin. The insulating gasket 15 formed from such a material can improve alkali resistance.

  The air hole 3 of the positive electrode container 1 is temporarily blocked with a seal tape 17 attached to the bottom surface of the positive electrode container 1 in order to prevent useless discharge when not in use.

  According to the air zinc battery having the structure as described above, the inner peripheral surface of the negative electrode container 10, the bottom portion 12 and the outer peripheral surface of the reverse portion 11 are at least one kind of metal element selected from the group consisting of Sn, Zn, and In. Therefore, it is possible to suppress the formation of a local battery between the anhydrous silver-free lead-free negative electrode active substance and the negative electrode container 10 before use and when discharge is stopped. Can be suppressed.

  Further, in the case of overdischarge, not only the surface layer 14 of the negative electrode container 10 but also the base material 13 is eluted in the electrolytic solution, but dimethyldithiocarbamate, dipropyldithiocarbamate, dibutyldithiocarbamate, piperazine dithiocarbamine At least one organic inhibitor selected from the group consisting of acid salts and N1, N2, N3, N5-tetra (dithiocarboxy) tetraethylenepentamine salts includes ions of a metal (for example, Cu) forming the base material 13; Since a complex can be formed, reprecipitation of metal ions (for example, Cu ions) on an unreacted zinc alloy can be suppressed, and generation of hydrogen gas due to local battery formation can be suppressed. Therefore, it is possible to realize a button-type alkaline battery that suppresses generation of hydrogen gas during overdischarge as well as before use and when discharge is stopped.

  By setting the addition amount of the organic inhibitor to 50 ppm or more and 5000 ppm or less with respect to the mass of the zinc alloy, it is possible to further reduce the total battery swelling during overdischarge.

  Further, as a zinc alloy containing no silver and no lead, the gas generation rate from 90 hours to 72 hours after the passage of 24 hours when 10 g of the powder was immersed in 10 g of 33 wt% KOH aqueous solution and stored in a 60 ° C. atmosphere was 90 (μL / G · day), the leakage rate before use can be further reduced.

  Furthermore, the gel-like negative electrode 9 contains at least one inorganic inhibitor selected from the group consisting of indium oxide, indium hydroxide and bismuth oxide in an amount of 100 ppm or more and 1000 ppm or less with respect to the mass of the zinc alloy. The change in the total battery height due to the generation of hydrogen gas at the time of interruption can be further reduced.

  The present invention can be applied regardless of the type and size as long as it is a button-type battery using a negative electrode container that also serves as a current collector. For example, in FIG. 1 described above, an example in which oxygen is used as the positive electrode active material has been described. However, the present invention can be similarly applied to a button-type alkaline battery using manganese dioxide or silver oxide as the positive electrode active material.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the constituent elements without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of components disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

[Example]
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings described above.

Example 1
Mix 9.0 parts by weight of fine powder of polyacrylic acid as gelling agent with thickening action of electrolyte and 1.0 part by weight of indium oxide (In ₂ O ₃ ) as inorganic inhibitor until uniform. Stir. Next, 10 g of the zinc alloy powder in 10 g of an aqueous solution of 33 wt% KOH having an average particle size of 205 μm containing Bi of 127 ppm, In of 503 ppm and Al of 33 ppm and having a particle size of 75 μm to 300 μm accounted for 85% by weight or more. 200 parts by weight of anhydrous silver and lead-free zinc alloy powder having a gas generation rate of 87.5 (μL / g · day) after 24 hours to 72 hours when immersed in a 60 ° C. atmosphere And 52 parts by weight of an alkaline electrolyte composed of 30% KOH and 1% ZnO, 1.0 part by weight of the mixture of polyacrylic acid and indium oxide described above (indium oxide is 500 ppm based on the mass of the zinc alloy powder), 2 parts by weight of a solution containing 4% potassium piperazine dithiocarbamate as an organic inhibitor (based on the mass of the zinc alloy powder) Then, 400 ppm) was mixed and stirred to prepare a gelled zinc negative electrode.

  Also, a negative electrode container of a PR44 type zinc-air battery was fabricated by molding a three-layer clad material made of Ni / SUS304 / Cu having a thickness of 150 μm so that the Cu surface was the inner surface. The Cu surface of the negative electrode container was subjected to electroless substitution Sn plating to form a surface layer made of Sn metal having a thickness of 0.2 μm.

  An insulating gasket made of nylon and coated on the surface with a polyamide resin was prepared. This insulating gasket has a ring shape, and an annular step is provided on the inner peripheral surface thereof. The negative electrode container was inserted into the insulating gasket, and the bottom surface of the reverse part was arranged in a step so that the negative electrode container and the insulating gasket were integrated.

  The gel-like zinc negative electrode thus obtained is filled in a negative electrode container, and then fixed to the positive electrode container in which the positive electrode catalyst layer is accommodated by caulking, and the button-type zinc air battery of the JIS standard PR44 type having the structure shown in FIG. Manufactured.

  The gas generation rate of the zinc alloy powder was measured by the method described below. FIG. 3 is a schematic view showing a measuring device for measuring the gas generation rate of the zinc alloy.

  In a constant temperature water bath at 60 ° C., for example, 10 g of KOH 33 wt% aqueous solution 22 and 10 g of zinc alloy powder 23 are placed in an Erlenmeyer flask 21 having an internal volume of 25 mL, and then liquid paraffin 24 is filled into the Erlenmeyer flask. did. Next, the Erlenmeyer flask 21 was stoppered with a rubber stopper 26 into which the liquid paraffin moving tube 25 was inserted, and the lower end of the liquid paraffin moving tube 25 was inserted into the liquid paraffin 24.

  The liquid paraffin moving tube 25 was prepared by blocking the opening at the lower end of the 2.0 mL internal pipette and making a hole 27 in the side wall near the lower end.

  The gas generated by the reaction between the zinc alloy powder 23 and the KOH solution 22 accumulates in a space 28 located above the liquid paraffin 24 in the Erlenmeyer flask 21, and the liquid paraffin 24 corresponding to the volume of the generated gas moves to the liquid paraffin. It is pushed out from the hole 27 of the tube 25 and moves up in the moving tube 25. Read the scale of the moving tube 25 at a certain time and the scale after a certain time, and consider the volume change of the difference between these scales as the amount of gas generated, and divide this amount of gas generated by the elapsed time. To obtain the gas generation rate.

  For a while after the Erlenmeyer flask 21 is immersed in the thermostatic water tank, the liquid undergoes volume expansion due to temperature change, and the volume change does not occur due to gas generation. Therefore, when 24 hours have passed since the KOH 33 wt% aqueous solution 22 and the zinc alloy powder 23 were accommodated in the Erlenmeyer flask 21, the scale of the moving tube 25 was read, and after 48 hours later (KOH 33 wt% aqueous solution in the Erlenmeyer flask 21 No. 22 and the zinc alloy powder 23 are stored 72 hours after the storage), and the gas generation rate is calculated from the difference between the scales. The end of measurement is 72 hours later. The gas generation rate gradually decreases as the measurement time becomes longer, so it is clear that the measurement should be performed within the time showing the linear gas generation rate as much as possible. This is because it becomes possible.

(Example 2)
A button-type zinc-air battery having the same configuration as described in Example 1 was manufactured except that the type of the organic inhibitor was changed as shown in Table 1 below.

(Example 3)
Measured by the same method as described in Example 1 with a particle size distribution in which particles having a mean particle size of 201 μm containing Bi of 502 ppm, In of 503 ppm and Al of 30 ppm and a particle size of 75 μm to 300 μm account for 85% by weight or more. The button-type air zinc having the same structure as that described in Example 1 except that an anhydrous silver and lead-free zinc alloy powder having a gas generation rate of 15.3 (μL / g · day) is used. A battery was manufactured.

Example 4
The same zinc alloy powder as described in Example 3 was used, and 0.5 parts by weight of bismuth oxide (Bi ₂ O ₃ ) (250 ppm relative to the mass of the zinc alloy powder) and water were used as inorganic inhibitors. Except for using 0.5 parts by weight of indium oxide (In (OH) ₃ ) (250 ppm with respect to the mass of the zinc alloy powder), button-type air zinc having the same configuration as that described in Example 1 above. A battery was manufactured.

(Example 5)
Measured by the same method as described in Example 1 with a particle size distribution in which particles having a mean particle size of 198 μm and containing 75 μm to 300 μm of Bi containing 892 ppm Bi, 497 ppm In, and 32 ppm Al account for 85% by weight or more. The button-type air zinc having the same structure as that described in Example 1 except that an anhydrous silver and lead-free zinc alloy powder having a gas generation rate of 118.7 (μL / g · day) is used. A battery was manufactured.

(Example 6)
A button-type air zinc having the same structure as described in Example 1 above, except that 1 part by weight of a solution containing 4% potassium piperazine dithiocarbamate as an organic inhibitor (20 ppm relative to the mass of zinc powder) was used. A battery was manufactured.

(Example 7)
200 parts by weight of the same zinc alloy powder as described in Example 1, 52 parts by weight of an alkaline electrolyte composed of 30% KOH and 1% ZnO, 9 parts by weight of polyacrylic acid, and an organic inhibitor Except for preparing a gelled zinc negative electrode by mixing and stirring with 2 parts by weight of a solution containing 4% potassium piperazine dithiocarbamate (400 ppm with respect to the mass of zinc powder), as described in Example 1 above. A button-type zinc-air battery having the same configuration as that of the above was manufactured.

(Examples 8 to 10)
A button-type zinc-air battery having the same configuration as described in Example 1 was manufactured except that the type of the organic inhibitor was changed as shown in Table 1 below.

(Comparative example)
Mix and stir until 9.0 parts by weight of a fine powder of polyacrylic acid as a gelling agent having a thickening action for the electrolyte is uniformly 1.0 part by weight of indium oxide (In ₂ O ₃ ) as an inorganic inhibitor did. Next, a particle size distribution containing an average particle size of 205 μm and a particle size of 75 μm to 300 μm containing 127 ppm Bi, 503 ppm In, and 33 ppm Al accounts for 85% by weight or more, and the same method as described in Example 1 200 parts by weight of an anhydrous silver and lead-free zinc alloy powder having a gas generation rate measured in 87.5 (μL / g · day), 52 parts by weight of an alkaline electrolyte composed of 30% KOH and 1% ZnO, A gelatinous zinc negative electrode was prepared by mixing and stirring with 1.0 part by weight of the mixture of polyacrylic acid and indium oxide described above.

  A button-type zinc-air battery having the same configuration as described in Example 1 was produced except that this gelled zinc negative electrode was used.

About each PR44 form air zinc battery of Examples 1-10 and a comparative example, over discharge was performed for 120 hours after discharge characteristics (250 Ω constant resistance discharge / discharge capacity up to 1.0V, average value of n = 20). The battery total height change immediately after (n = 20 average value), the battery total height change after 2 weeks standing at room temperature (2W) at a discharge depth of 40% (n = 20 average value), 45 ° C. 93% RH 60 The number of leaks after storage for a day was investigated (n = 50). The results are shown in Table 1 below.

  As is apparent from Table 1, the group consisting of dimethyldithiocarbamate, dipropyldithiocarbamate, dibutyldithiocarbamate, piperazinedithiocarbamate and N1, N2, N3, N5-tetra (dithiocarboxy) tetraethylenepentamine The batteries of Examples 1 to 10 including the negative electrode containing at least one organic inhibitor selected from the above have a discharge capacity substantially equivalent to that of the battery of Comparative Example 1 in which these organic inhibitors are not added. It can be seen that the change in the total battery height immediately after 120 hours of overdischarge can be made small. Since the total battery height before discharge is about 5.2 mm, in Examples 1 to 4 and 7 to 10, the total battery height after overdischarge is below the JIS standard of PR44 of 5.4 mm. There are few practical problems.

  From a comparison between Example 1 and Example 5, in Example 1 in which a zinc alloy powder having a hydrogen gas generation rate of 90 (μL / g · day) or less was used as the negative electrode active substance, the battery was compared with Example 5. The total height change is small and the liquid leakage characteristics are excellent. This is presumably because the increase in the internal pressure of the battery due to the hydrogen gas generated during storage was suppressed. It seems that the storage leakage is self-dissolving rate of zinc alloy itself and the addition of inhibitors, but it is fundamental to long-term reliability to suppress self-dissolution of zinc alloy, that is, hydrogen gas generation as much as possible. This is clear and more preferably 30 (μL / g · day) or less.

  From comparison between Example 1 and Example 6, it can be understood that Example 1 in which the amount of the organic inhibitor added is in the range of 50 to 5000 ppm reduces the change in the total battery height after overdischarge. Although not described in the examples, when the addition amount of the organic inhibitor exceeds 5000 ppm, the remarkable effect is not seen so much, and considering the cost, 5000 ppm or less is appropriate.

  From the comparison between Example 1 and Example 7, in the battery of Example 1 including the negative electrode containing an inorganic inhibitor such as indium oxide, the total battery height when the discharge depth is stopped at 40% and the battery is left to stand is small. Thus, the effect of suppressing the generation of hydrogen gas by adding an inorganic inhibitor is clear. Further, if the addition amount is 100 ppm or less, the effect may not be sufficient, and if it exceeds 1000 ppm, a remarkable effect is not seen so much, and considering performance and cost, 100 to 1000 ppm is desirable.

  As described above, according to the present invention, hydrogen gas generation inside the battery is suppressed over a long period of time while being a negative electrode containing anhydrous silver and no lead-added zinc alloy powder. It is possible to provide a safe, environmentally friendly, high-performance button-type alkaline battery that is free from problems.

  In the above-described embodiments, examples of button-type zinc-air batteries have been described. However, the present invention is not limited to the above-described embodiments, and can take various forms without departing from the spirit of the invention. . For example, it is possible to use a coin shape, a flat shape in which the shape of the main surface is a square or a substantially square.

FIG. 1 is a schematic cross-sectional view showing a zinc-air battery as an embodiment of a button-type alkaline battery according to the present invention. The principal part expanded sectional view of the air zinc battery of FIG. The schematic diagram which shows the measuring apparatus for measuring the gas generation rate of a zinc alloy.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Positive electrode container, 2 ... Upper end of opening, 3 ... Air hole, 4 ... Positive electrode catalyst layer, 5 ... Air diffusion paper, 6 ... Water-repellent film, 7 ... Positive electrode collector, 8 ... Separator, 9 ... Gel-like Zinc negative electrode, 10 ... negative electrode container, 11 ... reverse part, 12 ... bottom of reverse part (end face of opening of negative electrode container), 13 ... base material, 14 ... surface layer, 15 ... insulating gasket, 16 ... step, 17 DESCRIPTION OF SYMBOLS ... Seal tape, 21 ... Erlenmeyer flask, 22 ... KOH 33 weight% aqueous solution, 23 ... Zinc alloy powder, 24 ... Liquid paraffin, 25 ... Liquid paraffin transfer pipe, 26 ... Rubber stopper, 27 ... Hole, 28 ... Gas accommodation space.

Claims (4)

A button type alkaline battery comprising a positive electrode, a gelled negative electrode containing an anhydrous silver and lead-free zinc alloy and an alkaline electrolyte,
The negative electrode is at least selected from the group consisting of dimethyldithiocarbamate, dipropyldithiocarbamate, dibutyldithiocarbamate, piperazinedithiocarbamate and N1, N2, N3, N5-tetra (dithiocarboxy) tetraethylenepentamine. A button-type alkaline battery comprising one type of organic inhibitor.   2. The button-type alkaline battery according to claim 1, wherein the at least one organic inhibitor is 50 ppm or more and 5000 ppm or less with respect to the mass of the zinc alloy.   The zinc alloy has a gas generation rate of 90 (μL / g · day) or less after 24 hours to 72 hours when 10 g of the powder is immersed in 10 g of 33 wt% KOH aqueous solution and stored in an atmosphere of 60 ° C. The button-type alkaline battery according to claim 1 or 2.   The negative electrode contains at least one inorganic inhibitor selected from the group consisting of indium oxide, indium hydroxide, and bismuth oxide in a range of 100 ppm to 1000 ppm with respect to the mass of the zinc alloy. The button-type alkaline battery according to any one of 1 to 3.

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