JP2018037369A - Air battery and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air battery excellent in load characteristics and liquid leakage resistance, and a method of manufacturing the same.SOLUTION: In an air battery of the present invention, an air diffusion membrane, a water-repellent membrane, a positive electrode body and a separator are accommodated, in order, from a bottom side of a positive electrode case, in a battery case comprising the positive electrode case having an air hole, a negative electrode case, and a resin gasket. A negative electrode is accommodated between the separator and the negative electrode case. The positive electrode body has a bending strength of 3.15 N/cm or less.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an air battery having excellent leakage resistance and improved load characteristics, and a manufacturing method thereof.

  An air battery having a positive electrode made of an air electrode using manganese dioxide or the like as a catalyst and a negative electrode using metal particles such as zinc particles such as zinc particles or zinc alloy particles as an active material is oxygen in the air as a positive electrode active material. In order to use, an air hole for taking in air is provided in the exterior body (battery case), but there is a concern that the electrolyte solution leaks out from the air hole depending on the internal configuration of the battery and the usage state of the battery.

That is, since the volume of the negative electrode expands due to the discharge reaction of zinc of the negative electrode shown below, as the discharge proceeds, the electrolyte is pushed out by the expanded negative electrode and easily leaks from the air holes. Become.
Zn + 2OH ⁻ → ZnO + H ₂ O + 2e ⁻

  In order to prevent the above problem, it is a general battery configuration that the bottom surface side of the sealing plate (negative electrode case) containing the negative electrode is not filled with the negative electrode material, and the empty space functions as a buffer against the expansion of the negative electrode material. Therefore, the filling rate of the negative electrode material with respect to the internal volume on the negative electrode side is set to a certain value or less (Patent Documents 1 and 2).

  On the other hand, when the battery is sealed by crimping the periphery of the outer can, the center of the positive electrode may bend and warp to the negative electrode side due to the pressure, and the adhesion between the positive electrode and the separator or the water repellent film When the performance deteriorates, problems such as a decrease in load characteristics and a decrease in leakage resistance due to a non-uniform sealing shape are likely to occur.

For the above problem, the height of the air diffusion chamber in the outer can is set to 50% or more of the total thickness of the separator, the air electrode, and the water repellent film, or the core material for the current collector as, by configuring the positive electrode with a tensile strength of 580N / mm ² or more 1000 N / mm ² knitting following linear core network or expanded metal, it has been proposed to prevent the curvature of the positive electrode that occurs during sealing (Patent Documents 3 and 4).

JP-A-2-262281 Japanese Patent Laid-Open No. 11-73949 Japanese Patent Laid-Open No. 11-54160 JP 2009-146846 A

  However, as described in Patent Documents 1 and 2, the method of providing a space more than a certain amount without filling the negative electrode material on the bottom surface side of the negative electrode case results in insufficient electrical conduction between the negative electrode material and the negative electrode case. As a result, the utilization factor of the negative electrode material decreases, and the capacity of the battery tends to decrease.

  Further, as described in Patent Documents 3 and 4, even if the positive electrode can be prevented from being bent at the time of sealing, if the positive electrode cannot be flexibly deformed in response to the pressure from the expanding negative electrode, The progress of the discharge reaction is hindered, and again, problems such as deterioration of load characteristics and leakage resistance are likely to occur.

  This invention is made | formed in view of the said situation, The objective is to provide the air battery excellent in load characteristics and liquid leakage resistance, and its manufacturing method.

  The air battery of the present invention that has achieved the above object has an air diffusion film, a water repellent film, a positive electrode body and a separator in a battery case comprising a positive electrode case having air holes, a negative electrode case, and a resin gasket. The positive electrode case is accommodated in order from the bottom side, the negative electrode is accommodated between the separator and the negative electrode case, and the positive electrode body has a bending strength of 3.15 N / cm or less. It is characterized by this.

  Moreover, the manufacturing method of the air battery of the present invention is a method of manufacturing the air battery of the present invention, wherein the positive electrode body includes a catalyst layer and a current collector having a bending strength of 3.2 N / cm or less. It is characterized by using.

  According to the present invention, it is possible to provide an air battery excellent in load characteristics and liquid leakage resistance, and a manufacturing method thereof.

It is a longitudinal section showing an example of an air battery of the present invention typically. It is explanatory drawing of the measuring method of the bending strength of the positive electrode body which concerns on an air battery.

  A longitudinal sectional view schematically showing an example of the air battery of the present invention is shown in FIG. An air battery 1 shown in FIG. 1 includes a negative electrode case 3 in which a negative electrode 5 is embedded in an opening of a positive electrode case 2 in which a positive electrode body (air electrode) 4 and a separator 6 are embedded. The open end portion of the positive electrode case 2 is tightened inwardly, and the resin gasket 10 contacts the negative electrode case 3 so that the open portion of the positive electrode case 2 is sealed. Has been. That is, in the air battery shown in FIG. 1, a power generation element including the positive electrode body 4, the negative electrode 5, and the separator 6 is loaded in a space in the battery case including the positive electrode case 2, the negative electrode case 3, and the resin gasket 10. Further, an electrolytic solution is injected and held in the separator. The positive electrode case 2 also serves as a positive electrode terminal, and the negative electrode case 3 also serves as a negative electrode terminal and a negative electrode current collector.

  The positive electrode case 2 is provided with an air hole 9 for taking air into the battery case. Further, the positive electrode case 2 is provided with a step at the bottom (lower side in the figure), and an air diffusion film 7 for diffusing the air taken into the battery case from the air holes 9 into the lower part of the bottom step. Is arranged. The upper part of the bottom step of the positive electrode case 2 supplies air (oxygen) diffused by the air diffusion film 7 to the positive electrode body 4 and prevents leakage of the electrolyte in the battery from the air holes 9. A water repellent film 8 is disposed, and a positive electrode body 4 and a separator 6 are overlaid on the water repellent film 8.

  In FIG. 1, the positive electrode body 4 has a mountain shape in side view with the apex around the center of the battery due to the pressure at the time of sealing, and the separator 6 and the water repellent film 8 also follow the positive electrode body. 4, the positive electrode body 4 has a flat plate shape as shown in Patent Document 3, for example, and a gap is formed between the water repellent film 8 and the bottom inner surface of the positive electrode case 2. It may be a form. However, when the positive electrode body has a mountain shape as viewed from the side as shown in FIG. 1, the surface area increases compared to, for example, a flat plate shape, and it is easier to come into contact with air. It is preferable because the characteristics are further improved.

  In the air battery of the present invention, a positive electrode body having a low bending strength is used. When the metal particles in the negative electrode expand with the discharge of the battery, the surface on the separator side of the positive electrode body is subjected to stress toward the bottom side of the positive electrode case, but in the battery of the present invention, the bending strength of the positive electrode body is small, The positive electrode body can be flexibly deformed according to the expansion of the negative electrode. As a result, even if the discharge reaction proceeds, the positive electrode body is not easily cracked, and the adhesion to the negative electrode and the separator and the adhesion to the gasket are easily maintained, thereby preventing leakage (leakage of electrolyte). In addition, excellent load characteristics can be maintained.

  The positive electrode body according to the air battery of the present invention has a bending strength of 3.15 N / cm or less, preferably 2.5 N / cm or less.

  However, if the bending strength of the positive electrode body is too small, the handleability of the positive electrode body may be lowered. Therefore, the bending strength of the positive electrode body is preferably 0.5 N / cm or more.

  The bending strength of the positive electrode body referred to in this specification can be determined by the following method.

<Measurement of bending strength of positive electrode body>
In the present invention, the shape of the positive electrode body when measuring the bending strength is circular, and in the case of other shapes, the measurement is performed by the following procedure after punching out into a circular shape.

  As shown in FIG. 2A, two metal rods (made of stainless steel) 11 and 11 having a diameter of 4 mm are prepared, and the distance between these metal rods 11 and 11 (distance between fulcrums: Lv) is positive electrode body. The metal rods 11 and 11 are arranged in parallel so as to satisfy the following general formula (1) with respect to the diameter: W (mm).

  Lv = 8 × W / 11 (1)

  Next, the positive electrode body 4 is positioned at the center of the two metal rods 11 and 11 and the side facing the negative electrode is on the upper side, so that the positive electrode body 4 is placed on the two metal rods 11 and 11. Leave on top. Further, as the pressurizing jig 13, the two metal bodies (made of stainless steel) having a radius of curvature of 0.5 mm at the tip portion (tip portion on the side in contact with the positive electrode body 4) having the shape shown in FIG. As shown in FIG. 2B, the center of the positive electrode body 4 is pushed down at a speed of 0.5 mm / min in the vertical direction. At this time, the load (N) by which the pressing jig 13 pushes down the positive electrode body 4 is measured, and the maximum value of the load measured until the pushing amount reaches Lv / 4 (mm): P (N) is obtained. The bending strength: T (N / cm) of the positive electrode body is calculated by the following formula (2).

    T = P × 10 / W (2)

  As standard conditions, the diameter of the positive electrode body: W may be about 11 mm.

  In order to adjust the bending strength of the positive electrode body to the above-mentioned value, the material used for the positive electrode body and the composition thereof may be adjusted. For example, when the positive electrode body is configured using a catalyst layer and a current collector. May adjust the intensity of the current collector to an appropriate range. Specifically, it is preferable to use a current collector having a bending strength of 0.3 N / cm or more and 3.2 N / cm or less. As the current collector satisfying the above-mentioned value for the bending strength, a metal or carbon net such as titanium, nickel, stainless steel, foil, expanded metal, punching metal, foamed base material, or the like can be used. When using a net, expanded metal, or foamed base material, the bending strength can be adjusted by adjusting the wire diameter, opening diameter, tensile strength of the wire, etc.When using foil or punching metal, The bending strength can be obtained by adjusting the thickness, the aperture ratio, or the like, or by calendering or heat treatment. In particular, when a metal net is used for the current collector of the positive electrode body, it is preferable because the bending strength of the positive electrode body can be easily adjusted to the above range.

  In addition, the bending strength of the current collector referred to in this specification can also be obtained for the circular current collector by the same method as the measurement of the bending strength of the positive electrode body described above.

  For the above reason, in the air battery of the present invention, the maximum height from the bottom inner surface of the positive electrode case to the surface on the negative electrode case side of the positive electrode body is a (mm), and from the bottom inner surface of the positive electrode case to the negative electrode case When the height to the inner surface of the bottom part is b (mm), the ratio a / b is preferably 0.25 or more.

  The height a and the height b mean the lengths a and b shown in FIG. 1. Both the height a and the height b have the positive electrode case on the lower side and the battery is placed. It is the maximum value of the distances in the direction perpendicular to the bottom surface of the positive electrode case. For example, as shown in FIG. 1, when a step is provided at the bottom of the positive electrode case, the distance is from the lower part of the bottom step.

  By setting the ratio a / b to be 0.25 or more, preferably 0.3 or more, an area between the positive electrode body and the inner surface of the positive electrode case, that is, an area capable of holding air (empty space) is increased. Thus, the reactivity of the positive electrode (positive electrode body) can be increased.

  In general, in an air battery, metal particles such as zinc-based particles used for the negative electrode expand with the progress of the battery reaction. Therefore, as described above, a relatively large empty space is provided in the negative electrode case to perform electrolysis accompanying discharge. Liquid leakage (leakage) is suppressed. However, this reduces the contact area between the inner surface of the negative electrode case that also serves as the negative electrode current collector and the negative electrode, so that electric conduction is impaired and sufficient load characteristics tend not to be obtained.

  On the other hand, in the air battery of the present invention, by using a positive electrode body with low bending strength, the value of ratio a / b can be easily adjusted to the above preferred range during battery assembly, and excellent load characteristics can be easily secured. .

  Further, when the value of the ratio a / b increases, the volume of the space in which the negative electrode can be accommodated, that is, the space formed between the separator and the negative electrode case decreases, and the ratio of the negative electrode volume to the volume, That is, since the filling rate of the negative electrode is increased, the contact area between the inner surface of the negative electrode case and the negative electrode is increased, and the reactivity of the negative electrode is easily improved.

  On the other hand, the volume decrease of the space on the negative electrode side leads to an increase in the space on the positive electrode side, that is, the empty space between the positive electrode body and the inner surface of the positive electrode case, and absorbs the expansion of the negative electrode as the battery reaction proceeds. Since the volume of the space that can be produced does not substantially change, the leakage resistance of the battery is maintained.

  In addition, from the viewpoint of further enhancing the effect of improving the reactivity of the negative electrode by improving the electric conduction between the inner surface of the negative electrode case and the negative electrode, the filling factor of the negative electrode is preferably 60% or more, and 65% or more. More preferably, it is 70% or more, and most preferably 80% or more. The filling rate of the negative electrode may be 100%.

  The filling rate of the negative electrode as used herein is calculated based on the volume of the composition constituting the negative electrode and the volume of the space formed between the separator and the negative electrode case. Specifically, the volume of the composition can be calculated from the volume of the entire composition constituting the negative electrode, such as an electrolytic solution, in addition to the metal particles serving as the active material. The volume of the space formed between the separator and the negative electrode case is a volume of a space that is formed after the battery is assembled and can contain the composition constituting the negative electrode. This corresponds to the sum of the volume of the entire composition to be formed and the volume of the empty space (space in which the negative electrode is not filled) formed between the separator and the negative electrode case.

The volume of the space formed between the separator and the negative electrode case is determined by, for example, cutting the battery in the thickness direction at the center, and using a dynascope to coordinate the cross section, and then using 3D CAD or the like as the center line The volume can be estimated by rotating the cross-section once from (the filling rate of the negative electrode shown in the examples described later is determined based on the volume of the space estimated using 3D CAD by this method and the composition of the composition constituting the negative electrode. It is a value obtained from the volume). Alternatively, it is possible to estimate the volume of the space on the negative electrode side nondestructively from the X-ray CT image.

  If the ratio a / b is too large, for example, the area for accommodating the negative electrode becomes too small and the capacity of the battery may be impaired. Therefore, the ratio a / b is preferably 0.5 or less. More preferably, it is 0.45 or less.

  The height a and the height b referred to in the present specification are, for example, obtained by cutting the battery in the thickness direction at the center, and using a dynascope to coordinate the cross section, and then estimating the height using CAD or the like. (The height a and the height b shown in the examples described later are values estimated using CAD in this method). Alternatively, it is possible to estimate the value from an X-ray CT image.

  As described above, for example, a positive electrode body of an air battery having a structure in which a catalyst layer and a current collector are laminated can be used.

  In addition to the catalyst, the catalyst layer may contain a binder, for example.

The catalyst according to the catalyst layer, for example, silver, platinum group metals or alloys thereof, transition metals, platinum / metal oxide, such as Pt / IrO _2, perovskite oxides such as _{La 1-x Ca x CoO 3} , phthalocyanine iron Complex catalysts such as WC, carbides such as WC, nitrides such as Mn ₄ N, manganese oxides such as manganese dioxide, and the like are used. Among these, manganese oxides such as manganese dioxide are more preferable. Various carbons described later (carbons that can be used in the catalyst layer) can also be used as a catalyst. The catalyst content in the catalyst layer is preferably 0.5 to 70% by mass.

  By using carbon as a material for forming the catalyst layer together with a catalyst other than carbon, the carbon functions as a carrier for the catalyst when the catalyst layer is formed. Further, in forming the catalyst layer, a catalyst other than carbon and carbon may not be used individually, but may be used for forming the catalyst layer in a state where a catalyst other than carbon is supported on carbon in advance.

  Carbon used in the catalyst layer includes graphite, graphene, carbon black (acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, etc.), VGCF (vapor phase carbon fiber), carbon nanotube, charcoal And activated carbon. When a catalyst other than carbon and carbon are used together, the carbon content in the catalyst layer is preferably 20 to 90% by mass.

  Examples of the binder for the catalyst layer include a vinylidene fluoride polymer [polyvinylidene fluoride (PVDF)], a tetrafluoroethylene polymer [polytetrafluoroethylene (PTFE)], a vinylidene fluoride copolymer, and tetrafluoroethylene. Copolymers [vinylidene fluoride-hexafluoropropylene copolymer (PVDF-HFP), vinylidene fluoride-chlorotrifluoroethylene copolymer (PVDF-CTFE), vinylidene fluoride-tetrafluoroethylene copolymer (PVDF -TFE), vinylidene fluoride-hexafluoropropylene-tetrafluoroethylene copolymer (PVDF-HFP-TFE), etc.]. Among these, a tetrafluoroethylene polymer or copolymer is preferable, and PTFE is more preferable. The binder content in the catalyst layer is preferably 3 to 50% by mass.

  The thickness of the catalyst layer in the positive electrode body is preferably 100 to 500 μm. Moreover, it is preferable that the thickness of the collector which concerns on a positive electrode body is 50-300 micrometers.

  Therefore, the thickness of the positive electrode body can be, for example, the total value of the preferable thickness of the catalyst layer and the preferable thickness of the current collector, but is more preferably 300 μm or less.

  The catalyst layer can be produced, for example, by mixing the catalyst, carbon used as necessary, binder, etc. with water, rolling with a roll, and closely adhering to the current collector. In addition, after the catalyst layer forming composition (slurry, paste, etc.) prepared by dispersing the above-mentioned catalyst or a binder used as necessary in water or an organic solvent is applied to the surface of the current collector and dried. If necessary, it can also be manufactured through a step of performing a pressing process such as a calendar process.

  As the negative electrode of the air battery, one containing zinc-based particles or magnesium-based particles is used. In such a negative electrode, zinc and magnesium in the particles act as an active material. Examples of the alloy component of the zinc alloy particles include indium (for example, the content is 50 to 500 ppm on a mass basis), bismuth (for example, the content is 50 to 500 ppm on a mass basis), and aluminum (for example, the content is 10 to 10 on a mass basis). 1500 ppm) (the balance is zinc and inevitable impurities).

  Moreover, as an alloy component of magnesium alloy particles, for example, calcium (for example, the content is 1 to 3% on a mass basis), manganese (for example, the content is 0.1 to 0.5% on a mass basis), zinc (for example, The content is 0.4 to 1% on the basis of mass), aluminum (for example, the content is 8 to 10% on the basis of mass), etc. (the balance is magnesium and inevitable impurities).

  The metal particles possessed by the negative electrode may be one type alone or two or more types.

  However, it is preferable to use metal particles that do not contain mercury as an alloy component from the viewpoint of reducing environmental burden. For the same reason as in the case of mercury, it is preferable to use metal particles that do not contain lead as an alloy component.

  The particle size of the zinc-based particles is, for example, preferably 50% by mass or less, more preferably 30% by mass or less of all particles having a particle size of 75 μm or less, and a particle size of 100 to 100%. The thing whose ratio of the particle | grains of 200 micrometers is 50 mass% or more, More preferably, it is 90 mass% or more is mentioned.

  As the particle size of the magnesium-based particles, for example, the proportion of particles having a particle size of 30 μm or less in all particles is preferably 50% by mass or less, more preferably 30% by mass or less, and the particle size is The thing whose ratio of the particle | grains of 50-200 micrometers is 50 mass% or more, More preferably is 90 mass% or more.

The particle size in the metal particles referred to in the present specification was measured by using a laser scattering particle size distribution meter (for example, “LA-920” manufactured by HORIBA, Ltd.) and measuring these particles by dispersing them in a medium that does not dissolve the particles. The particle size (D ₅₀ ) at a cumulative frequency of 50%.

  The negative electrode may contain, for example, a gelling agent (polyacrylic acid soda, carboxymethyl cellulose, etc.) added as necessary in addition to the metal particles, and is configured by adding an electrolyte to this. A negative electrode agent (gelled negative electrode) may be used. The amount of the gelling agent in the negative electrode is preferably 0.5 to 1.5% by mass, for example.

  The negative electrode can also be a non-gelled negative electrode that does not substantially contain the gelling agent as described above (in the case of a non-gelled negative electrode, the electrolyte present in the vicinity of the metal particles is thickened). Otherwise, it may contain a gelling agent, so “substantially does not contain a gelling agent” means that it may be contained to the extent that it does not affect the viscosity of the electrolyte. ). In the case of a gelled negative electrode, an electrolytic solution is present together with a gelling agent in the vicinity of the metal particles, but this electrolytic solution is thickened by the action of the gelling agent. The movement of ions in the liquid is suppressed. For this reason, the reaction rate at the negative electrode is suppressed, which is considered to hinder the improvement of the load characteristics (particularly heavy load characteristics) of the battery. On the other hand, the negative electrode is made non-gelled, and the reaction rate at the negative electrode is increased by keeping the ion moving speed in the electrolytic solution high without increasing the viscosity of the electrolytic solution existing in the vicinity of the metal particles. Characteristics (particularly heavy load characteristics) can be further enhanced.

  As the electrolytic solution to be contained in the negative electrode, the same electrolyte as that injected into the battery can be used.

  The metal particle content in the negative electrode is, for example, preferably 60% by mass or more, more preferably 65% by mass or more, and preferably 75% by mass or less, and 70% by mass or less. It is more preferable.

  The negative electrode preferably contains an indium compound. When the negative electrode contains an indium compound, generation of hydrogen gas due to a corrosion reaction between the metal particles and the electrolytic solution can be more effectively prevented.

  Examples of the indium compound include indium oxide and indium hydroxide.

  The amount of the indium compound used for the negative electrode is preferably 0.003 to 1 with respect to 100 metal particles in terms of mass ratio.

  Examples of the electrolyte solution for an air battery (including an electrolyte solution injected into the battery and an electrolyte solution contained in the negative electrode) include alkali metal hydroxides (if the metal particles of the negative electrode are zinc-based particles) An alkaline electrolyte such as one or more aqueous solutions of sodium hydroxide, potassium hydroxide, lithium hydroxide and the like is preferably used, and an aqueous solution of potassium hydroxide is particularly preferred. The concentration of the electrolytic solution is, for example, in the case of an aqueous solution of potassium hydroxide, potassium hydroxide is preferably 20% by mass or more, more preferably 30% by mass or more, and preferably 40% by mass or less, more preferably 38%. It is below mass%. By adjusting the concentration of the aqueous solution of potassium hydroxide to such a value, an electrolytic solution having excellent conductivity can be obtained.

  In addition, when the metal particles of the negative electrode are magnesium-based particles, aqueous solutions having a pH of 10 or less, such as acidic aqueous solutions, neutral aqueous solutions, and weak alkaline aqueous solutions, are preferably used. Examples of electrolytes such as salts dissolved in an aqueous solution used as an electrolyte include chlorides such as sodium chloride, hydroxides such as sodium hydroxide, bicarbonates such as sodium bicarbonate, percarbonates such as sodium percarbonate, Examples include compounds containing halogen such as fluoride, polyvalent carboxylic acids, and the like, and the electrolytic solution only needs to contain one or more of these electrolytes. Among such electrolytic solutions, a chloride aqueous solution such as a sodium chloride aqueous solution is more preferable.

  For example, in the case of a sodium chloride aqueous solution, the concentration of the sodium chloride is preferably 1 to 20% by mass.

  In any case, it is preferable that an indium compound is dissolved in the electrolytic solution. When the indium compound is dissolved in the electrolytic solution, generation of hydrogen gas in the battery can be suppressed more favorably.

  Examples of the indium compound dissolved in the electrolyte include indium hydroxide, indium oxide, indium sulfate, indium sulfide, indium nitrate, indium bromide, and indium chloride.

  The concentration of the indium compound in the electrolyte solution is preferably 50 ppm or more, more preferably 100 ppm or more, particularly preferably 500 ppm or more, and preferably 10,000 ppm or less, based on mass. It is more preferably 5000 ppm or less, and particularly preferably 1000 ppm or less.

  In addition to the above-described components, various known additives may be added to the electrolytic solution as necessary within a range not impairing the effects of the present invention. For example, zinc oxide may be added in order to prevent corrosion (oxidation) of metal particles used for the negative electrode. Zinc oxide can also be added to the negative electrode.

  In the air battery, the separator interposed between the positive electrode and the negative electrode is a nonwoven fabric mainly composed of vinylon and rayon, a vinylon / rayon nonwoven fabric (vinylon / rayon mixed paper), a polyamide nonwoven fabric, a polyolefin / rayon nonwoven fabric, a vinylon paper, a vinylon. -Linter pulp paper, vinylon mercerized pulp paper, etc. can be used. A hydrophilic microporous polyolefin film (microporous polyethylene film, microporous polypropylene film, etc.), cellophane film, and liquid absorbing layer (electrolyte holding layer) such as vinylon / rayon mixed paper were stacked. It is good also as a separator. The thickness of the separator is preferably 20 to 500 μm.

  For the air diffusion film according to the air battery, a non-woven fabric made of a resin such as cellulose, polyvinyl alcohol, polypropylene, or nylon can be used. The thickness of the air diffusion film is preferably 100 to 250 μm.

  As the water-repellent film for the air battery, a film that has water repellency while allowing air to permeate is used. Specifically, for example, a fluorine resin such as PTFE; a polyolefin such as polypropylene or polyethylene; Film can be used. The thickness of the water repellent film is preferably 50 μm or more, preferably 250 μm or less, and more preferably 150 μm or less.

  The air battery according to the present invention has, for example, a battery case in which a positive electrode case and a negative electrode case are caulked and sealed via a gasket as shown in FIG. It has a flat shape (including coin shape and button shape).

  In addition, when caulking the battery case, polypropylene, nylon, etc. can be used as the gasket material interposed between the positive electrode case and the negative electrode case, and heat resistance is required in relation to the use of the battery. In some cases, fluororesin such as tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA), polyphenylene ether (PEE), polysulfone (PSF), polyarylate (PAR), polyethersulfone (PES), polyphenylene sulfide It is also possible to use a heat-resistant resin having a melting point exceeding 240 ° C. such as (PPS) or polyether ether ketone (PEEK). Further, when the battery is applied to an application requiring heat resistance, a glass hermetic seal can be used for the sealing.

  In order to prevent elements such as iron constituting the positive electrode case from eluting at the time of charging, it is desirable to plate the inner surface of the positive electrode case with a corrosion-resistant metal such as tin, zinc, or indium.

  The air battery of the present invention can be applied to, for example, the same use as a use of a conventionally known air battery.

  Hereinafter, the present invention will be described in detail based on examples. However, the following examples do not limit the present invention.

Example 1
<Positive electrode body>
Manganese (III) oxide (Mn ₂ O ₃ ) (catalyst): 40 parts by mass, ketjen black (carbon): 50 parts by mass, PTFE: 10 parts by mass, water, and roll-rolled to obtain a thickness A positive electrode sheet (air electrode) was prepared by forming a positive electrode sheet for a catalyst layer having a thickness of 350 μm and punching it into a circle having a diameter of 11 mm. In addition, the weight of the catalyst layer of this positive electrode body was 35 mg.

  Next, according to the procedure described above, the bending strength of the positive electrode body was measured by setting the distance Lv between the metal rods 11 and 11 to 8 mm. When the load (N) was measured while pressing the center of the positive electrode body in the vertical direction at a speed of 0.5 mm / min with a pressurizing jig having the tip shape shown in FIG. 2 (c), the indentation amount was 2 mm. The maximum value of the load measured until it reached was found to be 0.7 (N), and the bending strength of the positive electrode body was calculated to be 0.64 (N / cm) from Equation (2).

<Negative electrode>
As the negative electrode active material, zinc alloy particles: 850 mg containing In: 500 ppm, Bi: 400 ppm and Al: 10 ppm as additive elements were used. The zinc alloy particles had an average particle size (D ₅₀ ) of 120 μm and a proportion of particles having a particle size of 75 μm or less was 25% by mass or less. For the negative electrode, a composition in which an amount of indium hydroxide in an amount of 0.3 with respect to the zinc alloy particles: 100 was mixed was used.

<Electrolyte>
As the electrolytic solution, a 35% by mass potassium hydroxide aqueous solution in which 200 ppm of indium hydroxide was dissolved on a mass basis was used.

<Separator>
In the separator, two graft films (thickness: 30 μm) composed of a graft copolymer having a structure in which acrylic acid is graft-copolymerized to a polyethylene main chain are arranged on both sides of a cellophane film (thickness: 20 μm). Further, a laminate of vinylon-rayon mixed paper (thickness: 100 μm) was punched and used.

<Air diffusion film and water repellent film>
For the air diffusion membrane, a cellulose nonwoven fabric (paper) having a thickness of 100 μm was used by punching to a diameter of 7 mm. As the water repellent film, a PTFE sheet having a thickness of 100 μm was used by punching to a diameter of 11 mm.

<Battery assembly>
An outer can having the above-mentioned air diffusion film, water-repellent film, air electrode, separator, negative electrode composition, and electrolyte solution, made of a steel plate tin-plated on its inner surface and having five air holes on the bottom surface with a diameter of 11 mm; -Stainless steel (SUS304)-Housed in a battery case composed of a sealing plate made of nickel clad plate and an annular gasket made of nylon 66, having the structure shown in Fig. 1, having a diameter of 11 mm and a thickness of 5. A 4 mm air battery was produced. In the obtained battery, the maximum height from the bottom inner surface of the positive electrode case to the surface on the negative electrode case side of the positive electrode body: a is 1.7 mm, and the height from the bottom inner surface of the positive electrode case to the bottom inner surface of the negative electrode case : B was 5.2 mm, and the ratio a / b was 0.33. In addition, the filling factor of the negative electrode was 73.1%, and the theoretical electric quantity of the negative electrode was 692 mAh.

(Example 2)
As the positive electrode current collector, a stainless steel mesh having a wire diameter of 100 μm and a length of 1.0 mm × width of 1.0 mm was used, and the positive electrode sheet produced in Example 1 was pressure-bonded to the stainless steel mesh and dried. Thereafter, a positive electrode body having a bending strength of 2.04 (N / cm) was produced by punching into a circle having a diameter of 11 mm.

  An air battery having a ratio a / b of 0.33 was produced in the same manner as in Example 1 except that this positive electrode body was used. When the bending strength of the current collector punched into a circle having a diameter of 11 mm was determined, it was calculated to be 1.3 (N / cm).

(Example 3)
As the positive electrode current collector, Example 2 was used except that a stainless steel mesh (bending strength: 1.9 (N / cm)) having a wire diameter of 120 μm and a length of 1.0 mm × width of 1.0 mm was used. Similarly, an air battery having a ratio a / b of 0.33 was produced. The bending strength of the positive electrode body was 2.75 (N / cm).

(Comparative Example 1)
Example 2 except that a stainless steel mesh (bending strength: 2.7 (N / cm)) having a wire diameter of 120 μm and a mesh length of 0.7 mm × width of 0.7 mm was used as the positive electrode current collector. In the same manner as above, a positive electrode body having a bending strength of 3.44 (N / cm) was produced.

  An air battery having a ratio a / b of 0.25 was produced in the same manner as in Example 1 except that the battery was assembled using this positive electrode body.

(Comparative Example 2)
Example 2 except that a stainless steel net [bending strength: 7.0 (N / cm)] having a wire diameter of 150 μm and a mesh length of 0.55 mm × width of 0.55 mm was used as the current collector of the positive electrode body. In the same manner as above, a positive electrode body having a bending strength of 7.87 (N / cm) was produced.

  An air battery having a ratio a / b of 0.21 was produced in the same manner as in Example 1 except that the battery was assembled using this positive electrode body.

  About the air battery of an Example and a comparative example, the load characteristic and the leak-proof property were evaluated by the following method.

<Load characteristics>
For each air battery of the example and the comparative example, when a load resistance of 60Ω is connected and discharged at room temperature, the discharge capacity until the battery voltage decreases to 0.9V and the depth of discharge reaches 50%. The discharge voltage (closed circuit voltage) was measured and the load characteristics were evaluated.

<Leakage resistance>
The batteries that were discharged during the evaluation of the load characteristics were examined for leakage from the air holes and evaluated for leakage resistance.

  Table 1 shows the configuration and ratio a / b of the positive electrode according to each air battery of Examples and Comparative Examples, Table 2 shows the configuration of the negative electrode, and Table 3 shows the evaluation results.

  As shown in Tables 1 to 3, the air batteries of Examples 1 to 4 provided with a positive electrode body having an appropriate bending strength have a large discharge capacity at the time of load characteristic evaluation, a high discharge voltage, and excellent load characteristics. In addition, no liquid leakage was observed, and the liquid leakage resistance was good. Moreover, when the batteries of Examples 1 to 4 were compared, a tendency was found that the load characteristics improved as the bending strength of the positive electrode body decreased.

  In contrast, the batteries of Comparative Examples 1 and 2 having a positive electrode body with too high bending strength had a low discharge capacity and a low discharge voltage when evaluating the load characteristics, and the load characteristics were inferior to the batteries of the examples. . Further, the battery of Comparative Example 2 was leaked during the load characteristic evaluation.

DESCRIPTION OF SYMBOLS 1 Air battery 2 Exterior can 3 Sealing plate 4 Positive electrode body (air electrode)
5 Negative electrode 6 Separator 7 Air diffusion film 8 Water repellent film 9 Air hole 10 Resin gasket

Claims (8)

In a battery case composed of a positive electrode case having air holes, a negative electrode case, and a resin gasket, an air diffusion film, a water repellent film, a positive electrode body and a separator are accommodated in order from the bottom side of the positive electrode case, An air battery in which a negative electrode is accommodated between a separator and the negative electrode case,
The air battery according to claim 1, wherein the positive electrode body has a bending strength of 3.15 N / cm or less.   The maximum height from the bottom inner surface of the positive electrode case to the surface on the negative electrode case side of the positive electrode body is a (mm), and the height from the bottom inner surface of the positive electrode case to the bottom inner surface of the negative electrode case is b ( The air battery according to claim 1, wherein the ratio: a / b is 0.25 or more.   The air battery according to claim 1, wherein the positive electrode body has a catalyst layer containing a catalyst and a fluororesin binder, and a current collector made of a metal net.   The air battery according to claim 1, wherein the positive electrode body has a thickness of 300 μm or more.   The air battery according to claim 1, wherein the water repellent film has a thickness of 150 μm or less.   The air battery according to any one of claims 1 to 4, wherein a filling rate of the negative electrode with respect to a volume of a space formed between the separator and the negative electrode case is 60% or more. A method for producing the air battery according to claim 1,
A method for producing an air battery, wherein the positive electrode body is configured using a catalyst layer and a current collector having a bending strength of 3.2 N / cm or less.   The method for producing an air battery according to claim 7, wherein the positive electrode body having a catalyst layer containing a catalyst and a fluororesin binder and a current collector made of a metal net is used.

Images