JP2017228366A - Method for producing catalyst sheet and method of producing air electrode - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce and provide inexpensive catalyst sheets and air electrodes while achieving the smooth movement of electrons in a constitution using a manganese catalyst to improve polarization characteristics.SOLUTION: A catalyst sheet used for an air electrode 13 is obtained by: kneading carbon powder of a conductive material, an organic matter binder, and water; then molding and drying the kneaded product to prepare a sheet member; and performing a series of steps one or more times, each of the steps including impregnating a solution of a manganese catalyst precursor into the sheet member, drying the sheet member, and subjecting the sheet member to heat treatment.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a method for producing a catalyst sheet used for a battery electrode and a method for producing an air electrode.

  Conventionally, various oxygen reduction catalysts for the air electrode have been studied. For example, precious metals such as platinum group elements and silver deposited on activated carbon or carbon powder, mixed activated carbon and metal conversion products, and a mixture of an organometallic complex such as metal porphyrin and carbon powder, Alternatively, those heat-treated products are being studied. In general, noble metals such as platinum group elements and silver have a large catalytic effect. However, in primary batteries, it is difficult to regenerate and use the air electrode. Therefore, it is not practical to use an expensive material in view of cost. Therefore, manganese oxide has been tried as one of inexpensive catalysts (for example, see Patent Document 1).

Japanese Patent No. 5373966

However, as a method for applying a catalyst to an electrode, in the case of a method in which an electrode is manufactured by mixing a mixed powder obtained by adding catalyst powder to carbon powder or a powder supported on carbon powder together with a binder, There is a drawback in that the electrical connection is broken and the important electrical connection in the electrode becomes poor. For this reason, in the electrode, the electron transfer from the reaction field on the catalyst surface is not smooth, and the charge transfer resistance increases, so that it is difficult to obtain sufficient performance of the air electrode.
Accordingly, an object of the present invention is to produce and provide a catalyst sheet and an air electrode that can facilitate electron transfer with a configuration using a manganese catalyst, improve polarization characteristics, and are inexpensive.

  In order to achieve the above object, the present invention provides a method for producing a catalyst sheet used in a battery electrode, wherein a conductive material, an organic binder, and water are kneaded, and then molded and dried to produce a sheet member. In addition, a series of steps of impregnating, drying, and heat-treating the manganese catalyst precursor solution is performed once or a plurality of times to obtain a catalyst sheet carrying a target amount of catalyst.

  The said structure WHEREIN: The said sheet | seat member is knead | mixed with water after the said electrically conductive material, manganese dioxide powder, and the said organic substance binder, It shape | molds and dries, It is characterized by the above-mentioned. In the above configuration, a manganese nitrate aqueous solution may be used as the solution of the manganese catalyst precursor.

  In the above structure, electrolytic manganese dioxide may be used as the manganese dioxide powder. In the above structure, a polymer dispersion having a higher melting point than the temperature at which the heat treatment is performed may be used as the organic binder.

  Further, the present invention provides a method for producing an air electrode used in an air battery, wherein a conductive member, an organic binder, and water are kneaded and then molded and dried to produce a sheet member. A series of steps of impregnating, drying, and heat-treating the solution of the catalyst is performed once or a plurality of times to obtain a catalyst sheet carrying the target amount of catalyst, and obtained by pressure-bonding the catalyst sheet to a current collector Features.

  In the above structure, the sheet member is produced by kneading the conductive material, manganese dioxide powder, and the organic binder with water, and then molding and drying.

  In the present invention, after kneading a conductive material, an organic binder, and water, forming and drying to produce a sheet member, the sheet member is impregnated with a solution of a manganese catalyst precursor, dried, and heat-treated, Since the catalyst sheet carrying the target amount of catalyst is obtained once or multiple times, the structure using the manganese catalyst enables smooth electron transfer, improves polarization characteristics, and provides an inexpensive catalyst sheet and air electrode. It can be made easier to manufacture.

It is the figure which showed typically the cross-sectional structure of the air battery. It is the figure which showed the test result. It is the figure which showed the test result.

Hereinafter, an embodiment of the present invention will be described.
The catalyst sheet which concerns on embodiment of this invention is used for the air electrode of an air battery.
FIG. 1 is a diagram schematically showing a cross-sectional structure of an air battery.
The air battery 10 includes an exterior body 11 formed of a plastic case made of resin, and an air electrode 13 and a metal electrode 15 that constitute a pair of electrodes are disposed opposite to the exterior body 11 with a space therebetween. The air battery 10 is a primary battery in which the air electrode 13 acts as a positive electrode and the metal electrode 15 acts as a negative electrode when an electrolyte is injected into the outer package 11. In FIG. 1, the symbol UL indicates the liquid level of the electrolytic solution.

  The exterior body 11 is formed in a hollow box shape, and a rectangular opening 11K is provided on the front surface constituting the largest surface of the exterior body 11. The air electrode 13 is attached to the exterior body 11 so as to cover the opening 11K. Further, the metal electrode 15 is inserted from a metal electrode insertion opening formed on the upper surface of the exterior body 11, and is fixed by a holding member 11 </ b> A and a support member 11 </ b> B formed inside the exterior body 11.

  The exterior body 11 may be a sheet material containing paper, and the sheet material may be a sheet material provided with a film on the surface of the paper constituting the base material. As the sheet material, paper having at least an inner surface laminated with a heat-fusible resin (for example, polyethylene (PE)), that is, laminated paper can be used.

The air electrode 13 includes a current collector and a catalyst sheet that forms a catalyst layer for oxygen reduction, and is fixed to the exterior body 11 by adhesion or the like. The air electrode 13 has air permeability that allows external air to pass through the exterior body 11 and non-liquid permeability that does not leak electrolyte.
The metal electrode 15 is supported in the exterior body 11 so as to face the air electrode 13. The structure for supporting the metal electrode 15 may be fixed by the sandwiching member 11A and the support member 11B arranged in the exterior body 11 as described above, or by a lid portion of the exterior body 11 that is separately formed. Various support structures such as supporting the metal electrode 15 can be applied.

The metal electrode 15 is formed of a magnesium alloy plate and is disposed in parallel with the air electrode 13. A sodium chloride aqueous solution is used as the electrolytic solution. That is, the air battery 10 of the present embodiment is a magnesium air battery (metal air battery).
Since the magnesium air battery can use seawater as an electrolytic solution or a liquid obtained by mixing a salt with tap water, it is easy to procure the electrolytic solution. In addition, a bag body containing sodium chloride as an electrolyte may be arranged in advance in the exterior body 11, and power may be generated simply by injecting water such as tap water.

  The metal electrode 15 is not limited to a magnesium alloy, and a metal such as zinc, iron, aluminum, or an alloy thereof may be used. When zinc is used for the metal electrode 15, a potassium hydroxide aqueous solution may be used as the electrolytic solution, and when iron is used for the metal electrode 15, an alkaline aqueous solution may be used as the electrolytic solution. In addition, when aluminum is used for the metal electrode 15, an electrolytic solution containing sodium hydroxide or potassium hydroxide may be used.

The air electrode 13 will be described.
The current collector of the air electrode 13 is a rectangular copper mesh (copper network). In addition, it is not limited to a copper mesh, The porous electrical power collector which has porous structures other than copper mesh, such as a metal mesh using metals other than copper, is widely applicable.
The catalyst sheet is a sheet containing at least a conductive material (conductive material) and a manganese catalyst. In this catalyst sheet, a conductive material and an organic binder are kneaded in a dispersion medium in which a manganese catalyst precursor is dispersed, and then molded and dried to produce a sheet member. The sheet member is impregnated with a solution of the manganese catalyst precursor. A series of steps of drying, heat treatment is performed once or a plurality of times to produce a sheet carrying the target amount of catalyst. The catalyst sheet is cut into a sheet having a predetermined size, and is then pressed onto both sides of the copper mesh to be integrated with the copper mesh.

The step of forming the catalyst sheet into a sheet is performed, for example, by pressing the paste between PET films and using a roller press. Moreover, the process of pressure-bonding the catalyst sheet to the copper mesh (current collector) is performed by pressing with a press. Various known devices may be applied to these processes. For example, the crimping may be performed using a dedicated crimping device (including jigs) suitable for crimping the catalyst sheet and the copper mesh. good.
As will be described later, since the catalyst sheet is prepared by kneading and firing a granular redox catalyst, a binder, etc., it has irregularities on the surface, and even after pressing with a roller press machine, it has some irregularities. It will have a state.

The conductive material is carbon powder. More specifically, it is a powder of carbon black such as ketjen black (KB), carbon whisker, graphite, graphite whisker, activated carbon, carbon nanotube, carbon nanowire, or carbon nanohorn. In addition, you may use electrically conductive materials other than carbon, such as metal materials, such as copper and aluminum, or organic electroconductive materials, such as a polyphenylene derivative, for this electrically conductive material.
The organic binder is a polymer dispersion, specifically, a fluorine-based resin such as polytetrafluoroethylene (also referred to as PTFE or Teflon (registered trademark)), or a polyolefin-based resin such as polypropylene (PP). It is a thermoplastic resin.

  The dispersion medium includes a solution of a manganese catalyst precursor. This solution is not particularly limited as long as the desired manganese catalyst (manganese oxide) can be obtained. In this embodiment, the target manganese catalyst is manganese dioxide, and the manganese catalyst precursor is manganese (II) nitrate hexahydrate or manganese acetate (II) tetrahydrate. Instead of manganese nitrate (II) hexahydrate or manganese acetate (II) tetrahydrate, other divalent manganese salt aqueous solutions may be used.

1. (Example)
Next, examples and comparative examples will be described. Each Example and Comparative Example have the same configuration except that the catalyst sheet is different. Hereinafter, the catalyst sheet will be described. Information on each catalyst sheet is shown in Table 1.

KB as an electrically conductive material and PTFE as an organic binder and water were kneaded, and the kneading was continued until fibrillation of PTFE occurred and the viscosity change was stabilized, thereby preparing a paste having a predetermined viscosity. This paste was sandwiched between PET films, and a sheet member having a predetermined thickness was produced by a roller press set to a roll gap of 1 mm. This sheet member was dried at 80 ° C. for 2 hours to prepare a catalyst sheet containing no manganese catalyst. Hereinafter, for the convenience of explanation, this catalyst sheet is referred to as a first catalyst sheet.
1.1 (Example 1)
After an appropriate amount of ethanol was sprayed on the first catalyst sheet, the first catalyst sheet was placed in a 2M aqueous manganese nitrate solution in which manganese (II) nitrate hexahydrate was dissolved, and the aqueous manganese nitrate solution was vacuum impregnated in the sheet. After removing the excess liquid, drying was performed at 80 ° C. for 2 hours with a dryer, and then heat treatment was performed at 120 ° C. for 2 hours as a baking treatment. Thereafter, a heat treatment was performed at 200 ° C. for 30 minutes as a PTFE sintering treatment.
This heat treatment was carried out in the presence of air and in an atmospheric pressure environment. By this heat treatment, manganese dioxide is precipitated by thermal decomposition of manganese (II) nitrate, and fixation and loading of manganese dioxide are completed. In addition, when using manganese nitrate, it has confirmed that manganese dioxide can be obtained if it is about 120 degreeC or more as a baking process.

1.2 (Example 2)
After an appropriate amount of ethanol was sprayed on the first catalyst sheet, the first catalyst sheet was placed in a 2M aqueous manganese nitrate solution in which manganese (II) nitrate hexahydrate was dissolved, and the aqueous manganese nitrate solution was vacuum impregnated in the sheet. After removing the excess liquid, drying was performed at 80 ° C. for 2 hours with a dryer, and then heat treatment was performed at 120 ° C. for 2 hours as a baking treatment. Furthermore, a series of treatments including the above impregnation, drying and heat treatment was performed on the catalyst sheet after firing three times in total. Thereafter, a heat treatment was performed at 200 ° C. for 30 minutes as a PTFE sintering treatment.
In addition, the heat processing of Example 2 and Examples 3 to 6 and Comparative Example described below are performed in the presence of the atmosphere and in an atmosphere of atmospheric pressure as in Example 1.

1.3 (Example 3)
After an appropriate amount of ethanol was sprayed on the first catalyst sheet, the first catalyst sheet was placed in a 2M aqueous manganese nitrate solution in which manganese (II) nitrate hexahydrate was dissolved, and the aqueous manganese nitrate solution was vacuum impregnated in the sheet. After removing the excess liquid, drying was performed at 80 ° C. for 2 hours with a dryer, and then heat treatment was performed at 120 ° C. for 2 hours as a baking treatment. Furthermore, a series of treatments consisting of the above impregnation, drying and heat treatment was performed on the calcined catalyst sheet 5 times in total. Thereafter, a heat treatment was performed at 200 ° C. for 30 minutes as a PTFE sintering treatment.
That is, Example 3 is different from Example 2 in that a series of treatments including impregnation, drying, and heat treatment is performed a total of five times.

1.4 (Example 4)
After an appropriate amount of ethanol was sprayed on the first catalyst sheet, the first catalyst sheet was placed in a 2M aqueous manganese nitrate solution in which manganese (II) nitrate hexahydrate was dissolved, and the aqueous manganese nitrate solution was vacuum impregnated in the sheet. After removing the excess liquid, drying was performed at 80 ° C. for 2 hours with a dryer, and then heat treatment was performed at 120 ° C. for 2 hours as a baking treatment. Furthermore, a series of treatments consisting of the above impregnation, drying and heat treatment were performed on the catalyst sheet after calcination a total of 7 times. Thereafter, a heat treatment was performed at 200 ° C. for 30 minutes as a PTFE sintering treatment.
That is, Example 4 is different from Example 2 in that a series of treatments including impregnation, drying, and heat treatment is performed a total of seven times.

1.5 (Example 5)
A first catalyst sheet is prepared by replacing PTFE with PP as an organic binder, and the first catalyst sheet is placed in a 2M manganese nitrate aqueous solution in which manganese (II) nitrate hexahydrate is dissolved. Vacuum impregnation. After removing the excess liquid, drying was performed at 80 ° C. for 2 hours with a dryer, and then heat treatment was performed at 120 ° C. for 2 hours as a baking treatment. Furthermore, a series of treatments consisting of the above impregnation, drying and heat treatment was performed on the calcined catalyst sheet 5 times in total. Thereafter, as a PP sintering process, a heat treatment was performed at 140 ° C. for 30 minutes.
That is, Example 5 is different from Example 2 in that PP is used as the organic binder and a series of treatments including impregnation, drying, and heat treatment is performed five times in total.
Since the melting point of PP is about 165 ° C., the temperature of the sintering process was set to 140 ° C.

1.6 (Example 6)
After an appropriate amount of ethanol was sprayed onto the first catalyst sheet, the first catalyst sheet was placed in a 2M aqueous manganese acetate solution in which manganese (II) acetate tetrahydrate was dissolved, and the aqueous manganese acetate solution was vacuum impregnated into the sheet. After removing the excess liquid, drying was performed at 80 ° C. for 2 hours with a dryer, and then heat treatment was performed at 200 ° C. for 2 hours as a baking treatment. Furthermore, a series of treatments consisting of the above impregnation, drying and heat treatment was performed on the calcined catalyst sheet 5 times in total. Thereafter, a heat treatment was performed at 200 ° C. for 30 minutes as a PTFE sintering treatment.
That is, Example 6 differs from Example 3 in that manganese acetate is used.

2. (Comparative example)
2.1 (Comparative Example 1)
The first catalyst sheet was heat treated at 200 ° C. for 30 minutes. That is, the catalyst sheet of Comparative Example 1 does not contain a manganese catalyst.

2.2 (Comparative Example 2)
A catalyst sheet was prepared by mixing KB and manganese dioxide powder as a conductive material at a ratio of 9: 1, kneading PTFE and water as an organic binder, and drying the mixture.
That is, Comparative Example 2 was a catalyst sheet containing 10% manganese dioxide by a method of simply adding manganese dioxide powder. As the manganese dioxide powder, dry cell grade electrolytic manganese dioxide (EMD) powder was used. Finally, heat treatment (baking treatment) was performed at 200 ° C. for 30 minutes.

2.3 (Comparative Example 3)
As a conductive material, KB and 1M manganese nitrate aqueous solution in which manganese (II) nitrate hexahydrate is dissolved are kneaded so that KB and manganese dioxide powder have a ratio of 9: 1. Dried for 24 hours. Thereafter, heat treatment was performed at 120 ° C. for 24 hours to prepare catalyst powder having manganese dioxide supported on the surface. A catalyst sheet was prepared by kneading PTFE and water as the catalyst powder and an organic binder. Finally, heat treatment (baking treatment) was performed at 200 ° C. for 30 minutes.
That is, the comparative example 3 is different from the comparative example 2 in that a powder in which manganese dioxide is deposited and supported on the carbon surface is mixed to obtain a catalyst sheet containing 10% manganese dioxide.

2.4 (Comparative Example 4)
A catalyst sheet (a sheet corresponding to the first catalyst sheet) was prepared by changing PTFE as the organic binder and PE as the binder. This catalyst sheet was placed in a 2M aqueous manganese nitrate solution in which manganese (II) nitrate hexahydrate was dissolved, and the aqueous manganese nitrate solution was vacuum impregnated in the sheet. After removing the excess liquid, drying was performed at 80 ° C. for 2 hours with a dryer, and then heat treatment was performed at 120 ° C. for 2 hours as a baking treatment.
However, since polyethylene has a low melting point, the polyethylene melts and aggregates, and the strength cannot be obtained, making it impossible to produce a catalyst sheet. In addition, melting | fusing point of polyethylene is 95-130 degreeC with a low density polyethylene. On the other hand, the melting point of PTFE is 327 ° C., and the melting point of PP is about 165 ° C.

2.5 (Comparative Example 5)
A catalyst sheet (a sheet corresponding to the first catalyst sheet) was produced by changing PTFE as the organic binder and PP as the binder. The catalyst sheet was placed in a 2M aqueous manganese acetate solution in which manganese (II) acetate tetrahydrate was dissolved, and the aqueous manganese nitrate solution was vacuum impregnated in the sheet. After removing the excess liquid, drying was performed at 80 ° C. for 2 hours using a dryer, and then heat treatment was performed at 200 ° C. for 2 hours as a baking treatment.
However, since the polypropylene melted and aggregated, the strength was not obtained, and it was impossible to produce a catalyst sheet.

3. (Evaluation test)
Each catalyst sheet except Comparative Examples 4 and 5 was cut into a predetermined size (sizing), and pressure-bonded to both sides of a copper mesh to produce an air electrode 13. Next, each of the air electrodes 13 and the metal electrode 15 made of a magnesium alloy was used to fabricate the air battery 10, and a polarization test by discharge was performed. The test results are shown in FIG. In FIG. 2, the horizontal axis represents current density (mA / square centimeter), and the vertical axis represents battery voltage (V).

As shown in FIG. 2, Examples 1-6 showed the favorable characteristic compared with Comparative Examples 1-3. This indicates that Examples 1 to 6 can obtain a sufficient effect with a small amount of catalyst compared to Comparative Examples 1 to 3.
Moreover, although the tendency which a performance improves further is seen, so that the frequency | count of baking from impregnation increases, the difference of 5 times and 7 times is small, and it is thought that the frequency can improve a performance efficiently up to 5 times.
As for the comparative example, compared with Comparative Example 1 containing no manganese catalyst, Comparative Example 3 in which the catalyst was deposited on the carbon surface and Comparative Example 2 in which the manganese dioxide powder was simply added showed some improvement in polarization. However, a sufficient effect has not been obtained.

  According to the present embodiment, the carbon powder as the conductive material is fixed by the polymer binder (PTFE, PP) in the first catalyst sheet as the sheet member. Then, a series of steps of impregnating, drying, and heat-treating the first catalyst sheet with the solution of the manganese catalyst precursor is performed, so that a manganese oxide-based catalyst is deposited on the conductive material and the binder surface. By repeating this series of steps one or more times, a sufficient amount of catalyst is supported inside the sheet. As a result, a conductive matrix made of carbon carrying a catalyst as a reaction field in the sheet is formed. Therefore, the movement of electrons in the sheet is facilitated, and the performance of the air electrode 13 composed of the sheet and the current collector is dramatically improved.

Further, the inventors have confirmed that when using manganese nitrate as in Examples 1 and 2, manganese dioxide can be obtained if the heat treatment temperature is about 120 ° C. or higher. In Examples 1 and 2, decomposition of PTFE can be avoided by performing heat treatment at a relatively low temperature (120 ° C.) as long as the catalyst can be deposited and supported.
In Example 6 using manganese acetate, heat treatment is performed at 120 ° C. and 200 ° C. Even at 200 ° C., it is sufficiently lower than the melting point of PTFE (327 ° C.), so it is possible to avoid the decomposition of PTFE.
The temperature of the heat treatment may be any temperature that avoids the decomposition of PTFE, and is preferably 320 ° C. or lower from the viewpoint of considering a temperature rise due to reaction heat. More preferably, the temperature is 120 ° C. or higher and 280 ° C. or lower. Note that the heat treatment time may be appropriately adjusted according to the type of binder and the heat treatment temperature.

In addition, the thermal decomposition reaction can be promoted because the heat treatment is performed at atmospheric pressure and at a temperature at which the catalyst is obtained in the presence of air. Therefore, an inexpensive manganese-based catalyst can be operated efficiently, and an inexpensive and high-performance air battery 10 can be obtained. In particular, when an aqueous manganese nitrate solution is used as the manganese catalyst precursor solution, thermal decomposition as shown in the chemical formula (formula (1)) occurs near 120 ° C., so the heat treatment temperature is set to 120 ° C. or higher, and the melting point is When the organic binder which is the above polymer binder is used, the manganese oxide catalyst can be deposited without causing destruction of the sheet.
Mn (NO ₃ ) ₂ → MnO ₂ +2 (NO ₂ ) (1)

As the manganese catalyst precursor, it is necessary to consider the combination of the processing temperature and the melting point of the organic binder. For example, manganese (II) nitrate, manganese (II) acetate, or manganese bis (II) acetate can be used. The organic binder is not limited to a fluorine-based resin such as PTFE and a polyolefin-based resin such as polypropylene, and a polyimide resin or an aramid resin can be used.
In addition, since the organic binder has thermoplasticity, sintering between the binders occurs when the heat treatment temperature is around these sintering temperatures, and the effect of increasing the mechanical strength of the catalyst sheet can be obtained.

Thus, the catalyst sheet of this embodiment knead | mixes the carbon powder which is a electrically conductive material, an organic substance binder, and water, Then, it shape | molds and dries and produces a 1st catalyst sheet (sheet | seat member), It is obtained by performing a series of steps of impregnating, drying, and heat-treating a solution of the manganese catalyst precursor once or a plurality of times. Thereby, it becomes easy to manufacture the catalyst sheet which can smooth an electron transfer by the structure using a manganese catalyst.
In addition, the amount of catalyst supported on the catalyst sheet can be easily adjusted by the number of series of steps of impregnating, drying, and heat-treating the manganese catalyst precursor solution.

In addition, since the catalyst sheet is heat-treated at atmospheric pressure and at a temperature at which the catalyst is obtained in the presence of air, the thermal decomposition reaction during sheet production can be facilitated.
In addition, as shown in Examples 1 to 5, since an aqueous manganese nitrate solution is used as the manganese catalyst precursor solution, the manganese oxide catalyst can be deposited at a relatively low temperature. Therefore, it becomes easy to select an organic binder that is a polymer binder having a melting point equal to or higher than the above temperature.
Furthermore, since a polymer dispersion having a melting point higher than the temperature at the time of the heat treatment is used as the organic binder, decomposition of the organic binder can be avoided and destruction of the sheet can be avoided. Moreover, the mechanical strength of the catalyst sheet can be increased by using a thermoplastic resin for the organic binder.

  Moreover, since the air electrode 13 is obtained by pressure-bonding the catalyst sheet manufactured by the above manufacturing method to the current collector, it becomes easy to manufacture the air electrode 13 that can facilitate the electron transfer with the configuration using the manganese catalyst. . Moreover, the manufacturing method of this embodiment can be manufactured without applying a local stress (for example, shearing force) to the catalyst sheet and the air electrode 13, and it is easy to stabilize the quality of the catalyst sheet and the air electrode 13. Become.

Next, another embodiment will be described.
In the above-described embodiment, the first catalyst sheet was prepared by kneading carbon powder as an electrically conductive material, an organic binder, and water, followed by molding and drying. Not limited to this, the sheet member may be produced by kneading a conductive material, manganese dioxide powder, and an organic binder in a dispersion medium, followed by molding and drying.
In addition, the point which performs the series of processes which impregnates the solution of a manganese catalyst precursor to the produced sheet member, drys, and heat-processes once or several times is the same as the said embodiment.

4). (Example)
Examples and comparative examples will be described. Each Example and Comparative Example are the same except that the catalyst sheet is different, and the catalyst sheet will be described below. Information on each catalyst sheet is shown in Table 2.

KB, electrolytic manganese dioxide powder as a conductive material, PTFE as an organic binder and water (dispersion medium) were kneaded, and continued until fibrillation of PTFE occurred and the viscosity change was stabilized, thereby preparing a paste having a predetermined viscosity. This paste was sandwiched between PET films, and a sheet member having a predetermined thickness was produced by a roller press set to a roll gap of 1 mm. This sheet member was dried and fired at 270 ° C. for 30 minutes to prepare a catalyst sheet containing no manganese catalyst (hereinafter referred to as “second catalyst sheet”). The composition of the second catalyst sheet was electrolytic manganese dioxide: KB: PTFE = 8: 52: 40.
Here, as the electrolytic manganese dioxide powder, dry cell grade electrolytic manganese dioxide (EMD) powder was used. EMD is mainly composed of γ-type manganese dioxide and is granular.

4.1 (Example 1A)
After an appropriate amount of ethanol was sprayed on the first catalyst sheet, the first catalyst sheet was placed in a 0.5 M aqueous manganese nitrate solution in which manganese (II) nitrate hexahydrate was dissolved, and the aqueous manganese nitrate solution was vacuum impregnated in the sheet. After removing the excess liquid, drying was performed at 80 ° C. for 2 hours with a dryer, and then heat treatment was performed at 200 ° C. for 1 hour as a baking treatment.
The above heat treatment was carried out in the presence of air and in an atmosphere of atmospheric pressure. 200 ° C. is the temperature at which the catalyst is obtained. By this heat treatment, manganese dioxide is precipitated by thermal decomposition of manganese (II) nitrate, and fixation and loading of manganese dioxide are completed. The total amount of manganese dioxide added is 10 mass% with respect to the total weight of the catalyst sheet.
The precipitated manganese dioxide contains α-type and β-type, and the first catalyst sheet contains γ-type manganese dioxide. Therefore, α-type, β-type, and γ-type manganese dioxide are mixed in the catalyst sheet.

4.2 (Example 2A)
After an appropriate amount of ethanol was sprayed on the second catalyst sheet, the second catalyst sheet was placed in a 0.5 M aqueous manganese nitrate solution in which manganese (II) nitrate hexahydrate was dissolved, and the aqueous manganese nitrate solution was vacuum impregnated in the sheet. After removing the excess liquid, drying was performed at 80 ° C. for 2 hours with a dryer, and then heat treatment was performed at 200 ° C. for 1 hour as a baking treatment. Furthermore, a series of treatments including the above impregnation, drying and heat treatment was performed on the catalyst sheet after firing three times in total. The total amount of manganese dioxide added is 14 mass% with respect to the total weight of the catalyst sheet.
The heat treatment of Example 2A, and Examples 3A and 4A and Comparative Examples described below are performed in the presence of air and in an atmosphere of atmospheric pressure, as in Example 1A.

4.3 (Example 3A)
After an appropriate amount of ethanol was sprayed on the second catalyst sheet, the second catalyst sheet was placed in a 0.5 M aqueous manganese nitrate solution in which manganese (II) nitrate hexahydrate was dissolved, and the aqueous manganese nitrate solution was vacuum impregnated in the sheet. After removing the excess liquid, drying was performed at 80 ° C. for 2 hours with a dryer, and then heat treatment was performed at 200 ° C. for 1 hour as a baking treatment. Furthermore, a series of treatments consisting of the above impregnation, drying and heat treatment was performed on the calcined catalyst sheet 5 times in total. The total amount of manganese dioxide added is 17 mass% with respect to the total weight of the catalyst sheet.

4.4 (Example 4A)
After an appropriate amount of ethanol was sprayed on the second catalyst sheet, the second catalyst sheet was placed in a 0.5 M aqueous manganese nitrate solution in which manganese (II) nitrate hexahydrate was dissolved, and the aqueous manganese nitrate solution was vacuum impregnated in the sheet. After removing the excess liquid, drying was performed at 80 ° C. for 2 hours with a dryer, and then heat treatment was performed at 200 ° C. for 1 hour as a baking treatment. Furthermore, a series of treatments consisting of the above impregnation, drying and heat treatment were performed on the catalyst sheet after calcination a total of 7 times. The total amount of manganese dioxide added is 20 mass% with respect to the total weight of the catalyst sheet.

5. (Comparative example)
5.1 (Comparative Example 1A)
KB as an electrically conductive material and PTFE as an organic binder and water were kneaded, and fibrillation of PTFE occurred and continued until the viscosity change was stabilized, thereby preparing a paste (electric material slurry) having a predetermined viscosity. This paste was sandwiched between PET films, and a sheet member having a predetermined thickness was produced by a roller press set to a roll gap of 1 mm. This sheet member was dried and fired at 200 ° C. for 1 hour to prepare a catalyst sheet containing no manganese catalyst. The composition in the catalyst sheet was KB: PTFE = 60: 40.

5.2 (Comparative Example 2A)
KB, electrolytic manganese dioxide powder as the conductive material, PTFE and water as the organic binder were kneaded and continued until fibrillation of PTFE occurred and the viscosity change was stabilized, thereby preparing a paste (electric material slurry) with a predetermined viscosity. This paste was sandwiched between PET films, and a sheet member having a predetermined thickness was produced by a roller press set to a roll gap of 1 mm. This sheet member was dried and fired at 270 degrees for 30 minutes to prepare a catalyst sheet not containing a manganese catalyst. The composition in the catalyst sheet was electrolytic manganese dioxide: KB: PTFE = 10: 50: 40.

5.3 (Comparative Example 3A)
KB, electrolytic manganese dioxide powder as the conductive material, PTFE and water as the organic binder were kneaded and continued until fibrillation of PTFE occurred and the viscosity change was stabilized, thereby preparing a paste (electric material slurry) with a predetermined viscosity. This paste was sandwiched between PET films, and a sheet member having a predetermined thickness was produced by a roller press set to a roll gap of 1 mm. This sheet member was dried and fired at 270 degrees for 30 minutes to prepare a catalyst sheet not containing a manganese catalyst. The composition in the catalyst sheet was electrolytic manganese dioxide: KB: PTFE = 30: 30: 40.

5.4 (Comparative Example 4A)
As a conductive material, KB and a 1M manganese nitrate aqueous solution in which manganese (II) nitrate hexahydrate is dissolved are kneaded so that the ratio of KB and manganese dioxide powder is 5: 1. Dried for 24 hours. Then, after heat-processing at 200 degreeC for 1 hour, it grind | pulverized and the catalyst powder by which manganese dioxide was carry | supported on the surface of KB was prepared. A catalyst sheet was prepared by kneading PTFE and water as the catalyst powder and organic binder at a ratio of PTFE of 6: 4 as the catalyst powder and organic binder. Finally, heat treatment (baking treatment) was performed at 200 ° C. for 1 hour.
Thus, Comparative Example 4A produced a catalyst sheet containing 10% manganese dioxide by mixing the powder in which manganese dioxide was deposited and supported on the carbon surface.

6). (Evaluation test)
Each catalyst sheet was cut into a predetermined size (sizing), and pressure-bonded to both sides of a copper mesh serving as a current collector to produce an air electrode 13. Moreover, the air electrode 13 was produced by pressure bonding the catalyst sheet of Example 1A on one side of the copper mesh and the catalyst sheet not containing the metal catalyst of Comparative Example 1A on the other side.
Next, each of the air electrodes 13 and the metal electrode 15 made of a magnesium alloy was used to fabricate the air battery 10, and a polarization test by discharge was performed. The specifications of the air electrode 13 of each air battery 10 are shown in Table 3, and the test results are shown in FIG.

As shown in FIG. 3, the batteries 1 to 4 using the catalyst sheets according to Examples 1A to 4A show better results than the batteries 5 to 8 using the catalyst sheets according to Comparative Examples 1A to 4A. It was. This has shown that Example 1A-4A has acquired sufficient effect with the small catalyst amount compared with Comparative Example 1A-4A.
In general, EMD requires an addition of several tens of percent in order to obtain sufficient catalytic activity. The reason for this is that, simply by adding EMD, each EMD particle is only in contact with carbon independently, and it is considered that the electron transfer from the reaction field on the catalyst surface is not smooth.
On the other hand, in Examples 1A to 4A, as shown in Table 2, sufficient effects are obtained regardless of the total manganese dioxide content in the range of 10% to 20%. That is, in this embodiment, EMD is used, and the electron transfer in the sheet can be facilitated while suppressing the total addition amount of manganese dioxide, which makes it easy to obtain a high-performance air electrode 13.

Moreover, although the tendency which a performance improves further is seen, so that there are many frequency | counts of baking from an impregnation, the difference of 3 times and 7 times is small, and the frequency | count can be considered as the range which can improve a performance efficiently up to 3 times.
The battery 9 shown in FIG. 3 uses an air electrode 13 in which a catalyst sheet of Example 1A is bonded on the electrolyte side and a catalyst sheet not containing the metal catalyst of Comparative Example 1A is pressed on the air side. This battery 9 has obtained characteristics close to those of Example 1A and is better than Comparative Examples 1A to 4A. Thus, by adopting a catalyst sheet with a small amount of catalyst on the air side, it becomes easy to ensure good characteristics with a smaller amount of catalyst.

  As for the comparative example, compared with Comparative Example 1 containing no manganese catalyst, a battery 8 (Comparative Example 4A) in which the catalyst is deposited and supported on the carbon surface, a battery 6 (Comparative Example 2A) in which manganese dioxide powder is simply added, and The battery 7 (Comparative Example 3A) showed some decrease in polarization, but a sufficient effect was not obtained.

As described above, the catalyst sheet of the present embodiment is kneaded with a conductive material, an organic binder, and water as a dispersion medium, and then molded and dried to produce a catalyst sheet (sheet member). It is obtained by performing a series of steps of impregnating, drying, and heat-treating a solution of the manganese catalyst precursor once or a plurality of times. Thereby, it is possible to facilitate the electron transfer with the structure using the manganese catalyst while using the manganese dioxide powder, to improve the polarization characteristics, and to easily manufacture an inexpensive catalyst sheet.
Further, it is possible to obtain the above-described various effects that the amount of catalyst supported on the catalyst sheet can be easily adjusted by the number of series of steps of impregnating, drying, and heat-treating the manganese catalyst precursor solution. .
In addition, the catalyst sheet is produced by kneading a carbon powder, which is a conductive material, and an organic binder with water, followed by molding and drying. Therefore, a sheet in which moisture permeation is suppressed by the polymer dispersion used in the organic binder is used. Can be obtained.

In addition, since electrolytic manganese dioxide is used for the manganese dioxide powder, the performance improvement as a catalyst sheet can be achieved as compared with the case where EMD is simply added while using electrolytic manganese dioxide (EMD) used as the positive electrode active material of the dry battery. Is possible.
It is also possible to adjust the amount of catalyst supported on the catalyst sheet by adjusting the amount of manganese dioxide powder.

  In addition, although the case where electrolytic manganese dioxide was used for the manganese dioxide powder was described, the present invention is not limited thereto, and manganese dioxide powder other than electrolytic manganese dioxide may be used. Moreover, although the case where water was used for the dispersion medium was illustrated, a mixture with water or a dispersion medium other than water may be used.

  The present invention is not limited to the above-described embodiments, and various modifications and changes can be made based on the technical idea of the present invention. For example, each catalyst sheet described above can be used for the air electrode of various air batteries. Moreover, you may use each catalyst sheet for the electrode plates of batteries other than an air battery.

DESCRIPTION OF SYMBOLS 10 Air battery 11 Exterior body 11A Holding member 11B Support member 11K Opening part 13 Air electrode 15 Metal electrode

Claims (7)

In the manufacturing method of the catalyst sheet used for the electrode of the battery,
After a conductive material, an organic binder and water are kneaded, a sheet member is formed by drying, and a series of steps of impregnating, drying, and heat treating the sheet member with a solution of a manganese catalyst precursor is performed once or plural times. A method for producing a catalyst sheet, characterized in that a catalyst sheet carrying a target amount of catalyst is obtained by performing the process once.   2. The method for producing a catalyst sheet according to claim 1, wherein the sheet member is prepared by kneading the conductive material, manganese dioxide powder, and the organic binder with water, and then molding and drying. 3.   The method for producing a catalyst sheet according to claim 1, wherein an aqueous manganese nitrate solution is used as the aqueous solution of the manganese catalyst precursor.   The method for producing a catalyst sheet according to claim 2, wherein electrolytic manganese dioxide is used as the manganese dioxide powder.   The method for producing a catalyst sheet according to any one of claims 1 to 4, wherein a polymer dispersion having a melting point higher than a temperature at the time of the heat treatment is used as the organic binder. In the manufacturing method of the air electrode used for the air battery,
After a conductive material, an organic binder and water are kneaded, a sheet member is formed by drying, and a series of steps of impregnating, drying, and heat treating the sheet member with a solution of a manganese catalyst precursor is performed once or plural times. A method for producing an air electrode, comprising: obtaining a catalyst sheet carrying a desired amount of catalyst by performing the process once, and pressing the catalyst sheet on a current collector.   The method for producing an air electrode according to claim 6, wherein the sheet member is manufactured by kneading the conductive material, manganese dioxide powder, and the organic binder with water, and then molding and drying.

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