JP7017354B2 - Sheet air battery and patch - Google Patents

Description

The present invention relates to a highly productive sheet-shaped air battery and a patch including the sheet-shaped air battery.

An air battery having a positive electrode consisting of an air electrode catalyzed by manganese dioxide or carbon and a negative electrode using metal particles such as zinc particles such as zinc particles and zinc alloy particles as an active material has been used as a power source for hearing aids for many years. Has been done.

This type of battery is generally a button-shaped battery that uses a metal can for the exterior body, and commercially available batteries have a bottom surface on the positive electrode side for taking in air (oxygen) inside. One to several air holes are formed with a diameter of about 0.2 to 0.5 mm.

In addition, a sheet-like battery using an exterior body made of a resin film, such as a laminated film obtained by laminating aluminum and a thermoplastic resin, has been proposed to give flexibility to the shape of the battery. It is disclosed that an air battery having excellent discharge characteristics can be configured (Patent Document 1).

By the way, recently, various applications for body sensors such as body temperature patches and power supplies for speed sensors for golf heads have been developed by taking advantage of the degree of freedom in the shape of the sheet-shaped air battery. .. Further, improvements in various characteristics of the sheet-shaped air battery have been attempted so that it can be preferably applied to such applications.

Under such circumstances, the sheet-shaped air battery is required to be manufactured at a lower cost, and in response to this, there is a demand for improvement in productivity.

In a sheet-air battery, for example, as described in Patent Document 1, a positive electrode having a catalyst layer containing a catalyst formed on the surface of a current collector, a metal powder, an electrolytic solution, and a polymer for gelation are used. A negative electrode in which the included gel-like negative electrode is brought into contact with the current collector is generally used. Further, the positive electrode and the negative electrode are provided with external terminals for electrically connecting to the equipment in which the battery is used, such as by being welded to the current collectors thereof. As described above, the positive electrode and the negative electrode have many manufacturing processes, which are one of the factors that impair the productivity of the sheet-shaped air battery.

Japanese Unexamined Patent Publication No. 2004-288571

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a sheet-shaped air battery having excellent productivity and a patch provided with the sheet-shaped air battery.

In the sheet-shaped air battery of the present invention that has achieved the above object, a positive electrode, a negative electrode, a separator and an electrolyte are housed in a sheet-like exterior body, and the positive electrode has a porous conductive base material and is porous. The conductive conductive base material has a main body portion and a terminal portion whose at least a part is exposed to the outside of the sheet-like exterior body, the negative electrode has a metal foil, and the metal foil has a main body portion. It is characterized by having a terminal portion exposed to at least a part of the outside of the sheet-shaped exterior body.

Further, the patch of the present invention is wearable on the body and is provided with the sheet-shaped air battery of the present invention as a power source.

According to the present invention, it is possible to provide a sheet-shaped air battery having excellent storage characteristics and a patch provided with the sheet-shaped air battery.

It is a top view schematically showing an example of the sheet-shaped air battery of this invention. FIG. 1 is a cross-sectional view taken along the line II of FIG. It is a top view schematically showing an example of the positive electrode which concerns on the sheet-shaped air battery of this invention. It is a top view schematically showing an example of the negative electrode which concerns on the sheet-shaped air battery of this invention. It is a top view schematically showing another example of the sheet-shaped air battery of this invention. It is explanatory drawing which shows an example of the assembling method of the sheet-shaped air battery of this invention.

1 and 2 schematically show an example of the sheet-shaped air battery of the present invention. FIG. 1 is a plan view of a sheet-shaped air battery, and FIG. 2 is a sectional view taken along line I-I of FIG.

As shown in FIG. 2, in the sheet-shaped air battery 1, the positive electrode 20, the separator 40, the negative electrode 30, and an electrolyte (not shown) are housed in the sheet-shaped exterior body 60. The dotted line in FIG. 1 represents the size of the positive electrode 20 housed in the sheet-shaped exterior body 60 (the size of the wide main body portion excluding the terminal portion).

The terminal portion 20b of the positive electrode 20 and the external terminal 30b of the negative electrode 30 project from the upper side of the sheet-shaped exterior body 60 in the drawing. These terminal portions 20b and 30b are used as external terminals for electrically connecting the sheet-shaped air battery and the applicable device.

The sheet-shaped exterior body 60 is provided with a plurality of air holes 61 for taking air into the positive electrode on one side on the side where the positive electrode 20 is arranged, and the air holes 61 are provided on the sheet-shaped exterior body 60 side of the positive electrode 20. A water-repellent film 50 is arranged to prevent leakage of the electrolyte from the water-repellent film 50.

FIG. 3 shows a plan view simulating a positive electrode related to a sheet-shaped air battery. The positive electrode 20 has a porous conductive base material, and the porous conductive base material has a main body portion 20a and a terminal portion 20b whose at least a part is exposed to the outside of the sheet-like exterior body. .. That is, a part of one porous conductive base material constitutes the terminal portion 20b, and the other main portion constitutes the main body portion 20a.

By forming a common member (porous conductive base material) between the main body portion 20a that functions as a current collector of the positive electrode 20 and the terminal portion 20b that is responsible for conduction to the outside, for example, a lead for an external terminal is used. Since there is no need to weld the body (tab) or the like, the productivity can be increased, and the productivity of the sheet-shaped air battery can be improved.

The portion of the porous conductive substrate that constitutes the terminal portion 20b may be made non-porous by compression.

The porous conductive base material may be made of a metal member such as a mesh such as nickel or stainless steel, a foam, a punching base material, or an expanded base material, but by using a carbon member, the main body portion 20a Since the porous conductive base material constituting the above functions also as a catalyst, it is not necessary to separately support a catalyst on the porous conductive base material of the main body 20a, and the productivity of the sheet-shaped air battery can be further improved. ..

When the porous conductive base material is made of carbon, for example, a porous carbon sheet made of fibrous carbon such as carbon paper, carbon cloth, and carbon felt can be preferably used. These sheets may have a single-layer structure, may have a multi-layer structure in which carbon papers, carbon cloths, and carbon felts are laminated, and may be two of carbon paper, carbon cloth, and carbon felt. The above may be a laminated multi-layered structure.

The fiber diameter of the fibrous carbon constituting the sheet is usually preferably 2 to 30 μm in consideration of the catalytic function and conductivity.

The thickness of the sheet made of fibrous carbon is preferably 0.5 mm or less. The sheet-shaped air battery is often in a thin form, but if the sheet constituting the positive electrode is too thick, the thickness of the entire positive electrode also increases, and it may be difficult to form a thin battery. The lower limit of the thickness of the sheet made of fibrous carbon is usually 0.05 mm in consideration of handleability, availability, sufficient battery reaction at the positive electrode, and securing of a current collecting function.

The porosity of the sheet made of fibrous carbon is preferably 50% or more and 95% or less from the viewpoint of ensuring good air permeability and sufficient strength.

For the sheet made of fibrous carbon, a commercially available product that satisfies the above physical characteristics may be selected and used.

When a positive electrode is formed by using the sheet made of fibrous carbon as a porous carbon sheet, the positive electrode can be manufactured only by punching these sheets into a desired shape, so that the productivity of the positive electrode is further improved. ..

On the other hand, it is also possible to separately support a catalyst on a portion constituting the main body of the sheet made of fibrous carbon. That is, by supporting a material normally used as a catalyst for an air battery on the surface or inside of the porous conductive base material constituting the main body, the productivity of the positive electrode is slightly inferior, but the main body Since the catalyst function is improved, higher battery characteristics can be ensured.

When the porous conductive base material is made of a metal member, the catalytic function is inferior to that of the porous carbon sheet, except when the porous conductive base material is made of a noble metal such as platinum. Therefore, the porous conductive base material is inferior to the porous carbon sheet. It is desirable to separately support a catalyst on the portion constituting the main body portion.

As the catalyst to be supported on the main body of the porous conductive substrate, a catalyst usually used as a catalyst for an air cell can be used, for example, silver, platinum group metal or an alloy thereof, transition metal, Pt / IrO ₂ Platinum / metal oxides such as La _1-x Ca _x CoO ₃ , perovskite oxides such as WC, carbides such as WC, nitrides such as Mn ₄ N, manganese oxides such as manganese dioxide and Mn ₃ O ₄ , carbon [ Graphite, carbon black (acetylene black, ketjen black, channel black, furnace black, lamp black, thermal black, etc.), charcoal, activated charcoal, etc.], etc.], etc. may be used, and only one of these may be used. More than a seed may be used.

When a carbon catalyst is used, the specific surface area of carbon is preferably 200 m ² / g or more, more preferably 300 m ² / g or more, and more preferably 500 m ² from the viewpoint of further enhancing the reactivity of the positive electrode. It is more preferably / g or more. The specific surface area of carbon referred to in the present specification is a value obtained by the BET method according to JIS K 6217. For example, a specific surface area measuring device by a nitrogen adsorption method (“Macsorb HM model-1201” manufactured by Muntech) can be used. Can be measured using. The upper limit of the specific surface area of carbon is usually about 2000 m ² / g.

When the catalyst is supported on the surface or inside of the porous conductive substrate, a method such as applying a composition composed of a binder or the like to the porous conductive substrate to form a catalyst-containing layer is usually used. Just do it.

Examples of the binder contained in the catalyst-containing layer include a copolymer of PVDF, PTFE and vinylidene fluoride, and a copolymer of tetrafluoroethylene [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.] and other fluororesin binders. Among these, a tetrafluoroethylene polymer (PTFE) or a copolymer is preferable, and PTFE is more preferable. The binder content in the catalyst-containing layer is preferably 3 to 50% by mass.

The catalyst-containing layer can be formed by mixing a catalyst, a binder, or the like with a solvent such as water, rolling it with a roll, and bringing it into close contact with the sheet or the like as a base material. Further, a catalyst-containing layer forming composition (slurry, paste, etc.) prepared by dispersing a catalyst and a binder to be used as needed in water or an organic solvent is applied to the surface of the sheet as a base material. After drying, the catalyst-containing layer can also be formed through a step of performing a press treatment such as a calendar treatment, if necessary.

The porous conductive base material on which the catalyst is supported on the surface or the inside of the main body can be punched into a desired shape to form a positive electrode.

FIG. 4 shows a plan view simulating the negative electrode of the sheet-shaped air battery. The negative electrode 30 has a metal foil, and the metal foil has a main body portion 30a and a terminal portion whose at least a part is exposed to the outside of the sheet-like exterior body. That is, a part of one metal foil constitutes the terminal portion 30b, and the other main portion constitutes the main body portion 30a.

By forming a common member (metal foil) between the main body portion 30a that functions as the active material of the negative electrode and the terminal portion 30b that is responsible for conduction to the outside, for example, a lead body (tab) for an external terminal or the like can be formed. Since there is no need for welding and the process of preparing a negative electrode mixture containing metal particles as an active material is not required, the productivity can be increased, which in turn improves the productivity of the sheet-shaped air battery. Can be made to.

In addition, in order to improve the current collecting property of the negative electrode, a conductive paint such as carbon paste may be applied to the surface of the main body portion 30a which is the active material of the negative electrode and which does not face the positive electrode, and the negative electrode may be coated. The conductive paint may be applied to a portion of the sheet-like exterior body arranged on the side in contact with the main body portion 30a.

As the metal foil for forming the negative electrode, a foil containing a component that functions as a negative electrode active material is used. Specific examples thereof include zinc or zinc alloy foil, magnesium or magnesium alloy foil, aluminum or aluminum alloy foil, and the like. In the negative electrode formed from these metal foils, zinc, aluminum or magnesium acts as the negative electrode active material.

The alloy components in the zinc alloy foil include, for example, indium (for example, the content is 0.005 to 0.05% by mass), bismuth (for example, the content is 0.005 to 0.05% by mass), and aluminum. (For example, the content is 0.001 to 0.15% on a mass basis) and the like.

The alloy components in the magnesium alloy foil include, for example, calcium (for example, the content is 1 to 3% based on mass), manganese (for example, the content is 0.1 to 0.5% based on mass), and zinc (for example,). The content is 0.4 to 1% on a mass basis), aluminum (for example, the content is 8 to 10% on a mass basis), and the like.

Further, the alloy components in the aluminum alloy foil include, for example, zinc (for example, the content is 0.5 to 10% by mass), tin (for example, the content is 0.04 to 1.0% by mass), and gallium. (For example, the content is 0.003 to 1.0% by mass), silicon (for example, the content is 0.05% or less by mass), iron (for example, the content is 0.1% or less by mass), Examples thereof include magnesium (for example, the content is 0.1 to 2.0% by mass) and manganese (for example, the content is 0.01 to 0.5% by mass).

The thickness of the negative electrode (thickness of the metal foil constituting the negative electrode) is preferably 10 to 500 μm.

As the electrolyte of the sheet-shaped air battery, for example, an aqueous solution containing an electrolyte salt is used. The aqueous solution used as the electrolyte has a pH of preferably 3 or more, more preferably 5 or more, preferably less than 12, more preferably 10 or less, and less than 7. It is more preferable to have. By using an aqueous solution having such a pH, for example, a sheet-shaped air battery is discarded as compared with the case of using a high pH alkaline aqueous solution (about pH 14), which is a strong alkali generally used for an air battery. Even if the electrolyte adheres to the human body due to damage during time or use, problems are unlikely to occur, high safety can be ensured, and the burden on the environment after disposal can be reduced.

The electrolyte salt to be dissolved in the aqueous solution used as an electrolyte includes chlorides such as sodium chloride, potassium chloride, magnesium chloride, calcium chloride, ammonium chloride and zinc chloride; hydroxides of alkali metals and alkaline earth metals (water). Sodium oxide, potassium hydroxide, magnesium hydroxide, etc.), acetate (sodium acetate, potassium acetate, magnesium acetate, etc.), nitrate (sodium nitrate, potassium nitrate, magnesium nitrate, etc.), sulfate (sodium sulfate, potassium sulfate, magnesium sulfate, etc.) Etc.), phosphates (sodium phosphate, potassium phosphate, magnesium phosphate, etc.), borates (sodium borate, potassium borate, magnesium borate, etc.), citrates (sodium citrate, potassium citrate, etc.) , Magnesium citrate, etc.), glutamate (sodium glutamate, potassium glutamate, magnesium glutamate, etc.); alkali metal hydrogen carbonate (sodium hydrogencarbonate, potassium hydrogencarbonate, etc.); alkali metal percarbonate (sodium percarbonate, hyper) Potassium carbonate and the like); compounds containing halogens such as fluoride; polyvalent carboxylic acids; and the like, and the aqueous solution may contain one or more of these electrolyte salts.

As the electrolyte salt, a salt of a strong acid selected from hydrochloric acid, sulfuric acid and nitric acid and a weak base represented by a hydroxide of a metal element such as ammonia, aluminum hydroxide and magnesium hydroxide is preferable, and an ammonium salt is preferable. Alternatively, it is more preferable to use a salt of a specific metal element. Specifically, at least one ion selected from Cl ⁻ , SO ^4-2- , HSO ₄ ⁻ and NO ₃ ⁻ _, and at least one selected from Al ion, Mg ion, Fe ion and ammonium ion. Salts with ions are more preferred, ammonium salts such as ammonium sulfate, ammonium hydrogensulfate [(NH ₄ ) HSO ₄ ], ammonium chloride, ammonium nitrate; aluminum salts such as aluminum sulfate, aluminum chloride, aluminum nitrate; magnesium sulfate, Magnesium salts such as magnesium chloride, magnesium chloride hydroxide [MgCl (OH)], magnesium nitrate; iron sulfate (II), ammonium iron sulfate (II) [(NH ₄ ) ₂ Fe (SO ₄ ) ₂ ], iron sulfate (III) ), Iron salts such as iron (II) chloride and iron (II) nitrate; and the like are exemplified.

An electrolyte composed of an aqueous solution containing a salt of a strong acid and a weak base as exemplified above corrodes a metal or an alloy which is a negative electrode active material as compared with an electrolyte containing a salt of a strong acid such as sodium chloride and a strong base. The action is relatively small. Further, among the salts of strong acids, the electrolyte containing a salt of a metal element selected from Al, Mg and Fe or an ammonium salt has a relatively high conductivity as compared with, for example, an aqueous solution of zinc chloride. Therefore, as a salt of a strong acid and a weak base, it is selected from at least one ion selected from ^Cl- , SO ^4-2- , _{HSO 4-} ^and NO _3- ^, and Al ion, Mg ion, Fe ion and ammonium ion. When an electrolyte composed of an aqueous solution containing a salt with at least one kind of ion is used, the discharge characteristics of the sheet-shaped air battery can be further enhanced.

However, the salt of Cl ^- ion and Fe ³⁺ ion [iron (III) chloride] has a stronger effect of corroding the metal material, which is the negative electrode active material, than the salt made by combining other ions, so iron chloride (iron chloride (III)] It is preferable to use a salt other than III), and it is more preferable to use an ammonium salt because it has a lower effect of corroding the metal material which is the negative electrode active material.

Further, among the salts of the strong acid and the weak base, perchlorate causes a risk of combustion or explosion due to heating or impact, and therefore, from the viewpoint of environmental load and safety at the time of disposal, it is contained in the aqueous solution. It is preferable that the amount of perchlorate ion is small (preferably less than 100 ppm, more preferably less than 10 ppm) even if it is not allowed or contained.

Of the salts of the strong acid and the weak base, heavy metal salts (excluding iron salts) typified by zinc chloride and copper sulfate are often harmful, so they are environmentally burdensome and safe at the time of disposal. From the viewpoint of the above, it is preferable that the amount of heavy metal ions excluding iron ions is small (preferably less than 100 ppm, more preferably less than 10 ppm) even if it is not contained in the aqueous solution or is contained.

Further, it is preferable that the aqueous solution that can be used as an electrolyte contains a water-soluble high boiling point solvent having a boiling point of 150 ° C. or higher as a solvent together with water. In an air battery, as the capacity decreases after discharging, the voltage decreases accordingly, but in the latter stage of discharging when the capacity decreases, the fluctuation tends to increase in addition to the decrease in voltage. However, when the aqueous solution contains a water-soluble high boiling point solvent, it is possible to suppress such fluctuations in voltage in the latter stage of discharge to obtain a sheet-shaped air battery having better discharge characteristics.

Further, as shown in FIGS. 1 and 2, the air battery has an air hole for introducing air into the positive electrode in the outer body, but the water in the electrolyte (electrolyte solution) volatilizes in the outer body. The composition of the electrolyte is likely to fluctuate due to dissipation through the air holes of the above, which may deteriorate the discharge characteristics. However, when the aqueous solution used as the electrolyte contains a water-soluble high boiling point solvent, the volatilization of water from the electrolyte is suppressed, so that the deterioration of the discharge characteristics due to the composition fluctuation of the electrolyte as described above is suppressed. It is also possible to further improve the storage characteristics of the sheet-shaped air battery.

The upper limit of the boiling point of the water-soluble high boiling point solvent is usually 320 ° C.

From the viewpoint of maintaining the discharge characteristics of the sheet-shaped air battery better, it is desirable that the water-soluble high boiling point solvent has a high surface tension and relative permittivity. In a sheet-air battery, the positive electrode (catalyst-containing layer) needs to come into contact with air during discharge, but if the surface tension of the water-soluble high boiling point solvent in the electrolytic solution is low, the surface of the catalyst-containing layer of the positive electrode , The proportion of the part covered with electrolyte that makes it difficult to come into contact with air becomes too large, and the discharge characteristics may deteriorate. However, by using a water-soluble high boiling point solvent with high surface tension, such a problem can be avoided. be able to.

In addition, since organic solvents usually have a lower relative permittivity than water, if an electrolyte is prepared in combination with water, the ionic conductivity will be lower than when only water is used, and the discharge characteristics of the battery will be reduced. However, the occurrence of such a problem can be suppressed by using a water-soluble high boiling point solvent having a high relative permittivity.

Specifically, the surface tension of the water-soluble high boiling point solvent is preferably 30 mN / m or more. The upper limit of the surface tension of the water-soluble high boiling point solvent is usually 70 mN / m. The surface tension of the water-soluble high boiling point solvent referred to in the present specification is a value measured by the Wilhelmy method using a commercially available device (for example, "CBVP-Z" manufactured by Kyowa Interface Science Co., Ltd.).

Further, the relative permittivity of the water-soluble high boiling point solvent is preferably 30 or more. The upper limit of the relative permittivity of the water-soluble high boiling point solvent is usually 65. The relative permittivity of the water-soluble high boiling point solvent referred to in the present specification is a value obtained from the permittivity measured by using "Prejon LCR Meter HP4284" manufactured by HEWLETT PACKARD.

Specific examples of the water-soluble high boiling point solvent suitable for the electrolyte include ethylene glycol (boiling point 197 ° C., surface tension 48 mN / m, relative permittivity 39) and propylene glycol (boiling point 188 ° C., surface tension 36 mN / m, relative permittivity 39). 32), polyhydric alcohols such as glycerin (boiling point 290 ° C., surface tension 63 mN / m, relative permittivity 43); polyethylene glycol (PEG; eg, boiling point 230 ° C., surface tension 43 mN / m, relative permittivity 35) and the like. Polyalkylene glycol (preferably having a molecular weight of 600 or less); and the like. As the electrolyte solution, only one of these water-soluble high boiling point solvents may be used, or two or more of them may be used in combination, but it is more preferable to use glycerin.

When a water-soluble high boiling point solvent is used, the content of the water-soluble high boiling point solvent in all the solvents of the aqueous solution is preferably 1% by mass or more, from the viewpoint of ensuring the effect of the use. More preferably, it is by mass or more. However, if the amount of the water-soluble high boiling point solvent in the aqueous solution is too large, the ionic conductivity of the aqueous solution may become too small and the battery characteristics may deteriorate. Therefore, the water solubility of the aqueous solution in all the solvents. The content of the high boiling point solvent is preferably 30% by mass or less, more preferably 20% by mass or less.

The concentration of the electrolyte salt in the aqueous solution may be, for example, a concentration that can adjust the conductivity of the aqueous solution to about 80 to 700 mS / cm, and is usually 5 to 50% by mass.

It is preferable that the indium compound is dissolved in the solvent (water or a mixed solvent of water and a water-soluble high boiling point solvent) in the aqueous solution used as an electrolyte. When the indium compound is dissolved in the aqueous solution, the generation of hydrogen gas in the battery can be satisfactorily suppressed.

Examples of the indium compound to be dissolved in the aqueous solution include indium hydroxide, indium oxide, indium sulfate, indium sulfide, indium nitrate, indium bromide, and indium chloride.

The concentration of the indium compound in the aqueous solution is preferably 0.005% or more, more preferably 0.01% or more, particularly preferably 0.05% or more, and particularly preferably 0.05% or more, based on the mass. It is preferably 1% or less, more preferably 0.5% or less, and particularly preferably 0.1% or less.

In addition to the above-mentioned components, various known additives may be added to the aqueous solution as needed, as long as the effects of the present invention are not impaired. For example, zinc oxide may be added in order to prevent corrosion (oxidation) of the metal material used for the negative electrode.

Further, the aqueous solution constituting the electrolyte may be gelled, and a gel-like electrolyte obtained by blending an aqueous solution containing an electrolyte salt with a pH of 3 or more and less than 12 and a thickener is used in a sheet-shaped air battery. It is also preferable to use it as an electrolyte. In this case as well, it is possible to suppress the fluctuation of the voltage in the latter stage of the discharge to further improve the discharge characteristics of the sheet-air battery, and since the volatilization of water from the gel-like electrolyte is suppressed, the discharge due to the composition fluctuation of the electrolyte is suppressed. It is possible to suppress the deterioration of the characteristics, and it is also possible to further improve the storage characteristics of the sheet-shaped air battery.

As the aqueous solution containing the electrolyte salt and having a pH of 3 or more and less than 12, which is related to the gel-like electrolyte, the same aqueous solution as the above-exemplified aqueous solution which can be used as the electrolyte of the sheet-shaped air battery can be used.

Thickeners for forming gel-like electrolytes include cellulose derivatives such as carboxymethyl cellulose (CMC) and carboxyethyl cellulose (CEC); polyalkylene glycols such as polyethylene glycol (PEG) (however, the molecular weight is 10,000 or more). (Preferably); polyvinylpyrrolidone; polyvinyl acetate; starch; guar gum; xanthan gum; sodium alginate; hyaluronic acid; gelatin; various synthetic polymers or natural polymers can be mentioned. For the formation of the gel-like electrolyte, only one of the above-mentioned thickeners may be used, or two or more of them may be used in combination. In addition, polyalkylene glycols such as PEG are generally marketed in a state where the molecular weight (average molecular weight) is specified, and the molecular weight of polyalkylene glycol as used herein means a nominal value of such a manufacturer. There is.

Among the above-mentioned thickeners, the electrolyte (electrolyte solution which is an aqueous solution of an electrolyte salt) has a high thickening effect, and a gel-like electrolyte having good properties can be more easily prepared. PEG having a molecular weight of 100,000 or more, preferably 5 million or less) is more preferable.

Since CMC is an anionic polymer and is easily affected by the coexistence of metal ions and salts, the thickening action of the electrolyte may be reduced. However, when the degree of etherification of CMC is high, it is not easily affected by metal ions and salts, and the thickening action of the electrolyte can be exhibited more satisfactorily. Specifically, the degree of etherification of CMC is preferably 0.9 or more, and more preferably 1.0 or more. The degree of etherification of CMC referred to here is a numerical value indicating how many carboxymethyl groups are ether-bonded with respect to one anhydrous glucose unit. The degree of etherification of CMC is preferably 1.6 or less.

Further, when a thickener having a functional group (-COOH, -COONa, etc.) consisting of a carboxyl group or a salt thereof, such as CMC, CEC, xanthan gum, and sodium alginate, is used as a gelation accelerator. It is preferable to add an acting polyvalent metal salt to the electrolyte. In this case, the gelation accelerator acts on the thickener to gel the electrolyte more satisfactorily, so that the formation of a gel-like electrolyte having good properties becomes easier.

The polyvalent metal salt that can be used as a gelation accelerator varies depending on the type of thickener used, but a divalent or trivalent metal ion salt is preferable, and a magnesium salt (such as magnesium sulfate) and a calcium salt (sulfuric acid) are preferable. Alkaline earth metal salts such as calcium); aluminum salts such as aluminum nitrate and aluminum sulfate; iron salts such as iron (II) chloride, iron (III) chloride and iron (III) sulfate; chromium salts such as chromium nitrate; etc. Can be mentioned. Among these, aluminum salts and iron salts are more preferable. For the formation of the gel electrolyte, it is desirable to use an aqueous solution with a pH of 3 or more and less than 12, thereby reducing the environmental load of the battery. However, when an aluminum salt or iron salt is used as the gelation accelerator. Can suppress the increase in environmental load due to this gelation accelerator.

Depending on the combination of the electrolyte salt and the thickener, the electrolyte salt itself acts as a gelation accelerator, making it impossible to form a uniform gel-like electrolyte, or producing a gel-like electrolyte having sufficient ionic conductivity. It may not be possible to form. In such a case, only a monovalent metal ion salt may be used as the electrolyte salt, a polyvalent metal ion salt and a monovalent metal ion salt may be used in combination, or an aqueous solution containing an electrolyte salt may be used. And an aqueous solution containing a thickener are prepared separately and then mixed to prepare an electrolyte, whereby the above-mentioned problem can be prevented from occurring. It is also preferable to use an ammonium salt as the electrolyte salt.

The blending amount of the thickener in the electrolyte is preferably 0.1% by mass or more, preferably 0.2% by mass or more, from the viewpoint of ensuring good ionic conductivity while making the electrolyte a good gel. It is more preferably 5% by mass or less, and more preferably 3% by mass or less.

Further, when the polyvalent metal salt which is a gelation accelerator is blended in the electrolyte, the blending amount of the polyvalent metal salt is the ratio of the thickener in terms of mass ratio from the viewpoint of exerting its action better. When it is 100, it is preferably 1 or more, and more preferably 2 or more. Further, even if the compounding amount of the polyvalent metal salt is increased, the effect is saturated. Therefore, the compounding amount of the polyvalent metal salt in the electrolyte is 30 or less when the ratio of the thickener is 100 by mass ratio. It is preferably 20 or less, and more preferably 20 or less.

When the electrolyte salt also serves as a gelation accelerator, the blending amount of the gelation accelerator may be set within a suitable concentration range of the above-mentioned electrolyte salt.

The aqueous solution containing an electrolyte salt to be used as an electrolyte can be prepared by adding necessary components (electrolyte salt, water-soluble high boiling point solvent used as needed, indium compound, etc.) to water and dissolving the solution. good.

Further, the gel-like electrolyte is prepared, for example, by dissolving a thickener and other components (indium compound, etc.) used as necessary in an aqueous solution containing a prepared electrolyte salt and having a pH of 3 or more and less than 12. Can be formed by. Further, when a water-soluble high boiling point solvent is used, for example, water and a water-soluble high boiling point solvent are mixed, the aqueous solution is prepared using this mixed solvent, and this is used for forming a gel electrolyte. Just do it.

Further, when a thickener having a functional group consisting of a carboxyl group or a salt thereof in the molecule and a polyvalent metal salt acting as a gelation accelerator are used for the gel electrolyte, the pH containing the electrolyte salt is used. It is preferable to form a gel-like electrolyte by a method of mixing an aqueous solution in which a thickener is further dissolved in an aqueous solution having a concentration of 3 or more and less than 12 and an aqueous solution in which a gelling accelerator (polyvalent metal salt) is dissolved. .. When such a preparation method is adopted, a gel-like electrolyte is formed better than a method of adding a thickener and a polyvalent metal salt to an aqueous solution containing an electrolyte salt and having a pH of 3 or more and less than 12. can do. Further, an aqueous solution containing an electrolyte salt and having a pH of 3 or more and less than 12 in which a thickener is further dissolved and an aqueous solution in which a gelation accelerator (polyvalent metal salt) is dissolved are each in the form of a battery sheet. It is particularly preferable to inject it into the outer body and mix the two in the sheet-like outer body because a gel-like electrolyte can be formed more efficiently and satisfactorily.

Examples of the separator for a sheet-type air battery include separators generally used in various batteries such as resin porous membranes (microporous membranes, non-woven films, etc.) and semipermeable membranes typified by cellophane films. Be done. From the viewpoint of preventing short circuits in the sheet-shaped air battery and improving the load characteristics, it is preferable to use a semipermeable membrane as the separator.

Examples of the resin constituting the separator made of a resin-made porous film include polyolefins such as polyethylene (PE), polypropylene (PP), and an ethylene-propylene copolymer.

In the case of a resin separator, the porosity is preferably 30 to 80%, and the thickness is preferably 10 to 100 μm.

When a semipermeable membrane such as a cellophane film is used as the separator, the separator may be composed of only the semipermeable membrane. However, since the semipermeable membrane has low strength, problems such as damage during battery assembly are likely to occur. Therefore, it is also recommended to configure the separator with a laminate in which a graft film composed of a specific polymer and a semipermeable membrane are laminated.

The graft polymer constituting the graft film has, for example, a form in which (meth) acrylic acid or a derivative thereof is graft-polymerized with a polyolefin (polyethylene, polypropylene, etc.) which is a stem polymer. However, the graft polymer may have the above-mentioned form, and may not be produced by a method of graft-polymerizing (meth) acrylic acid or a derivative thereof with polyolefin.

The (meth) acrylic acid or a derivative thereof constituting the graft polymer is represented by the following general formula (1). In the following general formula (1), R ¹ is H or CH ₃ , and R ² means a hydrophilic substituent such as H or NH ₄ , Na, K, Rb, and Cs.

The graft film and cellophane film described above have a function that the polymer itself constituting these films absorbs an electrolyte and permeates ions.

The graft polymer constituting the graft film preferably has a graft ratio of 160% or more as defined by the following formula (2). Since there is a correlation between the graft ratio of the graft polymer and the electrical resistance of the graft film, the electrical resistance of the graft film is 20 to 120 mΩ · in ² by using the graft polymer having the above-mentioned graft ratio. It can be controlled so as to have a suitable value of. The electrical resistance of the graft film is a value obtained by the AC voltage drop method (1 kHz). If the atmospheric temperature is 20 to 25 ° C, the film is immersed in a 40% KOH (specific gravity: 1.400 ± 0.005) aqueous solution at 25 ± 1 ° C, taken out after 5 to 15 hours, and the electrical resistance is measured. good.

Graft rate (%) = 100 × (AB) / B (2)

In the formula (2), A: the mass (g) of the graft polymer, B: the mass (g) of the stem polymer in the graft polymer. The "B (mass of the stem polymer in the graft polymer)" of the above formula (2) is, for example, graft-polymerizing the graft polymer to the polyolefin which is the stem polymer with (meth) acrylic acid or a derivative thereof. When it is formed by the method, the mass of the stem polymer used for this graft polymerization may be measured in advance. Further, in the graft polymer, the graft ratio may exceed 100% when the monomers used for the graft polymerization [(meth) acrylic acid or its derivative] are polymerized to form a long-chain graft molecule. Because there is. The upper limit of the graft ratio of the graft polymer defined by the above formula (2) is preferably 400%. The above-mentioned "(meth) acrylic acid" is a collective expression of acrylic acid and methacrylic acid.

In the case of a separator composed of only a cellophane film, the thickness thereof is preferably, for example, 15 μm or more, preferably 40 μm or less, and more preferably 30 μm or less.

Further, in the case of a separator composed of a laminate of a graft film and a cellophane film, the total thickness of the graft film and the cellophane film is preferably, for example, 30 μm or more, more preferably 40 μm or more, and further. , 70 μm or less, more preferably 60 μm or less.

Further, in the case of a separator composed of a laminate of a graft film and a cellophane film, the thickness of the graft film is preferably, for example, 15 μm or more, more preferably 25 μm or more, and 30 μm or less. Is preferable.

Examples of the laminate of the graft film and the cellophane film for forming the separator include those commercially available from Yuasa Membrane System Co., Ltd. under the names of "YG9132", "YG9122", and "YG2152".

Further, the separator may be formed by combining a cellophane film, a cellophane film and a graft film with a liquid absorbing layer (electrolyte holding layer) such as vinylon-rayon mixed paper. The thickness of such a liquid absorbing layer is preferably 20 to 500 μm.

As described above, the sheet-shaped air battery of the present invention has a sheet-shaped exterior body. In addition to being able to be applied to applications that are difficult to use in the form with an outer can, it is easier to dispose of than in the form with an outer can, so it can be expected to take advantage of the small environmental load.

The sheet-like exterior body can be made of, for example, a resin film, and examples of such a resin film include a nylon film (nylon 66 film and the like), a polyester film [polyethylene terephthalate (PET) film and the like], and the like. The thickness of the resin film is preferably 20 to 100 μm.

It should be noted that the sealing of the sheet-shaped exterior body is generally performed by heat fusion between the end portion of the resin film on the upper side of the sheet-shaped exterior body and the end portion of the resin film on the lower side. For the purpose of facilitating attachment, a heat-fused resin layer may be laminated on the above-exemplified resin film and used for a sheet-like exterior body. Examples of the heat-sealed resin constituting the heat-sealed resin layer include a modified polyolefin film (modified polyolefin ionomer film and the like), polypropylene and a copolymer thereof. The thickness of the heat-sealed resin layer is preferably 20 to 100 μm.

Further, a metal layer may be laminated on the resin film. The metal layer can be made of an aluminum film (aluminum foil, including an aluminum alloy foil), a stainless steel film (stainless steel foil), or the like. The thickness of the metal layer is preferably 10 to 150 μm.

Further, the resin film constituting the sheet-like exterior body may be a film having a structure in which the heat-sealed resin layer and the metal layer are laminated.

The shape of the sheet-like exterior body may be a polygon (triangle, quadrangle, pentagon, hexagon, heptagon, octagon) in a plan view, or may be a circle or an ellipse in a plan view. In the case of a polygonal sheet-like exterior body in a plan view, the terminal portions of the positive electrode and the negative electrode may be pulled out from the same side to the outside as shown in FIG. 1, or each may be pulled out from a different side to the outside. do not have.

Further, FIG. 5 shows a plan view schematically showing another example of the sheet-shaped air battery. The positive electrode terminal and the negative electrode terminal of the sheet-shaped air battery may be exposed from the sheet-shaped exterior body so that they can be electrically connected to the device to which the battery is applied, as shown in FIG. As shown, a hole may be formed in a part of the sheet-like exterior body 60 (a part of the heat-sealed portion), and the terminal portion 20b of the positive electrode 20 and the terminal portion 30b of the negative electrode 30 may be exposed by the holes. .. When a hole is formed in a part of the sheet-shaped exterior body to expose the terminal portions of the positive electrode and the negative electrode, the sheet-shaped exterior body protects the terminal portions and suppresses damage to each terminal portion. Even if a positive electrode or a negative electrode is formed by using a porous carbon sheet or a metal foil having low strength, it is possible to improve the handleability of the sheet-shaped air battery. Further, a notch may be provided in a part of the sheet-like exterior body instead of the hole, and the terminal portion 20b of the positive electrode 20 and the terminal portion 30b of the negative electrode 30 may be exposed there.

As shown in FIG. 2, the sheet-shaped air battery usually has a water-repellent film arranged between the positive electrode and the exterior body, and the water-repellent film is a film that is water-repellent but allows air to pass through. Is used. Specific examples of such a water-repellent film include a film made of a fluororesin such as PTFE; a polyolefin such as polypropylene and polyethylene; and a resin such as a resin. The thickness of the water-repellent film is preferably 50 to 250 μm.

Further, an air diffusion film for supplying the air taken into the outer body to the positive electrode may be arranged between the outer body and the water repellent film. As the air diffusion film, 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.

The thickness of the sheet-shaped air battery (length a in FIG. 2) is not particularly limited and can be appropriately changed according to the application of the sheet-shaped air battery. One of the advantages of the sheet-shaped air battery is that it can be made thin, and from this viewpoint, the thickness is preferably 1 mm or less, for example.

Further, the lower limit of the thickness of the sheet-shaped air battery is not particularly limited, but it is usually preferably 0.2 mm or more in order to secure a certain capacity.

The sheet-shaped air battery of the present invention can be assembled, for example, as follows. FIG. 6 describes an example of an assembling method of the sheet-shaped air battery, and shows the arrangement (stacking order) of each component of the sheet-shaped air battery.

A porous conductive base material (porous carbon sheet) is punched into the shape shown in FIG. 3 to prepare a positive electrode 20 having a main body portion and a terminal portion. Similarly, a metal foil (zinc alloy foil) is punched into the shape shown in FIG. 4, and a negative electrode 30 having a main body portion and a terminal portion is manufactured. Further, the separator 40 (laminate of graft film and semipermeable membrane) and water repellent film 50 (PTFE film) are punched into a predetermined shape in advance, and the resin film (aluminum laminated film) is also punched into a predetermined shape. Two sheet-shaped exterior bodies are produced.

Of the prepared sheet-shaped exterior bodies, the exterior body 60a (outer body for the positive electrode) arranged on the positive electrode side is formed with air holes 61 at positions corresponding to the main body of the positive electrode 20, and further on the inner surface side thereof. The water-repellent film is heat-welded using a hot melt resin. Further, in the exterior body 60b (exterior body for negative electrode) arranged on the negative electrode side, in order to improve the sealing property of the heat-welded portion of the portion where the terminal portion is arranged, the exterior body 60b is parallel to the side where the terminal portion is located. A hot melt resin 70 (modified polyolefin ionomer film, etc.) is attached.

Next, the positive electrode 20, the separator 40, and the negative electrode 30 are laminated in this order on the water-repellent film 50 of the exterior body 60a arranged on the positive electrode side, and the exterior body 60b arranged on the negative electrode side is further laminated. The hot melt resin 70 is stacked so as to be arranged on the terminal portion, and the three sides around the two exterior bodies are heat-welded to each other to form a bag shape, and after injecting an electrolyte from the opening, the said. The opening is heat-welded and sealed to produce a sheet-shaped air battery.

In the sheet-shaped air battery of the present invention, it is possible to arrange the positive electrodes on both sides of the negative electrode, and in that case, both of the two sheet-shaped exterior bodies face the positive electrode. Therefore, two exterior bodies for the positive electrode will be prepared. Further, by folding back one sheet-shaped exterior body, one side may be used as a positive electrode exterior body and the other side may be used as a negative electrode exterior body.

The sheet-shaped air battery of the present invention is a device for medical / health use, such as a patch that can be attached to the body, particularly a patch that is attached to the surface of the skin to measure physical conditions such as body temperature, pulse, and sweating. It is suitable as a power source for the above, and can also be applied to the same applications in which a conventionally known air battery is adopted.

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>
DBP oil absorption 495 cm 3/100 g, specific surface area 1270 ^{m 2 /} g carbon (Ketchen Black EC600JD (Lion Specialty Chemicals)): 30 parts by mass, acrylic dispersant: 15 parts by mass, SBR: 60 parts by mass And water: 500 parts by mass were mixed to prepare a composition for forming a catalyst-containing layer.

Using porous carbon paper [thickness: 0.25 mm, porosity: 75%, air permeability (garley): 70 seconds / 100 ml] as the porous conductive substrate, the composition for forming the catalyst-containing layer was prepared. A porous conductive substrate having a portion in which a catalyst-containing layer is formed and a portion in which a catalyst-containing layer is not formed by applying stripes to the surface of the substrate so that the coating amount after drying is 10 mg / cm ² and drying. Got This porous conductive substrate is punched into a shape having a main body portion having a size of 15 mm × 15 mm in which a catalyst-containing layer is formed and a terminal portion having a size of 5 mm × 15 mm in which a catalyst-containing layer is not formed. , A positive electrode (air electrode) having an overall thickness of 0.27 mm was produced.

<Negative electrode>
A zinc alloy foil (thickness: 0.05 mm) containing In: 0.05%, Bi: 0.04% and Al: 0.001% as additive elements is provided in a main body having a size of 15 mm × 15 mm and 5 mm ×. A negative electrode having a theoretical capacity of about 65 mAh was produced by punching into a shape having a terminal portion having a size of 15 mm.

<Electrolytic solution>
An aqueous ammonium chloride solution (pH = 4.3) having a concentration of 3.9 mol / l was used as the electrolytic solution.

<Separator>
For the separator, two graft films (thickness per sheet: 15 μm) composed of a graft copolymer having a structure in which acrylic acid is graft-copolymerized on a polyethylene main chain are used, and a cellophane film (thickness: 20 μm) is used. (Overall thickness: 50 μm) arranged on both sides of the above was used.

<Water repellent film>
As the water-repellent film, a porous PTFE sheet having a thickness of 200 μm was used.

<Sheet-like exterior>
Two aluminum laminated films (thickness: 65 μm) having a size of 25 mm × 25 mm having a PET film on the outer surface of the aluminum foil and a polypropylene film as a heat-sealing resin layer on the inner surface were used to form a sheet-like exterior body.

On one exterior body, nine air holes having a diameter of 0.5 mm are regularly formed at equal intervals of 4.5 mm in length × 4.5 mm in width (the distance between the centers of the air holes is 5 mm), and further. The water-repellent film was heat-welded to the inner surface side using a hot melt resin. Further, on the other exterior body, a modified polyolefin ionomer film was attached in parallel with the sides of the exterior body at the portion where the terminal portions of the positive electrode and the negative electrode were arranged.

<Battery assembly>
The positive electrode, the separator, and the negative electrode are laminated in this order on the water-repellent film of the exterior body with the sheet-like exterior body having the water-repellent film facing down, and another exterior body is further attached. The modified polyolefin ionomer film was laminated so as to be located on the terminals of the positive electrode and the negative electrode. Next, the three sides around the two exterior bodies are heat-welded to each other to form a bag, and then 0.1 ml of the electrolytic solution is injected through the opening, and then the opening is heat-welded and sealed. A sheet-shaped air battery was manufactured.

(Comparative Example 1)
<Positive electrode>
The carbon: 75 parts by mass, PTFE: 25 parts by mass, and water used in Example 1 were mixed and rolled to prepare a sheet for forming a catalyst-containing layer. Next, this sheet was pressure-bonded to a current collector made of SUS304 and made of a 700 mesh metal mesh (wire diameter: 0.1 mm, thickness: 0.25 mm) and then dried, and the size of the catalyst-containing layer was 15 mm. It became × 15 mm and was punched into a shape having an exposed part of the current collector at one end. Further, a nickel lead wire having a size of 5 mm × 15 mm was welded to the exposed portion of the current collector to form a terminal portion, and a positive electrode (air electrode) having an overall thickness of 0.3 mm was produced.

<Negative electrode>
Zinc alloy particles containing In: 500 ppm, Bi: 400 ppm and Al: 10 ppm as additive elements were dispersed in an aqueous solution of carboxymethyl cellulose to prepare a paste for a negative electrode. Next, the paste is filled in the pores of a nickel foam base material (current collector) having one end compressed to form a conductive tab, dried, lightly pressed, and then filled with the paste. (Negative electrode mixture layer) was cut so as to have a size of 15 mm × 15 mm. Further, a nickel lead wire having a size of 5 mm × 15 mm was welded to the conductive tab to form a terminal portion, and a negative electrode having a theoretical capacity of about 65 mAh containing 80 mg of the zinc alloy particles was prepared.

<Battery assembly>
A sheet-shaped air battery was produced in the same manner as in Example 1 except that the positive electrode and the negative electrode were used.

The sheet-shaped air batteries of Example 1 and Comparative Example 1 were left in the air for 10 minutes after assembly, and then the opening voltage of the batteries was measured. Further, a discharge resistance of 3.9 kΩ was connected, and the discharge capacity until the battery voltage dropped to 0.5 V was measured. The measurement results are shown in Table 1.

The sheet-shaped air battery of the present invention, which can be manufactured by a simpler method than the conventional sheet-shaped air battery, is excellent in productivity, while, as shown in Table 1, the conventional sheet-shaped air battery is used. As with the battery, excellent characteristics can be obtained.

1 Sheet-shaped air battery 20 Positive electrode (air electrode)
20a Positive electrode body 20b Positive electrode terminal 30 Negative electrode 30a Negative electrode body 30b Negative electrode terminal 40 Separator 50 Water repellent film 60 Sheet-like exterior body 61 Air hole 70 Hot melt resin

Claims (8)

A sheet-shaped air battery in which a positive electrode, a negative electrode, a separator, and an electrolyte are housed in a sheet-shaped exterior.
The positive electrode has a porous conductive substrate and has a porous conductive substrate.
The porous conductive substrate has a main body portion and a terminal portion that function as a current collector for the positive electrode, and the terminal portion has at least a part exposed to the outside of the sheet-like exterior body.
The negative electrode has a metal foil and
The metal foil has a main body portion and a terminal portion that function as an active material of the negative electrode, and the terminal portion has at least a part exposed to the outside of the sheet-like exterior body .
A sheet-shaped air battery characterized in that the entire surface of the main body of the negative electrode on the positive electrode side faces the separator . The sheet-shaped air battery according to claim 1, wherein the porous conductive base material is a porous carbon sheet made of fibrous carbon. The sheet-shaped air battery according to claim 1 or 2, wherein a carbon catalyst is supported on the surface or inside of a porous conductive base material constituting the main body of the positive electrode. A hole or a notch is formed in the sheet-like exterior body, and the sheet-like exterior body has a hole or a notch.
The sheet-shaped air battery according to any one of claims 1 to 3, wherein the positive electrode and the terminal portion of the negative electrode are exposed from the hole or the notch. The sheet-shaped air battery according to any one of claims 1 to 4, wherein the metal foil is a zinc or a zinc alloy foil, a magnesium or a magnesium alloy foil, or an aluminum or an aluminum alloy foil. The sheet-shaped air battery according to any one of claims 1 to 5, wherein the electrolyte is an aqueous solution containing an electrolyte salt and having a pH of 3 or more and less than 12. The sheet-shaped air battery according to claim 6, wherein the aqueous solution constituting the electrolyte is gelled. A patch that can be attached to a body and is characterized by having a sheet-shaped air battery according to any one of claims 1 to 7 as a power source.

Images