JP2020030925A - Alkaline battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an alkaline battery having good discharge characteristics.
SOLUTION: The alkaline battery of the present invention has a positive electrode, a negative electrode, and an alkaline electrolyte. The positive electrode contains a positive electrode material obtained by mechanically fixing carbon particles on the surface of silver oxide particles. Characterized by having an agent layer. The carbon particles of the positive electrode material are preferably carbon black particles.
[Selection diagram] Fig. 2

Description

  The present invention relates to an alkaline battery having good discharge characteristics.

  Alkaline batteries (silver oxide batteries) having a positive electrode containing silver oxide and an alkaline electrolyte have been widely and generally used as primary batteries because of their large discharge capacity and excellent flatness of discharge voltage.

On the other hand, utilization of an alkaline battery using a silver oxide for a positive electrode as a secondary battery is also being studied. The reaction of the positive electrode at the time of charging in this battery is considered to be the reaction of the following formula (1) or formula (2).
_{^{2Ag + 2OH - → Ag 2 O}} + H 2 O + 2e - (1)
^{_{Ag 2 O + 2OH - → 2AgO}} + H 2 O + 2e - (2)

  Also, in such alkaline batteries, various improvements in characteristics have been attempted. For example, Patent Document 1 discloses that by coating silver (I) oxide particles serving as a positive electrode active material with a fine carbon material, the conductivity in the positive electrode mixture is increased, the charge / discharge efficiency is high, and the cycle life is improved. It has been shown that long silver oxide batteries can be constructed.

  Patent Document 1 discloses that in order to prolong the cycle life of a battery, it is necessary to increase the amount of a carbon material covering silver (I) oxide particles to some extent. Therefore, according to the technology described in Patent Literature 1, while the specific characteristics of the silver oxide battery are improved, characteristics (for example, discharge capacity) that are impaired by increasing the amount of the carbon material in the positive electrode mixture are also increased. is there. The technique described in Patent Document 1 has room for improvement in such a point.

Japanese Patent Application Laid-Open No. 2001-202958 (Claims, Examples)

  The present invention has been made in view of the above circumstances, and an object of the present invention is to provide an alkaline battery having good discharge characteristics.

  The alkaline battery of the present invention has a positive electrode, a negative electrode and an alkaline electrolyte, and the positive electrode has a positive electrode mixture layer containing a positive electrode material obtained by mechanically fixing carbon particles on the surface of silver oxide particles. It is characterized by the following.

  According to the present invention, an alkaline battery having good discharge characteristics can be provided.

It is a side view showing typically an example of the alkaline battery of the present invention. It is principal part sectional drawing of the alkaline battery shown in FIG. 4 is a graph showing the evaluation results of the charge and discharge cycle characteristics of the alkaline batteries of Examples 1 and 2 and Comparative Examples 1 and 2. 4 is a discharge curve of the alkaline batteries of Example 1 and Comparative Example 1. 9 is a graph showing load characteristics of the alkaline batteries of Example 3 and Comparative Example 3.

  The alkaline battery of the present invention has a positive electrode, a negative electrode, and an alkaline electrolyte, and the positive electrode has a positive electrode mixture layer containing a positive electrode material in which carbon particles are mechanically fixed to the surface of silver oxide particles. ing.

  As described in Patent Document 1, when a positive electrode material in which the surface of silver oxide particles is coated with a fine carbon material is used, sufficient characteristics (for example, charge-discharge cycle characteristics) can be ensured. It is necessary to relatively increase the amount of carbon material required for coating. In Patent Document 1, when coating the surface of silver oxide particles with a carbon material, a basic solution is added to a silver salt aqueous solution containing carbon particles to precipitate silver oxide particles, and the surroundings are coated with carbon particles. Although the coating method is shown, as pointed out in Patent Document 1, the carbon particles dispersed in the silver salt aqueous solution are not only deposited on the surface but also inside the silver oxide particles when the silver oxide particles are precipitated. As a result, the proportion of the carbon material (carbon particles) present on the surface of the silver oxide particles that can contribute to the improvement of the conductivity among the carbon materials (carbon particles) in the obtained material is reduced. It can be one of the factors that increase the volume.

  Therefore, in the present invention, a positive electrode material in which the surface of silver oxide particles serving as a positive electrode active material of an alkaline battery is mechanically fixed rather than simply coated with a carbon material is used. This makes it possible to increase the utilization rate of silver oxide, which is a positive electrode active material, in an alkaline battery while reducing the amount of carbon material adhered to silver oxide particles. Therefore, when the alkaline battery of the present invention is a primary battery, the discharge capacity and load characteristics can be increased and the impedance can be reduced. When the alkaline battery of the present invention is a secondary battery, the charge / discharge efficiency and the charge / discharge cycle characteristics can be improved, and the impedance can be reduced.

  The positive electrode according to the alkaline battery has a positive electrode mixture layer containing a positive electrode material obtained by mechanically fixing carbon particles on the surface of silver oxide particles. In the alkaline battery, silver oxide constituting silver oxide particles in the positive electrode material functions as a positive electrode active material. The positive electrode may be composed only of the positive electrode mixture layer (molded product of the positive electrode mixture) or may have a structure in which the positive electrode mixture layer is formed on the current collector.

  In the silver oxide particles constituting the positive electrode material used in the positive electrode of the alkaline battery, not only are the carbon particles adhered to the surface, but also some of the silver particles are buried from the surface of the silver oxide particles to the inside. It is considered that the carbon particles are pressed against the oxide particles, which probably makes it difficult for the carbon particles to be detached from the surface of the silver oxide particles. Therefore, the fact that the carbon particles existing on the surface of the silver oxide particles are mechanically fixed means that the silver oxide particles are mechanically stimulated (for example, after being stirred by a ball mill). It can be confirmed that the carbon particles remain on the surface of the material particles. The remaining carbon particles on the surfaces of the silver oxide particles may be confirmed by observation with a scanning electron microscope photograph or the like.

The silver oxide constituting the silver oxide particles include AgO or Ag 2 _O.

  When an alkaline battery is used as a secondary battery, Bi is preferably contained in the silver oxide constituting the silver oxide particles. In an alkaline battery using silver oxide as the positive electrode active material, a phenomenon in which the voltage suddenly drops when the capacity is reduced by discharging (the stage where the capacity is still left) is likely to occur. This phenomenon has an adverse effect on the charge / discharge cycle characteristics. However, in an alkaline secondary battery using a Bi-containing silver oxide as a positive electrode active material, the above-described voltage drop is suppressed, so that the charge / discharge cycle characteristics can be improved. On the other hand, when the alkaline battery is a primary battery, the silver oxide does not need to contain Bi, but may contain Bi.

  When Bi is contained in the silver oxide, the content is preferably 1 to 10% by mass as a ratio of the total amount of Bi to the total amount of silver.

  The particle size of the silver oxide particles is not particularly limited, but the average particle size is preferably 10 μm or less, more preferably 2 μm or less. When a silver oxide having such a size is used, the charge utilization rate is improved, and a large charge capacity can be obtained even when the charge end voltage is relatively low, so that the charge / discharge cycle characteristics of the battery are further improved. For example, it is possible to suppress the swelling of the battery that can be caused by increasing the charge end voltage.

  However, the average particle diameter of the silver oxide is preferably 0.01 μm or more, and more preferably 0.03 μm or more, since the production and subsequent handling of the silver oxide having a very small particle diameter becomes difficult. More preferred.

The average particle diameter of the silver oxide particles and other particles (carbon particles such as carbon black particles and graphite particles described below, and insulating inorganic particles) referred to in the present specification is measured using a laser scattering particle size distribution meter (for example, manufactured by Horiba, Ltd.). using "LA-920"), a medium which does not dissolve the particles, the particles were measured by dispersing a particle size (D ₅₀₎ in the cumulative frequency of 50% by volume.

  Examples of carbon particles mechanically fixed to the surface of silver oxide particles include carbon black particles such as furnace black, channel black, acetylene black, and thermal black; particles of natural graphite (eg, flaky graphite), and particles of artificial graphite. Graphite particles; and the like. As the carbon particles, only one of the above-described examples may be used, or two or more of the carbon particles may be used in combination. It is more preferable to use carbon black particles because they are easily available.

  The average particle diameter of the carbon particles fixed to the surface of the silver oxide particles is preferably 0.1 μm or less from the viewpoint that the particles are easily fixed on average, and 0.01 μm or more from the viewpoint of good handleability. It is preferred that

  As a method of mechanically fixing the carbon particles on the surface of the silver oxide particles, a method of repeatedly applying a large impact force such as a compressive force, a frictional force, or a shearing force to a mixture of both can be used. Specifically, a hybridizing system (manufactured by Nara Machinery Co., Ltd.) that combines particles with each other in a dry manner using a force mainly consisting of impact force while dispersing the raw material in a high-speed air stream, or a rotor with a special shape By using a device such as Novirta (made by Hosokawa Micron) that rotates and applies impact, compression, and shear forces to individual particles to combine the particles, the fine particles on the surface of the core particles (silver oxide particles) (Carbon particles) can be immobilized.

  The content of the carbon particles in the positive electrode material is preferably 0.1% by mass or more, from the viewpoint of increasing the conductivity of the silver oxide by increasing the conductivity in the positive electrode material mixture layer. More preferably, it is at least 5% by mass. However, if the amount of the carbon material in the positive electrode material is too large, for example, the amount of silver oxide particles in the positive electrode material may decrease, and the capacity of the battery may decrease. Therefore, from the viewpoint of further increasing the capacity of the battery, the content of the carbon particles in the positive electrode material is preferably 3% by mass or less, and more preferably 2% by mass or less.

  In the positive electrode material, the carbon particles mechanically fixed to the surface of the silver oxide particles function as a conductive auxiliary in the positive electrode mixture layer, but the positive electrode mixture layer is different from the carbon particles (ie, (Which is not mechanically fixed to the surface of the silver oxide particles).

  Examples of such a conductive aid include carbon black particles and graphite particles exemplified above as specific examples of the carbon material to be mechanically fixed to the surface of silver oxide particles. More than one species can be used.

  It is more preferable to use graphite particles as the conductive additive, whereby the moldability of the positive electrode mixture layer is improved. Depending on the thickness of the positive electrode mixture layer, it is necessary to use a binder to enhance the formability, but when graphite particles are used as the conductive aid, the function of enhancing the formability of the positive electrode mixture layer Thereby, for example, even when the molded product of the positive electrode mixture or the positive electrode mixture layer is as thin as 0.4 mm or less, more preferably 0.3 mm or less, the moldability is improved, and the production failure occurs without using a binder. Can be easily prevented.

  When graphite particles are used as the conductive additive, the average particle size is preferably 1 μm or more, and more preferably 2 μm or more, since the function of enhancing the moldability of the positive electrode mixture layer is further improved. From the viewpoint of improving conductivity, the thickness is more preferably 7 μm or less, and more preferably 5 μm or less.

  Further, the positive electrode mixture layer may contain insulating inorganic particles. In particular, when the alkaline battery is a secondary battery, the charge-discharge cycle characteristics can be enhanced by including the insulating inorganic particles in the positive electrode mixture layer.

Examples of the insulating inorganic particles include particles such as oxides of at least one element selected from Si, Zr, Ti, Al, Mg, and Ca. Specific examples of the oxide include Al ₂ O ₃ , TiO ₂ , SiO ₂ , ZrO ₂ , MgO, CaO, AlOOH, and Al (OH) _3. Are preferably used. When the positive electrode mixture layer contains insulating inorganic particles, one or more of the above-mentioned examples may be used.

  If the particle diameter of the insulating inorganic particles is too large, the effect of improving the charge / discharge cycle characteristics of the battery may be reduced. Therefore, from the viewpoint of further improving the charge / discharge cycle characteristics of the battery, the average particle diameter of the insulating inorganic particles is preferably 0.5 μm or less, more preferably 0.3 μm or less.

  If the particle diameter of the insulating inorganic particles is too small, the effect of improving the charging efficiency (initial capacity) of the battery may be reduced. Therefore, from the viewpoint of better enhancing the charging efficiency of the battery, the average particle size of the insulating inorganic particles is preferably 0.01 μm or more, and more preferably 0.05 μm or more.

  As for the composition of the positive electrode mixture layer (eg, the positive electrode mixture molded article and the positive electrode mixture coating layer formed on the current collector), carbon particles were mechanically fixed to the surface to secure the capacity. The content of the silver oxide particles (the amount including the carbon particles present on the surface) is preferably, for example, 60% by mass or more, assuming that the entire solid content of the positive electrode mixture layer is 100% by mass, It is more preferably at least 80% by mass, particularly preferably at least 90% by mass.

  When graphite particles are used as the conductive additive, the content of the graphite particles in the positive electrode mixture layer is 1% by mass from the viewpoint of satisfactorily improving the moldability and conductivity of the positive electrode mixture layer. It is more preferably at least 2% by mass. The content of the graphite particles in the positive electrode mixture layer is preferably 7% by mass or less, for example, from the viewpoint of preventing the amount of silver oxide in the positive electrode mixture layer from becoming too small and reducing the capacity of the battery. , And more preferably 4% by mass or less.

  When carbon black particles are used as the conductive additive, the content of the carbon black particles in the positive electrode mixture layer is 0.1% by mass from the viewpoint of ensuring the effect of improving the conductivity of the positive electrode mixture layer. It is preferably at least 0.5 mass%, more preferably at least 0.5 mass%. However, if the amount of the carbon black particles in the positive electrode mixture layer is too large, for example, when the battery is stored at a high temperature, the swelling amount of the positive electrode may increase. Therefore, from the viewpoint of suppressing the swelling of the positive electrode during storage of the battery (particularly storage at a high temperature of about 60 ° C.) and improving the storage characteristics of the battery, the content of the carbon black particles in the positive electrode mixture layer is: It is preferably at most 1.5 mass%, more preferably at most 1 mass%.

  In addition, the content of the insulating inorganic particles in the positive electrode mixture layer is preferably 0.1% by mass or more from the viewpoint of ensuring the effect of the use thereof (particularly, the effect of improving the charge and discharge cycle characteristics of the battery). And more preferably 3% by mass or more. However, if the amount of the insulating inorganic particles in the positive electrode mixture layer is too large, the filling amount of the positive electrode active material is reduced and the capacity of the battery is reduced, and depending on the type of the insulating inorganic particles, the charge / discharge cycle is reduced. Since the discharge capacity may suddenly decrease when the process proceeds, the content of the insulating inorganic particles in the positive electrode mixture layer is preferably 7% by mass or less, and more preferably 5% by mass or less. Is more preferable.

  As described above, the positive electrode mixture layer can be formed without using a binder. However, when it is necessary to increase the strength (for example, when graphite particles are not used as a conductive additive), a binder is used. You may. Examples of the binder of the positive electrode mixture layer include a fluororesin such as polytetrafluoroethylene. When a binder is used, the content of the binder in the positive electrode mixture layer is preferably 0.1 to 20% by mass.

  When the positive electrode is a molded product of a positive electrode mixture, for example, a positive electrode active material and a conductive auxiliary agent, and further, if necessary, an alkaline electrolyte (the same one as the alkaline electrolyte to be injected into the battery can be used). The positive electrode mixture prepared by mixing can be manufactured by pressure molding into a predetermined shape.

  In the case of a positive electrode having a positive electrode mixture layer and a current collector, for example, a positive electrode active material and a conductive auxiliary are dispersed in water or an organic solvent such as N-methyl-2-pyrrolidone (NMP). Thus, a positive electrode mixture-containing composition (slurry, paste, or the like) is prepared, applied to a current collector, dried, and optionally subjected to a pressing process such as a calendaring process. .

  However, the positive electrode is not limited to those manufactured by the above methods, and may be manufactured by another method.

  When the molded product of the positive electrode mixture is used as the positive electrode, the thickness is preferably 0.15 to 4 mm. On the other hand, in the case of a positive electrode having a positive electrode mixture layer and a current collector, the thickness of the positive electrode mixture layer (the thickness per one side of the current collector) is preferably 30 to 300 μm.

  When a current collector is used for the positive electrode, the current collector may be, for example, one made of stainless steel such as SUS316, SUS430, or SUS444; nickel or a nickel alloy; Examples thereof include a wire net, an expanded metal, a lath net, a punched metal, a metal foam, and a foil (plate). The thickness of the current collector is preferably, for example, 0.05 to 0.2 mm. It is also desirable to apply a paste-like conductive material such as a carbon paste or a silver paste on the surface of such a current collector.

  As the negative electrode of the alkaline battery, a negative electrode containing zinc particles or zinc alloy particles (hereinafter, both may be collectively referred to as “zinc-based particles”) is used. In such a negative electrode, zinc in the particles acts as an active material. Examples of the alloy component of the zinc alloy particles include indium (for example, the content is 50 to 500 ppm on a mass basis), bismuth (for example, the content is 50 to 500 ppm on a mass basis), and the like (the remainder is zinc and unavoidable impurities). is there). The zinc-based particles of the negative electrode may be used alone or in combination of two or more.

  However, it is preferable to use a zinc-based particle that does not contain mercury as an alloy component. With a battery using such zinc-based particles, environmental pollution due to battery disposal can be suppressed. For the same reason as in the case of mercury, it is preferable to use zinc-based particles that do not contain lead as an alloy component.

  As the particle size of the zinc-based particles, for example, the ratio of particles having a particle size of 75 μm or less is preferably 50% by mass or less, more preferably 30% by mass or less, and the particle size is 100 to 100%. A powder in which the proportion of a 200 μm powder is 50% by mass or more, more preferably 90% by mass or more. Here, the particle size of the zinc-based particles is a value obtained by the same measuring method as the above-described method for measuring the average particle size of silver oxide.

  The negative electrode may contain, for example, a gelling agent (such as sodium polyacrylate or carboxymethylcellulose) that is added as necessary, in addition to the zinc-based particles, and may be formed by adding an alkaline electrolyte. The negative electrode agent (gelled negative electrode) used may be used. The amount of the gelling agent in the negative electrode is preferably, for example, 0.5 to 1.5% by mass.

  In addition, the negative electrode may be a non-gelled negative electrode substantially not containing a gelling agent as described above (in the case of a non-gelled negative electrode, the amount of the alkaline electrolyte present near the zinc-based particles increases. If it does not stick, it may contain a gelling agent, so that "substantially contains no gelling agent" means that it may be contained to the extent that it does not affect the viscosity of the alkaline electrolyte. Meaning). In the case of a gelled negative electrode, an alkaline electrolyte is present together with a gelling agent in the vicinity of the zinc-based particles, but the alkali electrolyte is thickened by the action of the gelling agent. The movement and, consequently, the movement of ions in the electrolytic solution are suppressed. For this reason, it is considered that the reaction speed at the negative electrode was suppressed, which hindered the improvement of the load characteristics (particularly heavy load characteristics) of the battery. On the other hand, the reaction rate at the anode is increased by keeping the movement rate of ions in the alkaline electrolyte high without increasing the viscosity of the alkaline electrolyte existing near the zinc-based particles by making the anode non-gelled. Thus, load characteristics (particularly heavy load characteristics) can be further improved.

  The same alkaline electrolyte to be injected into the battery can be used as the alkaline electrolyte contained in the negative electrode.

  The content of the zinc-based particles in the negative electrode is, for example, preferably 60% by mass or more, more preferably 65% by mass or more, and preferably 75% by mass or less, and more preferably 70% by mass or less. More preferably, there is.

  The negative electrode preferably contains an indium compound. When the negative electrode contains the indium compound, gas generation due to a corrosion reaction between the zinc-based particles and the alkaline electrolyte can be more effectively prevented.

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

  The amount of the indium compound used in the negative electrode is preferably 0.003 to 1 with respect to zinc-based particles: 100 by mass ratio.

  As the alkaline electrolyte used for the alkaline battery, one or more aqueous solutions of alkali metal hydroxides (such as sodium hydroxide, potassium hydroxide, and lithium hydroxide) are preferably used. Potassium is particularly preferred. As for the concentration of the alkaline electrolyte, for example, in the case of an aqueous solution of potassium hydroxide, potassium hydroxide is preferably at least 20% by mass, more preferably at least 30% by mass, and preferably at most 40% by mass, more preferably 38% by mass or less. By adjusting the concentration of the aqueous solution of potassium hydroxide to such a value, an alkaline electrolyte having excellent conductivity can be obtained.

  In addition to the above-described components, various known additives may be added to the alkaline electrolyte, as long as the effects of the present invention are not impaired. For example, zinc oxide may be added to prevent corrosion (oxidation) of the zinc-based particles used for the negative electrode of the alkaline battery. Note that zinc oxide can be added to the negative electrode.

  Further, it is preferable that at least one selected from the group consisting of a manganese compound, a tin compound and an indium compound is dissolved in the alkaline electrolyte. When these compounds are dissolved in the alkaline electrolyte, ions (manganese ions, tin ions, and indium ions) derived from these compounds are eluted when manganese oxide is contained in the positive electrode mixture layer. Since the same effect as that of Mn ions is obtained, the charge / discharge cycle characteristics of the battery are further improved.

  Manganese compounds to be dissolved in the alkaline electrolyte include manganese chloride, manganese acetate, manganese sulfide, manganese sulfate, manganese hydroxide and the like. Examples of the tin compound dissolved in the alkaline electrolyte include tin chloride, tin acetate, tin sulfide, tin bromide, tin oxide, tin hydroxide, and tin sulfate. Further, examples of the indium compound to be dissolved in the alkaline electrolyte include indium hydroxide, indium oxide, indium sulfate, indium sulfide, indium nitrate, indium bromide, and indium chloride.

  The concentration of the indium compound, manganese compound and tin compound in the alkaline electrolyte (when only one of these is dissolved, the concentration is used; when two or more are dissolved, the total concentration is used) Is preferably 50 ppm or more, more preferably 500 ppm or more, more preferably 10000 ppm or less, and preferably 5000 ppm or less, on a mass basis, from the viewpoint of better securing the above-mentioned effects. Is more preferred.

  In an alkaline battery, a separator is interposed between a positive electrode and a negative electrode. Examples of separators that can be used in alkaline batteries include non-woven fabrics mainly composed of vinylon and rayon, vinylon-rayon non-woven fabric (vinylon-rayon mixed paper), polyamide non-woven fabric, polyolefin-rayon non-woven fabric, vinylon paper, vinylon linter pulp paper, vinylon. Mercerized pulp paper or the like can be used. Further, a hydrophilically treated microporous polyolefin film (microporous polyethylene film, microporous polypropylene film, etc.), a cellophane film, and an absorbent layer (electrolyte retaining layer) such as vinylon-rayon mixed paper were stacked. The thing may be used as a separator. The thickness of the separator is preferably 20 to 500 μm.

  When the alkaline battery is a secondary battery, a polymer is used as a matrix between the positive electrode and the negative electrode, and metal oxides, hydroxides, carbonates, sulfates, phosphates, borates and the like are contained in the matrix. It is preferable to dispose an anion-conductive membrane in which particles of at least one metal compound selected from the group consisting of acid salts and silicates are dispersed.

  Further, in the alkaline battery, it is preferable that at least one of the negative electrode, the alkaline electrolyte and the separator contains a polyalkylene glycol or a calcium compound. In this case, the growth of zinc dendrite at the negative electrode can be suppressed by the action of the polyalkylene glycols and the calcium compound, so that the charge / discharge cycle characteristics (in the case of a secondary battery) and the storage characteristics of the alkaline battery can be further improved. it can.

  The polyalkylene glycols are compounds having a structure in which an alkylene glycol such as ethylene glycol, propylene glycol or butylene glycol has been polymerized or copolymerized, and may have a crosslinked structure or a branched structure, and may have a terminal. The compound may have a substituted structure, and a compound having a weight average molecular weight of about 200 or more is preferably used. The upper limit of the weight average molecular weight is not particularly limited, but it is preferable that the compound is water-soluble in order to more easily exert the effect of the addition, and usually the compound is preferably 20,000 or less, and preferably 5,000 or less. More preferably used.

  More specifically, polyethylene glycols having a structure in which ethylene glycol is polymerized (polyethylene glycol, polyethylene oxide, etc.) and polypropylene glycols having a structure in which propylene glycol is polymerized (polypropylene glycol, polypropylene oxide, etc.) are preferably used. In addition, a copolymer compound containing an ethylene oxide unit and a propylene oxide unit (eg, polyoxyethylene polyoxypropylene glycol) may be used.

  When polyalkylene glycols are used, the amount is preferably 0.01 to 1.5 parts by mass based on 100 parts by mass of the zinc-based particles.

Further, the calcium compound reacts with Zn (OH) ₄ ²⁻ generated at the time of electric discharge, such as calcium hydroxide, calcium oxide, calcium chloride, calcium sulfate, etc., to form a complex compound such as CaZn (OH) _4. Compounds and the composite compound itself can be exemplified, and calcium hydroxide and calcium oxide can be preferably used.

  When a calcium compound is used, the amount is preferably 5 to 40 parts by mass based on 100 parts by mass of the zinc-based particles.

  The form of the alkaline battery is not particularly limited, and is a flat type (coin type) having a battery case in which an outer can and a sealing plate are swaged and sealed via a gasket, or the outer can and the sealing plate are welded and sealed. , Including a button shape); a laminate type having an exterior body made of a metal laminate film; a bottomed cylindrical exterior can and a sealing plate are caulked through a gasket, or the exterior can and the sealing plate are welded. Any form, such as a cylindrical shape (cylindrical shape, square shape (square tube shape)) having a battery case to be sealed or the like, can be used.

  In addition, when using an exterior body that performs crimping sealing, the gasket material interposed between the exterior can and the sealing plate can be made of polypropylene, nylon, etc. Is required, a fluororesin such as tetrafluoroethylene-perfluoroalkoxyethylene copolymer (PFA), polyphenylene ether (PEE), polysulfone (PSF), polyarylate (PAR), polyethersulfone (PES) ), Polyphenylene sulfide (PPS), polyetheretherketone (PEEK), or other heat-resistant resin having a melting point of more than 240 ° C. can be used. When the battery is used for applications requiring heat resistance, a glass hermetic seal can be used for sealing the battery.

  Further, in order to prevent elution of elements such as iron constituting the outer can at the time of charging, it is desirable that the inner surface of the outer can be plated with a corrosion-resistant metal such as gold.

  The alkaline battery of the present invention can be applied to applications in which conventionally known alkaline primary batteries (such as silver oxide primary batteries), alkaline secondary batteries, and nonaqueous electrolyte secondary batteries are employed.

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

Example 1
<Preparation of positive electrode>
Average particle diameter: 1.4 μm, silver oxide (Ag ₂ O) particles containing 3.7% (by mass) of Bi with respect to the total amount of silver and carbon black particles (BET specific surface area is 68 m ² / g, (Acetylene black having an average primary particle diameter of 35 nm) and a mass ratio of 98: 2 were introduced into “Hybridization System NHS-1 (trade name)” manufactured by Nara Machine Co., Ltd., and the rotation speed of the rotor was 8300 rpm and the rotation speed was 8300 rpm. The particles were treated at a speed of 100 m / s and a treatment time of 3 minutes to prepare a positive electrode material in which acetylene black (AB) particles were mechanically fixed to the surfaces of silver oxide particles. In the positive electrode material, the fact that the AB particles are fixed on the surface of the silver oxide particles is confirmed by stirring the obtained positive electrode material using a ball mill and observing the state before and after the stirring with a scanning electron microscope. (The same applies to the positive electrode material in each example described later).

The positive electrode material and graphite particles (BET specific surface area is 20 m ² / g, average particle diameter is 3.7 μm) and TiO ₂ particles (insulating inorganic particles, average particle diameter: 250 nm) are each 95.2 mass%, 3 The positive electrode mixture was composed by mixing at a ratio of 0.8% by mass and 1% by mass, and 300 mg of the positive electrode mixture was filled in a mold. The packing density was 5.7 g / cm ³ , and the diameter was 10.7 mm. A positive electrode mixture molded body (positive electrode mixture layer) was produced by pressure molding into a disc having a height of 0.6 mm.

  PTFE aqueous dispersion (solid content: 60% by mass): 5 g, aqueous solution of sodium polyacrylate (concentration: 2% by mass): 2.5 g, and hydrotalcite particles (average particle size: 0.4 μm): 2.5 g were kneaded and rolled to produce a film having a thickness of 100 μm, and a punched circular film having a diameter of 11.3 mm was used as an anion-conductive film in assembling a battery.

As the negative electrode active material, mercury-free zinc alloy particles commonly used in alkaline primary batteries and containing 500 ppm, Bi: 400 ppm, and Al: 10 ppm as additive elements were used. As for the particle size of the zinc alloy particles obtained by the method described above, the average particle size (D ₅₀ ) was 120 μm, and the ratio of particles having a particle size of 75 μm or less was 25% by mass or less.

  The zinc alloy particles and ZnO were mixed at a ratio (mass ratio) of 97: 3 to obtain a composition for forming a negative electrode (a negative electrode composition). This composition: 78 mg was weighed and used for the preparation of a negative electrode.

  As the alkaline electrolyte, an aqueous potassium hydroxide solution (concentration of potassium hydroxide: 35% by mass) in which zinc oxide was dissolved at a concentration of 3% by mass was used.

  On the separator, two graft films (thickness: 30 μm) composed of a graft copolymer having a structure in which acrylic acid is graft-copolymerized on a polyethylene main chain are arranged on both sides of a cellophane film (thickness: 20 μm). Further, a laminate of vinylon-rayon mixed paper (thickness: 100 μm) was punched into a circle having a diameter of 11.3 mm and used.

  An outer can made of a steel plate in which the above-described positive electrode (positive electrode mixture molded product), negative electrode (composition for negative electrode), alkaline electrolyte, anion conductive film and separator are plated with gold; )-Sealed in a battery container composed of a sealing plate made of a nickel clad plate and an annular gasket made of nylon 66, having the appearance shown in FIG. 1 and the structure shown in FIG. 2, having a diameter of 11 mm, An alkaline secondary battery having a thickness of 3 mm was produced. The anion conductive membrane was arranged so as to face the negative electrode, and the separator was arranged on the positive electrode side.

In the alkaline secondary battery 1 shown in FIGS. 1 and 2, a sealing plate 3 containing a negative electrode 5 in an opening of an outer can 2 containing a positive electrode 4, a separator 6 and an anion-conductive film 7 has a cross section L The gasket (resin gasket) 8 is fitted through a U-shaped annular gasket, and the open end of the outer can 2 is tightened inward, whereby the resin gasket 8 comes into contact with the sealing plate 3. The opening of the outer can 2 is sealed, and the inside of the battery has a sealed structure. That is, in the battery shown in FIGS. 1 and 2, the positive electrode 4, the negative electrode 5, the separator 6, and the anion conductive membrane are provided in a space (closed space) in a battery container including the outer can 2, the sealing plate 3, and the resin gasket 8. A power generation element including the fuel cell 7 is loaded, and an alkaline electrolyte (not shown) is further injected and held by a separator. The outer can 2 also functions as a positive electrode terminal, and the sealing plate 3 also functions as a negative electrode terminal. As described above, the positive electrode 4 is a molded product of a positive electrode mixture containing the positive electrode material, graphite particles, and TiO ₂ particles.

Example 2
A positive electrode material was prepared in the same manner as in Example 1 except that the ratio (mass ratio) of Bi-containing silver oxide to AB was changed to 99.4: 0.6. An alkaline secondary battery was manufactured in the same manner as in Example 1.

Comparative Example 1
Average particle diameter: 1.4 μm, silver oxide (Ag ₂ O) particles containing 3.7% (by mass) of Bi with respect to the total amount of silver and carbon black particles (BET specific surface area is 68 m ² / g, (Acetylene black having an average primary particle diameter of 35 nm) was mixed at a mass ratio of 98: 2 using a ball mill to prepare a mixture of silver oxide particles and AB particles. Then, an alkaline secondary battery was manufactured in the same manner as in Example 1, except that this mixture was used instead of the positive electrode material.

Comparative Example 2
The same procedure as in Comparative Example 1 was carried out except that the TiO ₂ particles were not contained and the ratios of the silver oxide particles and the carbon black particles were changed to 95.6% by mass and 0.6% by mass, respectively, to constitute the positive electrode mixture. To produce an alkaline secondary battery.

  The following evaluations were performed on the alkaline secondary batteries of Examples 1 and 2 and Comparative Examples 1 and 2.

[Evaluation of discharge characteristics, charge / discharge efficiency and charge / discharge cycle characteristics]
Each of the alkaline secondary batteries was discharged at a constant current of 4 mA until the voltage reached 1.0 V, charged at a constant current of 8 mA until the voltage reached 1.8 V, and then charged at a constant current of 1.8 V. One cycle was defined as constant current-constant voltage charging in which the voltage was charged until the current value reached 0.8 mA. These cycles were repeated for 10 cycles, and the discharge capacity and charge capacity during each cycle were measured.

  Further, the value obtained by dividing the charge capacity in the first cycle by the discharge capacity in the first cycle was expressed as a percentage to determine the first charge / discharge efficiency.

[Impedance measurement]
The impedance of each alkaline secondary battery was measured at 25 ° C. using a resistance measuring instrument “HiTESTER” manufactured by HIOKI at a frequency of 1 kHz. The impedance was measured for each of the three batteries, and the average value was calculated.

  Table 1 shows the evaluation results of the charging / discharging efficiency and the impedance. FIG. 3 is a graph showing the transition of the discharge capacity in the charge / discharge cycle, and FIG. 4 shows the discharge curves of the batteries of Example 1 and Comparative Example 1 obtained during the fifth cycle of discharge.

  As shown in Table 1, the alkaline secondary batteries of Examples 1 and 2 using a positive electrode material in which AB particles were mechanically fixed to the surface of silver oxide particles were obtained by simply mixing silver oxide particles and AB particles. The first charge / discharge efficiency was high and the impedance was low as compared with the batteries of Comparative Examples 1 and 2, which used.

  Further, as shown in FIG. 3, the alkaline secondary batteries of Examples 1 and 2 had a larger discharge capacity in each cycle than the batteries of Comparative Examples 1 and 2, and had excellent charge / discharge cycle characteristics.

  As shown in FIG. 4, the discharge curves of the batteries of Example 1 and Comparative Example 1 showed no significant difference except for the difference in discharge capacity, and were mechanically fixed to the surface of the silver oxide particles. No appearance of the carbon particles inhibiting the reaction of the silver oxide particles was observed.

Example 3
A positive electrode material was produced in the same manner as in Example 1 except that silver oxide (Ag ₂ O) particles containing no Bi were changed to silver oxide particles, and AB particles were mechanically fixed to the surfaces of the silver oxide particles. The positive electrode material is filled in a mold and pressed into a disk having a packing density of 5.7 g / cm ³ , a diameter of 5.17 mm and a height of 0.6 mm, thereby forming a positive electrode mixture molded product (positive electrode mixture). Agent layer).

  Then, an alkaline primary battery was produced in the same manner as in Example 1, except that the above-mentioned positive electrode mixture molded product was used and the anion conductive film was not used.

Comparative Example 3
A mixture of silver oxide particles and AB particles was prepared in the same manner as in Comparative Example 1 except that silver oxide (Ag ₂ O) particles containing no Bi were used, and in the same manner as in Example 3 except that this mixture was used. Thus, an alkaline primary battery was manufactured.

  The following evaluations were performed on the alkaline primary batteries of Example 3 and Comparative Example 3.

(Discharge capacity measurement)
For each alkaline primary battery, a constant current discharge was performed at a constant current of 1 mA until the voltage reached 1.0 V, and the discharge capacity was measured.

(Load characteristic evaluation)
Each of the alkaline primary batteries was discharged at a current value of 1 mA, 10 mA, and 25 mA, and a closed circuit voltage (CCV) 100 ms after the start of discharge was measured to evaluate load characteristics.

[Impedance measurement]
The impedance of each alkaline primary battery was measured by the same method as that of the battery of Example 1. The impedance was measured for each of the four batteries, and the average value was calculated.

  Table 2 shows the evaluation results of the discharge capacity, CCV at each discharge current, and impedance. FIG. 5 is a graph showing the relationship between the discharge current and CCV.

  As shown in Table 2 and FIG. 5, the alkaline primary battery of Example 3 using the positive electrode material in which AB particles were mechanically fixed to the surface of silver oxide particles was obtained by simply mixing silver oxide particles and AB particles. , The discharge capacity was large and the impedance was low as compared with the battery of Comparative Example 3 using. In addition, the battery of Example 3 had a lower CCV when the current value was increased and had better load characteristics than the battery of Comparative Example 3.

DESCRIPTION OF SYMBOLS 1 Alkaline battery 2 Outer can 3 Sealing plate 4 Positive electrode (a molded body of positive electrode mixture)
5 Negative electrode 6 Separator 7 Anion conductive membrane 8 Gasket

Claims (5)

An alkaline battery having a positive electrode, a negative electrode, and an alkaline electrolyte,
An alkaline battery, wherein the positive electrode has a positive electrode mixture layer containing a positive electrode material obtained by mechanically fixing carbon particles on the surface of silver oxide particles.   The alkaline battery according to claim 1, wherein the carbon particles contain carbon black.   The alkaline battery according to claim 1, wherein a ratio of the carbon particles in the positive electrode material is 0.1% to 3% by mass.   The alkaline battery according to any one of claims 1 to 3, wherein the positive electrode mixture layer further contains a conductive additive different from the carbon particles of the positive electrode material.   The alkaline battery according to claim 1, wherein the positive electrode mixture layer further contains insulating inorganic particles.

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