JP2019212391A - Alkaline secondary battery - Google Patents

Abstract

To provide an alkaline secondary battery which has the same configuration as an alkaline battery and an excellent cycle characteristic and in which an internal short circuit is hardly generated when charging.SOLUTION: The alkaline secondary battery includes: a positive electrode with a hollow cylindrical positive electrode mixture containing manganese oxide; a negative electrode containing zinc powder or zinc alloy powder; a separator; and an alkaline electrolyte. An anion conductive sheet bent into a cylindrical shape, whose ends are overlapped, is arranged at a position at which the positive electrode mixture and the negative electrode oppose to each other. An overlapping width of the ends of the anion conductive sheet is 0.7 mm.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an alkaline secondary battery that can be charged and discharged and can be used repeatedly.

  An alkaline battery using zinc as a negative electrode active material is used as a power source for various electronic devices, and various characteristics are required depending on its use. Until now, development has been promoted mainly for applications that require a relatively large current, such as digital cameras, cameras with flash, mobile TVs, and emergency chargers.

  For example, in Patent Document 1, the water content of any one of the positive electrode mixture, the positive electrode pellet, or the positive electrode is measured, and the amount of the alkaline electrolyte injected is determined according to the water content. It has been proposed to produce an alkaline battery that is excellent in heavy load discharge characteristics.

  In Patent Document 2, the zinc alloy powder contains 100 ppm or more of Al, and the water content in the battery system is 0.250 to 0.300 g per 1 g of the positive electrode active material (or 0.6 per g of zinc alloy powder). To 0.7 g), it is proposed to improve the moisture utilization efficiency at the time of battery discharge, to have excellent heavy load discharge characteristics, and to provide a battery in which gas generation at the time of overdischarge is suppressed. ing.

  On the other hand, the use of an alkaline battery as a rechargeable secondary battery has also been studied. In Patent Documents 3 and 4, a bobbin-type structure similar to that of an alkaline battery using manganese dioxide for the positive electrode and zinc for the negative electrode. A secondary battery having the following has been proposed.

JP 2013-45619 A JP 2010-118285 A JP 2000-31682 A Special table 2009-517805

  However, when a battery having the above-described configuration, which is normally used as a primary battery, is used as a secondary battery, an internal short circuit is likely to occur, and problems such as satisfactory charge / discharge cycle characteristics cannot be obtained. Is considered unsuitable.

  On the other hand, since the battery can be manufactured at a low cost, if a battery having sufficient charge / discharge cycle characteristics can be obtained with the same configuration as that of the alkaline dry battery, the battery has a high practical value.

  This invention is made | formed in view of the said situation, and it aims at preventing the internal short circuit at the time of charge of an alkaline dry battery, and making it usable as a secondary battery.

  The alkaline secondary battery of the present invention that can achieve the above object is a positive electrode including a hollow cylindrical positive electrode mixture containing manganese oxide, a negative electrode containing zinc powder or zinc alloy powder, a separator, An anion electrolyte sheet, having an anion conductive sheet that is bent into a cylindrical shape and overlapped at an end thereof, at a location where the positive electrode mixture and the negative electrode face each other, The overlapping width of the end portions is 0.7 mm or more.

  According to the present invention, it is possible to provide an alkaline secondary battery that hardly causes an internal short circuit during charging and has excellent cycle characteristics.

It is sectional drawing which shows an example of the alkaline secondary battery of this invention. It is the schematic which shows an example of a structure of the separator of the alkaline secondary battery of this invention. It is the schematic which shows another example of a structure of the separator of the alkaline secondary battery of this invention.

  The alkaline secondary battery of the present invention uses a hollow cylindrical positive electrode mixture containing manganese oxide for the positive electrode, zinc powder or zinc alloy powder for the negative electrode, as in the case of a normal alkaline dry battery, It is produced in a cylindrical shape using a separator and an alkaline electrolyte.

  In addition, the anion conductive sheet is arranged in a state where the positive electrode mixture and the negative electrode are opposed to each other so as to match the shape of the inner surface of the hollow cylindrical positive electrode mixture.

  When a normal alkaline battery is charged as it is after discharge, zinc dendrite is likely to be formed at the negative electrode, and if it enters the separator, problems such as internal short circuit occur, but the positive electrode mixture and the negative electrode face each other. By disposing an anion conductive sheet at the location to be made, it is possible to suppress the dendrite growth of zinc and prevent an internal short circuit. For this reason, cycling characteristics can improve and the practicality as a secondary battery can be improved.

  However, between the positive electrode mixture and the negative electrode, one end of the anion conductive sheet bent into a cylindrical shape is not connected to the other end so that a gap where no anion conductive sheet is present does not occur. It is necessary to overlap.

  In this case, due to the unevenness of the surface of the anion conductive sheet, the gap between the ends of the anion conductive sheet is slightly generated between the sheets, and therefore the width of the overlapping portion is small. The zinc dendrite grows through the gap, and an internal short circuit is likely to occur. For this reason, it is necessary to make the width | variety which overlaps the edge parts of an anion conductive sheet into 0.7 mm or more, and when considering the shift | offset | difference at the time of a process etc., it is preferable to set it as 1 mm or more. preferable.

  On the other hand, if the width of the overlapping part becomes too large, the reactivity of the positive electrode and the negative electrode facing each other through that part will be lower than other parts, and this will cause the battery discharge characteristics and cycle characteristics to deteriorate. The width of overlapping the end portions of the anion conductive sheet is preferably 7 mm or less, more preferably 5 mm or less, and particularly preferably 4 mm or less.

<Anion conductive sheet>
The anion conductive sheet used in the present invention is easy to permeate anions such as OH ⁻ ions directly involved in the ionic conductivity of the alkaline electrolyte, while Zn (OH) ₄ ²⁻ involved in the formation of zinc dendrites. It is a sheet that does not allow permeation of anions and has selective permeability to anions. From oxides, hydroxides, layered double hydroxides, phosphoric acid compounds, carbonic acid compounds, boric acid compounds, silicic acid compounds, and sulfuric acid compounds It can be constituted using at least one metal compound selected from the group consisting of oxides, hydroxides, layered double hydroxides, phosphoric acid compounds and sulfuric acid compounds, and layered double hydroxides are more preferred. Used.

  The anion conductive sheet includes, for example, a film formed by holding the metal compound particles with a resin serving as a binder and formed into a sheet, or a porous substrate such as a nonwoven fabric, and the metal compound particles and the binder. It is possible to form a sheet-like film filled with a composition containing a resin to become.

  The oxide is preferably cerium oxide or zirconium oxide, and may be a double oxide containing these metal elements. Examples of the hydroxide include cerium hydroxide and zirconium hydroxide.

  The layered double hydroxide is preferably a compound having anion exchange ability, such as hydrotalcite, manassete, moscoleite, stichtite, shoglenite, barbertite, pyroaulite, ionite, chloromagalminite, hydrocalumite. Hydrotalcite is more preferably used.

  Further, hydroxyapatite or the like is preferably used as the phosphoric acid compound, and ettringite is preferably used as the sulfuric acid compound.

  From the viewpoint of anion exchange capacity, hydrotalcite is preferable, and examples thereof include compounds represented by the following general formula (1).

{M ¹ _1-x M ² _x (OH) ₂ } (A ⁿ⁻ ) _{x / n} · mH ₂ O (1)

In the general formula (1), M ¹ represents Mg, Fe, Zn, Ni, Co, Cu, Ca, Li, and the like, M ² represents Al, Fe, Mn, and the like, A represents CO ₃ ^{2− and the} like. M is an integer of 0 or more, n is 2 or 3, and 0.2 ≦ x ≦ 0.4.

  The resin used as the binder is not particularly limited as long as it is a resin that is stable in an alkaline electrolyte. Polyvinylidene fluoride (PVDF), polytetrafluoroethylene (PTFE), vinylidene fluoride-hexafluoropropylene copolymer Polymer (PVDF-HFP), vinylidene fluoride-chlorotrifluoroethylene copolymer (PVDF-CTFE), vinylidene fluoride-tetrafluoroethylene copolymer (PVDF-TFE), vinylidene fluoride-hexafluoropropylene-tetrafluoro Fluorine resin such as ethylene copolymer (PVDF-HFP-TFE); polyolefin such as polyethylene (PE) and polypropylene (PP); styrene-butadiene copolymer, polybutadiene, polyisoprene, acrylonitrile-butadiene copolymer A conjugated diene-based resin; an aromatic vinyl resin such as polystyrene; a polymer having a polar group or a polar bond, such as a styrene-acrylic acid ester copolymer or an acrylic acid-acrylic acid ester copolymer (hereinafter, And the like.

  Examples of the polar polymer include polymers containing amino groups such as polyalkyleneimines (polyethyleneimine and the like); polymers containing ester bonds (ester groups) such as (alkoxy) polyalkylene glycol mono (meth) acrylates; Poly (meth) acrylic acid alkyl ester; alkali metal salt of poly (meth) acrylic acid (sodium salt, etc.), magnesium salt of poly (meth) acrylic acid, alkaline earth of poly (meth) acrylic acid Metal salts (such as calcium salts), poly (meth) acrylic acid ammonium salts, polymaleic acid alkali metal salts (such as sodium salts), polymaleic acid magnesium salts, polymaleic acid alkaline earth metal salts (such as calcium salts) , Ammonium salt of polymaleic acid, etc. , Polymers containing carboxylic acid salt (salt of carboxyl group), polyamides; and the like [the above "(meth) acrylic acid" is a representation summarizing the acrylic acid and methacrylic acid].

  The average particle size of the metal compound particles is preferably 5 nm or more, more preferably 10 nm or more, particularly preferably 100 nm or more, preferably 100 μm or less, and preferably 10 μm or less. Is more preferable, and it is especially preferable that it is 1 micrometer or less.

  The average particle diameter of the particles (powder) in the present specification is determined by dispersing these particles in a medium that does not dissolve the particles using a laser scattering particle size distribution meter (for example, “LA-920” manufactured by Horiba, Ltd.). The measured particle diameter (D50) at a cumulative frequency of 50% on a volume basis.

  In the anion conductive sheet, the ratio of the metal compound particles to the binder resin can be, for example, 10:90 to 99: 1 in mass ratio.

  In addition, the thickness of the anion conductive sheet is preferably 10 μm or more, more preferably 20 μm or more, and particularly preferably 40 μm or more, from the viewpoint of ensuring the above-mentioned effects better. However, if the anion conductive sheet is too thick, the occupied volume in the battery will increase and the capacity of the battery will be reduced, and the flexibility and flexibility will be lost, and the end will be overlapped by bending into a cylindrical shape. Since processing becomes difficult, the thickness is preferably 500 μm or less, and more preferably 250 μm or less.

  The anion conductive sheet is based on, for example, a paint prepared by dispersing the resin or the metal compound particles in a solvent such as water or N-methyl-2-pyrrolidone (the resin may be dissolved). When the film is applied to the surface of the material and formed, the film can be dried and then peeled off. The coating film may be subjected to a press treatment after drying. In addition, an anion conductive sheet including a porous substrate can be formed by filling the coating material inside a porous substrate such as a nonwoven fabric made of a resin such as polyethylene or polypropylene and drying it. . Also in this case, you may press-process after drying a coating film.

  Although the anion conductive sheet does not contain an alkaline electrolyte at this stage, the electrolyte can be contained inside the battery by absorbing the alkaline electrolyte injected into the battery. Alternatively, the anion conductive sheet after drying (or after the press treatment) may be immersed in an alkaline electrolyte to absorb the alkaline electrolyte in advance and then used for assembling the battery.

  The positive electrode, the negative electrode, and the alkaline electrolyte constituting the alkaline secondary battery of the present invention can be produced by the same process using the same material as that of a general-purpose alkaline dry battery.

  Hereinafter, an example of another configuration of the alkaline secondary battery of the present invention will be described.

<Negative electrode>
The negative electrode according to the alkaline secondary battery of the present invention uses a gelled negative electrode mixture (gelled negative electrode) having a zinc powder or zinc alloy powder as a negative electrode active material, a granular water-absorbing polymer, and an alkaline electrolyte. Configured.

  The zinc powder and zinc alloy powder preferably have a particle size adjusted so that the ratio of coarse particles and fine particles is reduced in order to prevent hydrogen gas generation and increase the uniformity of the charge / discharge reaction. Is preferably 120 μm or more, more preferably 150 μm or more, and on the other hand, it is preferably 200 μm or less, and more preferably 185 μm or less.

  The granular water-absorbing polymer is not particularly limited as long as it absorbs an alkaline electrolyte when forming the negative electrode mixture and swells, and can retain water necessary for the reaction in the negative electrode. Preferably, meth) acrylic acid or a crosslinked product thereof, poly (meth) acrylate or a crosslinked product thereof is preferably used. The poly (meth) acrylic acid and the poly (meth) acrylate may contain monomer components other than (meth) acrylic acid and (meth) acrylate. Examples of the poly (meth) acrylate include alkali metal salts and ammonium salts, and sodium salts and potassium salts are preferably used.

  By using a granular polymer having excellent liquid retention, the water-absorbing polymer can sufficiently retain moisture necessary for the reaction of the negative electrode active material.

  The average particle diameter of the granular water-absorbing polymer is preferably 50 μm or more, more preferably 100 μm or more, and more preferably 150 μm or more so that the negative electrode active material can be easily retained in the negative electrode. Most preferred. On the other hand, in order not to inhibit the discharge reaction, it is preferably 700 μm or less, more preferably 500 μm or less, and most preferably 300 μm or less.

  The alkaline electrolyte contained in the negative electrode is not particularly limited, and is the same as the electrolyte used in conventionally known alkaline dry batteries and alkaline secondary batteries (for example, potassium hydroxide, lithium hydroxide). Alkaline aqueous solution such as an aqueous solution of an alkali metal hydroxide such as sodium hydroxide) can be used, but it is an aqueous solution containing at least potassium hydroxide from the viewpoint of facilitating diffusion of the reaction product of the negative electrode. An aqueous solution having a concentration of 33% by mass or more is used.

Moreover, the negative electrode according to the alkaline secondary battery of the present invention may contain various additives as they are or in a state dissolved in the alkaline electrolyte. As the additive, an indium compound, a bismuth compound, a zinc compound, or the like is preferably used.
By containing an indium compound or bismuth compound in the negative electrode, In or Bi is segregated on the surface of the negative electrode active material, thereby suppressing the generation of discharge products on the surface of the negative electrode active material and the generation of gas due to corrosion of the negative electrode active material. Can be expected. Examples of the indium compound include indium oxide and indium hydroxide, and examples of the bismuth compound include bismuth oxide and bismuth hydroxide. The content of the indium compound or the bismuth compound is preferably 0.003 to 0.05 parts by mass with respect to 100 parts by mass of the negative electrode active material.

  Moreover, the effect which suppresses the gas generation | occurrence | production by corrosion of a negative electrode active material can be anticipated by making a negative electrode contain a zinc compound. As the zinc compound, for example, a compound such as zinc oxide, zinc silicate, zinc titanate, zinc molybdate can be used, and it is preferably contained in a state dissolved in an alkaline electrolyte, particularly zinc oxide. Are preferably used.

  The content of the zinc compound is preferably 1 to 4% by mass, more preferably 2.5 to 3.5% by mass when dissolved in an alkaline electrolyte.

  The negative electrode according to the alkaline secondary battery of the present invention preferably contains a thickener that is soluble in the alkaline electrolyte in order to make the viscosity at the time of gelation a suitable range. Examples of the thickener include celluloses such as poly (meth) acrylic acid, poly (meth) acrylate, carboxymethylcellulose, methylcellulose, hydroxypropylcellulose or salts thereof, and crosslinked branched poly (meth). Acrylic acid and cross-linked branched poly (meth) acrylate are preferably used. Examples of the salt of the poly (meth) acrylate and the cellulose include alkali metal salts and ammonium salts, and sodium salts and potassium salts are preferably used.

  The content of the thickener in the negative electrode is preferably 0.15 parts by mass or more with respect to 100 parts by mass of the negative electrode active material in order to sufficiently increase the viscosity of the negative electrode mixture. The amount is more preferably at least part by mass, and on the other hand, in order to impart a certain degree of fluidity to the negative electrode mixture, it is preferably at most 0.35 mass, more preferably at most 0.3 mass part.

  The total content of the granular water-absorbing polymer and the thickener is preferably 0.95 to 1.35 parts by mass with respect to 100 parts by mass of the negative electrode active material, and is 1 part by mass or more. More preferably, it is most preferably 1.05 parts by mass or more, more preferably 1.3 parts by mass or less, and most preferably 1.25 parts by mass or less.

  The negative electrode active material, the granular water-absorbing polymer, the alkaline electrolyte, the thickener and the like are mixed into a gel negative electrode mixture and used as the negative electrode of the alkaline secondary battery of the present invention. The content of the negative electrode active material in the negative electrode mixture is, for example, preferably 60% by mass or more, more preferably 65% by mass or more, and preferably 75% by mass or less. 70 mass% or less is more preferable.

<Positive electrode>
The positive electrode according to the alkaline secondary battery of the present invention includes, for example, a positive electrode active material, a conductive additive, and an alkaline electrolyte and a binder for molding to form a positive electrode mixture. It is formed by press molding into a ring shape.

  Manganese oxides typified by manganese dioxide and manganese oxyhydroxide are used as the positive electrode active material, and nickel oxides such as nickel oxyhydroxide and silver oxides such as silver oxide are oxidized with manganese to improve characteristics. You may mix and use. Further, it may be a composite compound containing an element such as lithium.

The positive electrode active material preferably has a BET specific surface area of 20 m ² / g or more, more preferably 25 m ² / g or more, in order to increase the reaction efficiency by setting the reaction area to a certain value or more.

On the other hand, it is desirable to improve the characteristics on the positive electrode side in accordance with the improvement of the characteristics of the negative electrode. By setting the BET specific surface area of the positive electrode active material to 40 m ² / g or less, preferably 35 m ² / g or less, It is desirable to improve moldability and increase the density of the mixture. Thereby, the filling amount of a positive electrode active material can be increased, the capacity | capacitance of a positive electrode can be enlarged, and it can respond to the characteristic improvement of a negative electrode.

  Note that the BET specific surface area of the positive electrode active material here is a specific surface area of the surface of the active material and the micropores, which is a surface area measured and calculated using the BET equation, which is a theoretical formula for multi-layer adsorption. . Specifically, it is a value obtained as a BET specific surface area by using a specific surface area measuring apparatus (for example, Macsorb HM model-1201 manufactured by Mounttech) by a nitrogen adsorption method.

  In addition, the average particle diameter of the positive electrode active material is preferably 45 μm or less, and more preferably 40 μm or less, in order to increase the reaction area to a certain level or more and increase the reaction efficiency. On the other hand, in order to improve the moldability of the positive electrode mixture and increase the density of the mixture, it is preferably 30 μm or more, and more preferably 33 μm or more.

  For example, graphite, ketjen black, acetylene black, or the like can be used as the conductive additive related to the positive electrode. The amount of the conductive auxiliary agent in the positive electrode mixture is preferably 3 parts by mass or more, more preferably 4.5 parts by mass or more with respect to 100 parts by mass of the positive electrode active material, from the viewpoint of improving conductivity. , 6 parts by mass or more is most preferable. On the other hand, in order to ensure the capacity of the positive electrode, it is preferably 10 parts by mass or less, more preferably 8.5 parts by mass or less, and more preferably 7 parts by mass or less with respect to 100 parts by mass of the positive electrode active material. Most preferred.

  As the binder for the positive electrode, for example, polytetrafluoroethylene, polyvinylidene fluoride, styrene butadiene rubber, or the like can be used. The amount of the binder in the positive electrode mixture is preferably 0.1 to 1% by mass, for example.

  Examples of the alkaline electrolyte used for the positive electrode include an alkaline aqueous solution in which an alkali metal hydroxide such as potassium hydroxide, sodium hydroxide, lithium hydroxide or the like is dissolved in water, or a zinc oxide added thereto. Although used, a potassium hydroxide aqueous solution is more preferable from the viewpoint of enhancing the discharge characteristics of the battery. For example, in the case of potassium hydroxide, the concentration of the alkali metal hydroxide in the electrolytic solution is preferably 40 to 60% by mass. When zinc oxide is used, the concentration is 1.0 to It is preferable that it is 4.0 mass%.

  In addition, the average particle diameter used in the present invention is a value expressed as a volume average particle diameter (D50) obtained by measurement of particle size distribution using a particle size distribution meter.

<Electrolyte>
In addition to the use for the positive electrode and the negative electrode, as the alkaline electrolyte for injecting into the battery, for example, the alkaline electrolyte for absorbing the separator, as in the electrolyte for the positive and negative electrodes, An alkaline aqueous solution composed of an aqueous solution of an alkali metal hydroxide such as potassium, sodium hydroxide or lithium hydroxide, or a solution in which zinc oxide is added thereto can be used, but it is the same as the alkaline electrolyte used for the negative electrode. A configuration is preferable.

<Separator>
In the alkaline secondary battery of the present invention, at least the anion conductive sheet functions as a separator, but it is desirable to provide an electrolyte holding layer separately from the anion conductive sheet in order to increase the holding ability of the electrolyte.

  There is no restriction | limiting in particular as said electrolyte solution holding layer, What is necessary is just to use what is used as a separator with a general purpose alkaline battery. For example, non-woven fabric mainly composed of vinylon and rayon, vinylon / rayon non-woven fabric (vinylon / rayon blended paper), polyamide non-woven fabric, polypropylene non-woven fabric, polyolefin / rayon non-woven fabric, vinylon paper, vinylon linter pulp paper, vinylon mercerized pulp paper, etc. Can be used. Alternatively, a hydrophilic microporous polyolefin film (such as a microporous polyethylene film or a microporous polypropylene film), a cellophane film, or a laminate of vinylon / rayon mixed paper may be used as the electrolyte retaining layer. .

  The anion conductive sheet and the electrolyte solution holding layer can be integrated, for example, a paint for forming the anion conductive sheet is filled on one side of the nonwoven fabric, and the other side of the nonwoven fabric is empty. By leaving the holes, an anion conductive sheet is formed on one side of the same nonwoven fabric, and a separator in which the other side is an electrolyte solution holding layer can be obtained.

<Structure of alkaline secondary battery>
The structure of the alkaline secondary battery of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing an example of the alkaline secondary battery of the present invention. The alkaline secondary battery in FIG. 1 has a positive electrode 2 (positive electrode mixture formed body) formed in a ring shape in an outer can 1 made of metal (such as Ni-plated iron or stainless steel). A cup-shaped separator 3 is disposed on the inner side, and an alkaline electrolyte (not shown) is injected from the inner side of the separator 3. Furthermore, the negative electrode 4 (gelled negative electrode mixture) containing a negative electrode active material (zinc powder or zinc alloy powder) is filled inside the separator 3. 1b in the outer can 1 is a positive electrode terminal. A metal negative electrode terminal plate 7 is disposed on the opening end 1a of the outer can 1 through an outer peripheral edge 62 of the resin sealing body 6. The open end 1a is folded inward and sealed. In addition, in order to insulate the outer can 1 and the negative electrode terminal plate 7, the insulating plate 8 is arrange | positioned among these.

  A negative electrode current collector rod 5 made of metal (such as brass plated with Sn) is welded to the negative electrode terminal plate 7 at its head, and the negative electrode current collector rod 5 is provided at the central portion 61 of the sealing body 6. The inserted through hole 64 is inserted into the negative electrode 4. The resin sealing body 6 is formed with an explosion-proof thin portion 63. When gas is generated in the battery at the time of a short circuit, the thin portion 63 of the sealing body 6 is preferentially cleaved, and the gas moves to the negative electrode terminal plate 7 side from the generated fissure. The negative terminal plate 7 is provided with gas vent holes (not shown), and the gas in the battery is discharged out of the battery through these gas vent holes. Examples of the resin constituting the resin sealing body 6 include nylon 66 and the like.

  In the battery of this embodiment, as a means for preventing the deformation of the negative electrode terminal plate 7 at the time of sealing and supporting the sealing body 6 from the inside, a supporting means such as a metal washer (a disk-shaped metal plate) is not separately provided, By using the negative electrode terminal plate 7, the volume occupied by the sealing portion 10 can be reduced to increase the volume of the trunk portion 20 that can accommodate the power generation element, and the filling amount of each mixture of the positive electrode 2 and the negative electrode 4 can be increased. Can do a lot.

  Moreover, the detail of the structure of the said cup-shaped separator 3 is shown to Fig.2 (a)-(c). The cup-shaped separator 3 includes a side surface portion 3a and a bottom portion 3b, and can be configured by combining a member constituting the side surface portion 3a and a member constituting the bottom portion 3b. That is, as shown in FIG. 2A, a rectangular anion conductive sheet A constituting the side surface portion 3a and a circular anion conductive sheet B constituting the bottom portion 3b are prepared. ), The anion conductive sheet A is bent into a cylindrical shape, one end is overlaid on the other end, and then combined with the circular anion conductive sheet B to form a cup-shaped separator 3. Can be formed.

  At this time, the width: t of the overlapping portion of the anion conductive sheet A is adjusted to be 0.7 mm or more as described above.

  FIG. 2C shows an example in which an electrolyte solution holding layer is provided and the side surface portion 3a is constituted by the anion conductive sheet A and the electrolyte solution holding layer 3c. The electrolyte solution holding layer 3c can be formed on the outer side (positive electrode side) or the inner side (negative electrode side) of the anion conductive sheet, but in order to easily suppress the dendrite growth of zinc, It is desirable to provide it outside the anion conductive sheet.

  In the above example, the anion conductive sheet is also used as the member constituting the bottom 3b. However, the bottom 3b may be composed of a member other than the anion conductive sheet, and the bottom 3b may be formed using another member such as the above-mentioned nonwoven fabric. It can also be formed.

  3 (a) to 3 (c) show another aspect of the structure of the cup-shaped separator 3 described above. The cup-shaped separator 3 shown in FIG. 3 has a bottom 3b formed by bending an opening end of a member constituting the side surface 3a. For example, as shown in FIG. 3 (a), a rectangular anion conductive sheet constituting the side surface portion 3a is prepared, and as shown in FIG. 3 (b), the anion conductive sheet is bent into a cylindrical shape, After superposing one end portion on the other end portion, as shown in FIG. 3C, one open end portion is bent inward to form a bottom portion 3b to form a cup-shaped separator 3. be able to.

  In addition, when laminating | stacking an anion conductive sheet and an electrolyte solution holding layer and comprising the separator 3, at least one opening edge part is comprised among the anion conductive sheet and electrolyte solution holding layer which comprise the side part 3a. The bottom 3b may be formed by bending inward. When only one member is used as a constituent member of the bottom portion 3b, the height of the member can be made higher than the height of the other member, and the excess portion can be bent inward to form the bottom portion 3b. .

  Also in this case, in order to easily suppress the dendrite growth of zinc, it is desirable to provide an electrolyte solution holding layer outside the anion conductive sheet.

  The produced cup-shaped separator 3 absorbs the alkaline electrolyte described above, and further accommodates the negative electrode mixture therein to assemble the battery.

(Example 1)
<Formation of positive electrode mixture>
Manganese dioxide (average particle size: 36.5 μm, BET specific surface area: 31 m ² / g), graphite, zinc oxide, polytetrafluoroethylene powder and alkaline electrolyte for preparing positive electrode mixture (56% by mass of potassium hydroxide, And an aqueous solution containing 2.9% by mass of zinc oxide) at a mass ratio of 100: 7.7: 0.2: 0.2: 6.9 at a temperature of 50 ° C. to prepare a positive electrode mixture did.

<Formation of negative electrode mixture>
A zinc alloy containing 0.01% by mass (100 ppm) of Al, 0.01% by mass (100 ppm) of Bi, 0.03% by mass (300 ppm) of In, and 0.0005% by mass (5 ppm) of Mg. Powder, a crosslinked product of granular sodium polyacrylate having an average particle size of 500 μm, an alkaline electrolyte for preparing polyacrylic acid and a negative electrode mixture (34% by mass of potassium hydroxide, and 2.% of zinc oxide). 9 mass% aqueous solution) was mixed at a mass ratio of 100: 0.91: 0.24: 48.1 to prepare a gelled negative electrode mixture.
The zinc alloy powder has an average particle size of 170 μm, the proportion of the powder that passed through the 50 mesh sieve is 98.7% by mass of the whole powder, and the proportion of the powder that passed through the 200 mesh sieve However, it was 11 mass% of the whole powder.

<Preparation of anion conductive sheet>
An aqueous paint containing 100 parts by weight of hydrotalcite having an average particle size of 0.2 μm, 40 parts by weight of styrene-2-ethylhexyl acrylate copolymer, and 2 parts by weight of poly N-vinylacetamide was prepared. The anion conductive sheet having a thickness of 100 μm was prepared by filling a polypropylene nonwoven fabric, drying, and pressing.

<Production of battery>
As an outer can, an outer can 1 for an AA alkaline battery made of a killed steel plate with a matte Ni plating on the surface and having the shape shown in FIG. 1 was prepared. The outer can 1 has a sealing portion 10 having a thickness of 0.25 mm and a body portion 20 having a thickness of 0.16 mm. Further, in order to prevent the positive terminal 1b from being dented when the battery is dropped, The thickness of the can is the same as that of the sealing part. Using the outer can 1, an alkaline secondary battery was produced as follows.

The positive electrode mixture: 11.1 g was inserted into the outer can 1 and pressure-formed into a bobbin shape (hollow cylindrical shape). Inner diameter: 9.1 mm, outer diameter: 13.7 mm, height: 13.9 mm The three positive electrode mixture compacts (density: 3.28 g / cm ³ ) were stacked. Next, in order to improve the adhesion between the outer can 1 and the sealing body 6 at a position of 3.5 mm in the height direction from the opening end of the outer can 1, the inner side of the outer can 1 up to this groove position. A pitch was applied.

The anion conductive sheet is cut into a size of 51 × 31 mm, bent into a cylindrical shape so that the end overlaps with a width of 3 mm, and on the outside, acetalized with a thickness of 100 μm and a basis weight of 30 g / m ² A cup-shaped separator in which one end is closed as shown in FIG. 3 (c) after a non-woven fabric made of vinylon and tencel is overlapped and wound into a cylindrical shape, and then the bottom portion is folded and heat-sealed. It was set to 3.

  That is, in this separator 3, the side surface portion was constituted by the non-woven fabric serving as the electrolyte solution holding layer and the anion conductive sheet, and the bottom portion was constituted by the same member as the side surface portion.

  This separator 3 is loaded inside the positive electrode 1 inserted into the outer can 1 and is contained in an alkaline electrolyte (34% by mass of potassium hydroxide and 2.9% by mass of zinc oxide) for absorbing the separator. A negative electrode 4 was prepared by injecting 1.8 g of an aqueous solution into the separator and filling the negative electrode mixture: 5.6 g into the separator 3.

  After filling the power generation element, the negative electrode current collector rod 5, which has a tin-plated brass surface and is combined with a nylon 66 sealing body 6, is inserted into the central portion of the negative electrode 4, and the open end of the outer can 1 The AA alkaline secondary battery shown in FIG. 1 was produced by caulking from the outside of 1a by a spinning method. Here, the negative electrode current collecting rod 5 used was previously attached by welding to a negative electrode terminal plate 7 made of nickel-plated steel plate having a thickness of 0.4 mm formed by stamping and pressing. An insulating plate 8 was mounted between the open end of the outer can 1 and the negative electrode terminal plate 7 to prevent a short circuit.

(Example 2)
Alkaline secondary as in Example 1 except that the anion conductive sheet was cut into a size of 51 × 34 mm, bent into a cylindrical shape with the end overlapping with a width of 6 mm, and used for the production of the separator. A battery was produced.

(Example 3)
Alkaline secondary as in Example 1, except that the anion conductive sheet was cut into a size of 51 × 38 mm, bent into a cylindrical shape with the end overlapping with a width of 10 mm, and used for the production of the separator. A battery was produced.

(Comparative Example 1)
Except that the anion conductive sheet was cut into a size of 51 × 28.5 mm, bent into a cylindrical shape so that the end overlapped with a width of 0.5 mm, and used for the production of the separator, the same as in Example 1. Thus, an alkaline secondary battery was produced.

(Comparative Example 2)
Alkali secondary as in Example 1 except that an anion conductive sheet was not used and a non-woven fabric composed of 100 μm thick acetalized vinylon and tencel was overlapped to form a cylindrical cup-shaped separator. A battery was produced.

<Evaluation of discharge characteristics>
The alkaline secondary batteries of Examples 1 to 3 and Comparative Examples 1 to 2 were discharged at a current of 250 mA until the battery voltage dropped to 0.9 V, the initial discharge capacity was measured, and the discharge characteristics were evaluated.

<Evaluation of cycle characteristics>
For the battery whose initial discharge capacity was measured, a cycle until the discharge capacity was reduced to 50% of the initial discharge capacity by repeatedly charging with a current of 250 mA and discharging with a current of 250 mA (discharge end voltage: 0.9 V). The cycle characteristics were evaluated by measuring the number.

  The alkaline secondary batteries of Examples 1 to 3, in which the anion conductive sheet bent in a cylindrical shape is disposed at a position where the positive electrode mixture and the negative electrode face each other, and the overlapping width of the end portions is 0.7 mm or more, Compared to the alkaline secondary battery of Comparative Example 1 in which the overlapping width is narrower than 0.7 mm and the alkaline secondary battery of Comparative Example 2 in which a nonwoven fabric is doubled and a separator is used without using an anion conductive sheet, charging and discharging are performed. The cycle characteristics could be improved, and the practicality of the secondary battery designed with the same configuration as the alkaline battery could be improved.

DESCRIPTION OF SYMBOLS 1 Exterior can 1a Open end 2 Positive electrode 3 Separator 4 Negative electrode 5 Negative electrode current collector rod 6 Resin sealing body 7 Negative electrode terminal plate 8 Insulating plate 61 Central portion of sealing body 62 Outer peripheral edge portion of sealing body 63 Thin-wall portion for explosion protection 64 Through hole

Claims (7)

An alkaline secondary battery having a positive electrode including a hollow cylindrical positive electrode mixture containing manganese oxide, a negative electrode containing zinc powder or zinc alloy powder, a separator, and an alkaline electrolyte,
In the place where the positive electrode mixture and the negative electrode face each other, the anion conductive sheet is bent into a cylindrical shape and the end portions thereof are overlapped,
An alkaline secondary battery, wherein an overlapping width of end portions of the anion conductive sheet is 0.7 mm or more.   The alkaline secondary battery according to claim 1, wherein an overlapping width of end portions of the anion conductive sheet is 7 mm or less.   The alkaline secondary battery according to claim 1, further comprising an electrolyte solution holding layer between the anion conductive sheet and the positive electrode mixture.   The alkaline secondary battery according to claim 3, comprising a nonwoven fabric as the electrolyte solution holding layer. The separator is formed in a cup shape having a side part and a bottom part,
The alkaline secondary battery in any one of Claims 1-4 comprised by combining the member which comprises the said side part, and the member which comprises the said bottom part.   The alkaline battery according to claim 1, wherein the anion conductive sheet contains a layered double hydroxide.   The alkaline battery according to claim 6, wherein the anion conductive sheet contains hydrotalcite.

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