JP2018060636A - Alkaline battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide alkaline batteries of an inside-out structure, in which a negative electrode can be prevented from outflowing to a positive electrode side due to falling of batteries and shock and vibration applied to batteries during transportation.SOLUTION: An alkaline battery includes: a hollow cylindrical positive electrode 2; a gel-like negative electrode 3 disposed in a hollow portion of the positive electrode 2; a separator 4 disposed between the positive electrode 2 and the negative electrode 3; and an alkaline electrolyte contained in the positive electrode 2, the negative electrode 3, and the separator 4. The negative electrode 3 contains a zinc-containing negative electrode active material and terephthalic acid. The content of the terephthalic acid in the negative electrode 3 is 0.05-1 pts.mass per 100 pts.mass of the negative electrode active material. The thickness of the separator is 220-390 μm.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an alkaline battery having an inside-out type structure.

  Alkaline batteries (alkali manganese batteries) are widely used because they have a large capacity and can extract a large current. An alkaline dry battery having an inside-out structure includes a hollow cylindrical positive electrode, a gelled negative electrode disposed in the hollow part of the positive electrode, a separator disposed between the positive electrode and the negative electrode, a positive electrode, a negative electrode, and And an alkaline electrolyte contained in the separator (see Patent Document 1). Various studies have been conducted on batteries having the above structure.

  For example, it has been proposed to add a fiber material to a negative electrode containing zinc particles as a negative electrode active material (see Patent Document 1). For example, rayon fiber or vinylon fiber is used as the fiber material. Since the zinc particles are surrounded by the fiber material, the zinc particles contained in the negative electrode are prevented from being unevenly distributed when an impact is applied to the battery due to the fall of the battery, and the zinc particles or between the zinc particles and the negative electrode current collector The contact state with is kept good.

JP-A-5-129017

  However, when the battery is dropped or transported, the separator buckles as the negative electrode flows (scatters) due to strong impact or vibration applied to the battery, and the negative electrode flows out to the positive electrode, causing an internal short circuit and generating heat. There is a problem of doing. The technique proposed in Patent Document 1 cannot sufficiently suppress the outflow of the negative electrode to the positive electrode due to the buckling of the separator.

  On the other hand, it is required to reduce the thickness of the separator for the purpose of increasing the capacity and reducing the internal resistance by increasing the filling amount of the positive electrode active material and the negative electrode active material. However, the thinner the separator, the lower the strength of the separator, and the more likely the outflow of the negative electrode to the positive electrode due to the buckling of the separator occurs.

  An object of the present invention is to suppress the occurrence of an internal short circuit due to the outflow of the negative electrode to the positive electrode side and the accompanying heat generation of the battery in an alkaline battery having an inside-out type structure.

  One aspect of the present invention includes a hollow cylindrical positive electrode, a gelled negative electrode disposed in a hollow portion of the positive electrode, a separator disposed between the positive electrode and the negative electrode, the positive electrode, the negative electrode, And the alkaline electrolyte contained in the separator, the negative electrode includes a negative electrode active material containing zinc and terephthalic acid, and the content of the terephthalic acid in the negative electrode is 100 masses of the negative electrode active material. It is 0.05-1 mass part per part, and the thickness of the said separator is related with the alkaline dry battery which is 220-390 micrometers.

  According to the present invention, in an inside-out type alkaline dry battery including a thin separator, it is possible to suppress the occurrence of an internal short circuit due to the outflow of the negative electrode to the positive electrode side and the accompanying heat generation of the battery. Reliability can be improved.

It is a front view which makes some cross sections the alkaline dry battery in one Embodiment of this invention. It is the schematic which shows an example of the separator with which an alkaline battery is equipped. It is the schematic which shows another example of the separator with which an alkaline battery is equipped.

  The alkaline dry battery according to one embodiment of the present invention has an inside-out type structure. That is, a hollow cylindrical positive electrode, a gelled negative electrode disposed in a hollow portion of the positive electrode, a separator disposed between the positive electrode and the negative electrode, a positive electrode, a negative electrode, and an alkaline electrolyte contained in the separator Is provided. The gelled negative electrode contains a negative electrode active material containing zinc and terephthalic acid. The content of terephthalic acid in the negative electrode is 0.05 to 1 part by mass per 100 parts by mass of the negative electrode active material, and the thickness of the separator is 220 to 390 μm. In addition, in this specification, when only described as the thickness of the separator, this means the thickness of the separator in a swollen state containing the electrolytic solution. In addition, when a separator is formed by winding a single sheet in multiple layers or by stacking a plurality of sheets, the thickness of the separator is the total thickness of the rolled (overlaid) sheets. Point to.

  In this embodiment, by adding 0.05 to 1 part by mass of terephthalic acid to the negative electrode per 100 parts by mass of the negative electrode active material, moderate elasticity is imparted to the negative electrode, and the fluidity of the negative electrode is sufficiently reduced. For this reason, it becomes difficult for the negative electrode to flow (scatter) due to impact or vibration applied to the battery when the battery is dropped or transported. Therefore, even when the thickness of the separator is as thin as 220 to 390 μm, the outflow of the negative electrode to the positive electrode due to the buckling of the separator accompanying the flow of the negative electrode can be sufficiently suppressed. As a result, the occurrence of an internal short circuit due to the outflow of the negative electrode to the positive electrode side and the accompanying heat generation of the battery can be prevented, and the reliability of the battery can be improved.

When the content of terephthalic acid in the negative electrode is less than 0.05 parts by mass per 100 parts by mass of the negative electrode active material, the effect of including terephthalic acid in the negative electrode cannot be sufficiently obtained. When the content of terephthalic acid in the negative electrode is more than 1 part by mass per 100 parts by mass of the negative electrode active material, the viscosity of the negative electrode increases, and the filling property of the negative electrode into the hollow part of the positive electrode decreases.
The content of terephthalic acid in the negative electrode is preferably 0.3 to 1 part by mass and more preferably 0.5 to 1 part by mass per 100 parts by mass of the negative electrode active material.

Since the thickness of the separator is 220 to 390 μm, the filling amount (negative electrode capacity) of the negative electrode can be sufficiently ensured, and the internal resistance can be sufficiently reduced.
When the thickness of the separator is less than 220 μm, the strength of the separator is reduced, so that the separator is buckled by impact or vibration applied to the battery, and accordingly, the negative electrode flows out to the positive electrode side. When the thickness of the separator exceeds 390 μm, the thickness of the separator increases, so that the amount of negative electrode filled into the hollow portion of the positive electrode decreases, and the negative electrode capacity decreases.

  The thickness of the separator is more preferably 220 to 260 μm. Even when the thickness of the separator is as very thin as 220 to 260 μm, by containing a specific amount of terephthalic acid in the negative electrode, the outflow to the positive electrode side of the negative electrode due to the buckling of the separator accompanying the flow of the negative electrode can be sufficiently suppressed. it can. By making the separator thinner, the filling amount of the negative electrode, that is, the negative electrode capacity can be further increased. In addition, since the distance between the positive electrode and the negative electrode is further reduced, the internal resistance of the battery can be further reduced.

  Powdered terephthalic acid is difficult to dissolve in the gelled negative electrode. In the negative electrode, the very surface of the terephthalic acid particles is only slightly dissolved, and most of the terephthalic acid particles are present without being dissolved.

The average particle diameter of the terephthalic acid particles in the negative electrode is preferably 50 to 300 μm. When the average particle diameter of the terephthalic acid particles is 50 to 300 μm, the negative electrode can be provided with good elasticity and the negative electrode can be filled. Therefore, the flow of the negative electrode due to the impact or vibration applied to the battery when the battery is dropped or transported is further suppressed, and a slight internal short circuit is less likely to occur. More specifically, a battery voltage drop of 5 mV or less due to impact or vibration applied to the battery when the battery is dropped or transported (a small internal short circuit that does not cause heat generation of the battery due to scattering of a small amount of negative electrode to the positive electrode side). Generation) can be suppressed, and the reliability of the battery can be further enhanced.
The average particle size of the terephthalic acid particles in the negative electrode is more preferably 50 to 150 μm.

The average particle diameter of the terephthalic acid particles in the negative electrode is determined, for example, by the following method.
First, after disassembling the battery and taking out the gelled negative electrode, the negative electrode active material is removed from the negative electrode by centrifugation to obtain a mixture of gelling agent and terephthalic acid particles. The resulting mixture is dried and then observed using an optical microscope to randomly select ten terephthalic acid particles. Then, the particle size of each particle is measured, two measured values are deleted in order from the largest measured value, and the two measured values are deleted in order from the smallest measured value, and the average value of the remaining six measured values is determined as terephthalic acid in the negative electrode. It can obtain | require as an average particle diameter of this particle | grain.

  The separator includes, for example, a sheet wound along the inner surface of the hollow portion of the hollow cylindrical positive electrode. In this case, from the viewpoint of the function and strength as a separator, the separator preferably has a portion P1 where one end portion of the sheet winding start and the other end portion of the sheet winding end overlap each other. The overlapping portion P1 has a length L1 in a cross section perpendicular to the axial direction (X direction in FIG. 1) of the positive electrode of the separator. For example, one sheet may be wound in a single layer or multiple layers, and a portion P1 may be provided in which one end portion of the sheet winding start and the other end portion of the sheet winding end overlap each other. Here, the thickness of a separator points out the thickness of parts other than the part P1 of a separator.

  Here, FIG. 2 is a schematic view schematically showing an example in which a separator is formed by winding a sheet twice. FIG. 2 shows a cross section perpendicular to the axial direction (X direction in FIG. 1) of the positive electrode of the separator. The separator is configured by winding the sheet 14a twice, and has a portion P1 in which one end portion of the winding start and the other end portion of the winding end overlap each other with a length L1.

In the cross section perpendicular to the axial direction (X direction in FIG. 1) of the positive electrode of the separator, the length L1 of the overlapping portion P1 is preferably 6 mm or less. For example, when the length L1 of the overlapping portion P1 is 3 mm, one end portion of the winding start and the other end portion of the winding end overlap each other with a length of 3 mm. In the portion P1, the thickness of the separator is It means that it is getting bigger.
Further, the length L1 of the overlapping portion P1 may be 0 mm. The length L1 of the overlapping portion P1 being 0 mm means that one end edge of the winding start is coincident with the other end edge of the winding end, and the thickness of the separator is constant.

When the length L1 of the overlapping portion P1 is 0 to 6 mm, the strength of the separator can be sufficiently increased. For this reason, it is possible to further suppress the outflow of the negative electrode to the positive electrode due to the buckling of the separator accompanying the flow of the negative electrode, and to suppress a slight internal short circuit accompanied by a decrease in the battery voltage of 5 mV or less. The reliability can be further increased.
The length L1 of the overlapping portion P1 is more preferably 1 to 5 mm, still more preferably 2 to 4 mm.

  The separator includes, for example, a plurality of sheets sequentially arranged along the inner surface of the hollow portion of the positive electrode. In this case, from the viewpoint of the function and strength as a separator, the separator preferably has a portion P2 where the ends of adjacent sheets overlap each other. The overlapping portion P2 has a length L2 in a cross section perpendicular to the axial direction (X direction in FIG. 1) of the positive electrode of the separator. Here, the thickness of a separator points out the thickness of parts other than the part P2 of a separator.

  More specifically, in the cross section perpendicular to the axial direction (X direction in FIG. 1) of the positive electrode of the separator, the length A corresponds to the length corresponding to the length of 1 / n circumference, and further from both ends of the portion A. A separator for one round may be configured by sequentially arranging n sheets of a sheet having a portion B extended by an amount corresponding to L2 / 2 along the inner surface of the hollow portion of the positive electrode. n is an integer of 2 to 4, for example. It is preferable that the separator for one round has a portion P2 where the end portions of the adjacent sheets overlap each other. In this case, the separator for one round has n portions P2 that overlap with each other with the length L2. From the viewpoint of strength, a plurality of separators for one round may be used to overlap these multiple layers. In this case, from the viewpoint of balance of strength, it is preferable to arrange the separators for each round so that the overlapping portions P2 of the separators for each round do not overlap each other.

  Here, FIG. 3 is a schematic view schematically showing an example in which n = 2 and two separators for one round are used and these are overlapped. FIG. 3 shows a cross section perpendicular to the axial direction (X direction in FIG. 1) of the positive electrode of the separator. In a cross section perpendicular to the axial direction (X direction in FIG. 1) of the positive electrode of the separator, a portion A corresponding to a length corresponding to ½ circumference and a length L2 / 2 from both ends of the portion A, respectively. Two sheets 24a and 24b each having a portion B extended by an amount are sequentially arranged along the inner surface of the hollow portion of the positive electrode to form a separator 24 for one round. The separator 24 for one round has a portion P2 where the ends of the adjacent sheets 24a and 24b overlap each other. The separator 24 for one round has two portions P2 that overlap with each other with a length L2. Similarly, the separator 34 for one round is comprised by the two sheets 34a and 34b. A separator 34 is arranged inside the separator 24, and the separators 24, 34 are arranged at the center of one separator portion A of the separators 24, 34 (the portion other than the overlapping portion P2) and the other separator. It arrange | positions so that the overlapping part P2 may overlap.

In the cross section perpendicular to the axial direction (X direction in FIG. 1) of the positive electrode of the separator, the length L2 of the overlapping portion P2 is preferably 6 mm or less. For example, the length L2 of the overlapping portion P2 being 3 mm means that the end portions of the adjacent sheets overlap each other with a length of 3 mm, and the thickness of the separator is increased in the portion P2.
Further, the length L2 of the overlapping portion P2 may be 0 mm. The length L2 of the overlapping portion P2 being 0 mm means that in the sheets adjacent to each other arranged along the hollow portion of the positive electrode, the edge of one sheet coincides with the edge of the other sheet. This means that the thickness of the separator is constant.

When the length L2 of the overlapping portion P2 is 0 to 6 mm, the strength of the separator can be sufficiently increased. For this reason, it is possible to further suppress the outflow of the negative electrode to the positive electrode due to the buckling of the separator accompanying the flow of the negative electrode, and to suppress a slight internal short circuit accompanied by a decrease in the battery voltage of 5 mV or less. The reliability can be further increased.
The length L2 of the overlapping portion P2 is more preferably 1 to 5 mm, and still more preferably 2 to 4 mm.

  Hereinafter, the alkaline battery according to the present embodiment will be described in detail with reference to the drawings. In addition, this invention is not limited to the following embodiment. Moreover, it can change suitably in the range which does not deviate from the range which has the effect of this invention. Furthermore, combinations with other embodiments are possible.

  FIG. 1 is a front view of a cross section of a horizontal half of an alkaline battery according to an embodiment of the present invention. As shown in FIG. 1, the alkaline battery includes a hollow cylindrical positive electrode 2, a negative electrode 3 disposed in the hollow portion of the positive electrode 2, a separator 4 disposed therebetween, and an alkaline electrolyte (not shown). Are housed in a bottomed cylindrical battery case 1 that also serves as a positive electrode terminal.

The positive electrode 2 is disposed in contact with the inner wall of the battery case 1. The positive electrode 2 contains manganese dioxide and an alkaline electrolyte.
The hollow portion of the positive electrode 2 is filled with a gelled negative electrode 3 via a separator 4. The negative electrode 3 usually contains an alkaline electrolyte and a gelling agent in addition to the negative electrode active material containing zinc and terephthalic acid. The content of terephthalic acid in the negative electrode 3 is 0.05 to 1 part by mass per 100 parts by mass of the negative electrode active material.

  The separator 4 has a bottomed cylindrical shape and includes an electrolytic solution. The separator 4 includes a cylindrical separator 4a and a bottom paper 4b. The separator 4 a is disposed along the inner surface of the hollow portion of the positive electrode 2 and separates the positive electrode 2 and the negative electrode 3. Therefore, the separator disposed between the positive electrode and the negative electrode means the cylindrical separator 4a. The bottom paper 4 b is disposed at the bottom of the hollow portion of the positive electrode 2 and separates the negative electrode 3 and the battery case 1. The thickness of the separator 4a is 220 to 390 μm.

  The opening of the battery case 1 is sealed by a sealing unit 9. The sealing unit 9 includes a gasket 5, a negative electrode terminal plate 7 that also serves as a negative electrode terminal, and a negative electrode current collector 6. The negative electrode current collector 6 is inserted into the negative electrode 3. The negative electrode current collector 6 has a nail-like shape having a head portion and a body portion, and the body portion is inserted into a through hole provided in the central cylinder portion of the gasket 5, so that the negative electrode current collector 6 The head is welded to the flat portion at the center of the negative terminal plate 7. The opening end portion of the battery case 1 is caulked to the flange portion of the peripheral edge portion of the negative electrode terminal plate 7 via the outer peripheral end portion of the gasket 5. The outer surface of the battery case 1 is covered with an exterior label 8.

  By including terephthalic acid in the negative electrode 3, moderate elasticity is imparted to the negative electrode 3, and the fluidity of the negative electrode 3 is sufficiently reduced. For this reason, it becomes difficult for the negative electrode 3 to flow (scatter) to the gasket 5 side due to impact or vibration applied to the battery when the battery is dropped or transported. Therefore, even if the thickness of the separator 4a is as thin as 220 to 390 μm, the separator 4a (the end portion on the gasket 5 side) buckles due to the flow (scattering) of the negative electrode 3 to the gasket 5 side to the positive electrode 2 side of the negative electrode 3. Outflow is sufficiently suppressed. As a result, the occurrence of an internal short circuit due to the outflow of the negative electrode 3 toward the positive electrode 2 and the accompanying heat generation of the battery can be prevented.

Hereinafter, the details of the alkaline battery will be described.
(Negative electrode)
Examples of the negative electrode active material include zinc and zinc alloys. The zinc alloy may contain at least one selected from the group consisting of indium, bismuth and aluminum from the viewpoint of corrosion resistance. The indium content in the zinc alloy is, for example, 0.01 to 0.1% by mass, and the bismuth content is, for example, 0.003 to 0.02% by mass. The aluminum content in the zinc alloy is, for example, 0.001 to 0.03% by mass. The proportion of elements other than zinc in the zinc alloy is preferably 0.025 to 0.08 mass% from the viewpoint of corrosion resistance.

  The negative electrode active material is usually used in a powder form. From the viewpoint of the filling property of the negative electrode and the diffusibility of the alkaline electrolyte in the negative electrode, the average particle diameter (D50) of the negative electrode active material powder is, for example, 100 to 200 μm, preferably 110 to 160 μm. In the present specification, the average particle diameter (D50) is a median diameter in a volume-based particle size distribution. The average particle diameter can be obtained, for example, using a laser diffraction / scattering particle distribution measuring apparatus.

  The negative electrode is obtained, for example, by mixing negative electrode active material particles containing zinc, terephthalic acid particles, a gelling agent, and an alkaline electrolyte. The average particle diameter (D50) of the terephthalic acid powder added to the negative electrode is preferably 50 to 300 μm. In this case, it is possible to further suppress the outflow of the negative electrode to the positive electrode side due to the buckling of the separator due to the flow of the negative electrode due to the impact or vibration applied to the battery when the battery is dropped or transported.

As the gelling agent, a known gelling agent used in the field of alkaline dry batteries is used without particular limitation, and for example, a water-absorbing polymer can be used. Examples of such a gelling agent include polyacrylic acid and sodium polyacrylate.
The addition amount of the gelling agent is, for example, 0.5 to 2 parts by mass per 100 parts by mass of the negative electrode active material.

  A surfactant such as a polyoxyalkylene group-containing compound or a phosphate ester may be used for the negative electrode in order to adjust the viscosity. Among these, phosphate esters or alkali metal salts thereof are preferable. From the viewpoint of more uniformly dispersing the surfactant in the negative electrode, the surfactant is preferably added in advance to the alkaline electrolyte used in preparing the negative electrode.

  In order to improve corrosion resistance, a compound containing a metal having a high hydrogen overvoltage such as indium or bismuth may be added to the negative electrode as appropriate. In order to suppress the growth of dendrites such as zinc, a slight amount of silicic acid compound such as silicic acid or a potassium salt thereof may be appropriately added to the negative electrode.

(Negative electrode current collector)
Examples of the material of the negative electrode current collector inserted into the gelled negative electrode include metals and alloys. The negative electrode current collector preferably contains copper, and may be made of an alloy containing copper and zinc such as brass, for example. The negative electrode current collector may be subjected to a plating treatment such as tin plating, if necessary.

(Positive electrode)
The positive electrode usually contains a conductive agent and an alkaline electrolyte in addition to manganese dioxide, which is a positive electrode active material. Moreover, the positive electrode may further contain a binder as necessary.
As manganese dioxide, electrolytic manganese dioxide is preferable. Examples of the crystal structure of manganese dioxide include α-type, β-type, γ-type, δ-type, ε-type, η-type, λ-type, and ramsdellite-type.

  Manganese dioxide is used in powder form. From the viewpoint of easily ensuring the filling property of the positive electrode and the diffusibility of the electrolytic solution in the positive electrode, the average particle diameter (D50) of manganese dioxide is, for example, 25 to 60 μm.

From the viewpoint of moldability and suppression of expansion of the positive electrode, the BET specific surface area of manganese dioxide may be, for example, in the range of 20 to 50 m ² / g. The BET specific surface area is obtained by measuring and calculating the surface area using the BET formula, which is a theoretical formula for multimolecular layer adsorption. The BET specific surface area can be measured, for example, by using a specific surface area measuring apparatus by a nitrogen adsorption method.

  Examples of the conductive agent include carbon black such as acetylene black and conductive carbon materials such as graphite. As graphite, natural graphite, artificial graphite and the like can be used. The conductive agent may be fibrous or the like, but is preferably powdery. The average particle diameter (D50) of the conductive agent is, for example, 3 to 20 μm.

  Content of the electrically conductive agent in a positive electrode is 3-10 mass parts with respect to 100 mass parts of manganese dioxide, Preferably it is 5-9 mass parts.

The positive electrode is obtained, for example, by pressure-molding a positive electrode active material, a conductive agent, an alkaline electrolyte, and a positive electrode mixture containing a binder as necessary into a pellet form. The positive electrode mixture may be once formed into flakes or granules, classified as necessary, and then pressed into pellets.
After the pellets are accommodated in the battery case, the pellets are secondarily pressed using a predetermined instrument so as to be in close contact with the inner wall of the battery case.

(Separator)
Examples of the material of the separator include cellulose and polyvinyl alcohol. The separator may be a non-woven fabric mainly composed of the fibers of the above materials, or may be a microporous membrane such as cellophane or polyolefin. You may use a nonwoven fabric and a microporous film together.
As a separator, it is preferable to use a nonwoven fabric. As such a nonwoven fabric, a nonwoven fabric mainly composed of cellulose fibers and polyvinyl alcohol fibers can be exemplified. Examples of the cellulose fiber include rayon fiber (regenerated fiber). Content of the polyvinyl alcohol fiber in a nonwoven fabric is 25-150 mass parts per 100 mass parts of cellulose fibers, for example.

  In FIG. 1, a cylindrical separator 4 with a bottom is configured by using a cylindrical separator 4a and a bottom paper 4b. The bottomed cylindrical separator is not limited to this, and a known separator used in the field of alkaline batteries may be used. The separator may be constituted by a single sheet, or may be constituted by overlapping a plurality of sheets if the sheet constituting the separator is thin. The cylindrical separator may be configured by winding a thin sheet a plurality of times.

(Alkaline electrolyte)
The alkaline electrolyte is contained in the positive electrode, the negative electrode, and the separator. As the alkaline electrolyte, for example, an alkaline aqueous solution containing potassium hydroxide is used. The concentration of potassium hydroxide in the alkaline electrolyte is preferably 30 to 50% by mass. The alkaline aqueous solution may further contain zinc oxide. The concentration of zinc oxide in the alkaline electrolyte is, for example, 1 to 5% by mass.

(Battery case)
For example, a bottomed cylindrical metal case is used as the battery case. For example, a nickel-plated steel plate is used for the metal case. In order to improve the adhesion between the positive electrode and the battery case, it is preferable to use a battery case in which the inner surface of the metal case is covered with a carbon film.

  EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example and a comparative example, this invention is not limited to a following example.

<< Examples 1-4 >>
According to the following procedures (1) to (3), an AA cylindrical alkaline dry battery (LR6) shown in FIG. 1 was produced.
(1) Production of Positive Electrode Graphite powder (average particle size (D50) 8 μm) as a conductive agent was added to electrolytic manganese dioxide powder (average particle size (D50) 35 μm) as a positive electrode active material to obtain a mixture. The mass ratio of the electrolytic manganese dioxide powder and the graphite powder was 92.4: 7.6. The electrolytic manganese dioxide powder used had a specific surface area of 41 m ² / g. An electrolyte solution was added to the mixture, and after sufficiently stirring, the mixture was compression molded into flakes to obtain a positive electrode mixture. The mass ratio of the mixture and the electrolyte was 100: 1.5. An alkaline aqueous solution containing potassium hydroxide (concentration 35 mass%) and zinc oxide (concentration 2 mass%) was used as the electrolytic solution.

  The flaky positive electrode mixture was pulverized into granules and classified by a sieve. 11 g of granules of 10 to 100 mesh were pressure-formed into a predetermined hollow cylindrical shape having an outer diameter of 13.65 mm to produce two positive electrode pellets.

(2) Production of negative electrode Zinc alloy powder (average particle diameter (D50) 130 μm), terephthalic acid powder (average particle diameter (D50) 150 μm), negative electrode active material, the above electrolyte, and a gelling agent The gelled negative electrode 3 was obtained by mixing. As the zinc alloy, a zinc alloy containing 0.02 mass% indium, 0.01 mass% bismuth, and 0.005 mass% aluminum was used. As the gelling agent, a mixture of crosslinked branched polyacrylic acid and highly crosslinked chain-type sodium polyacrylate was used. The mass ratio of the negative electrode active material, the electrolytic solution, and the gelling agent was 100: 50: 1. The terephthalic acid was used in an amount (parts by mass) shown in Table 1 per 100 parts by mass of the negative electrode active material.

(3) Assembling the alkaline battery Nihon Graphite Co., Ltd. on the inner surface of a nickel-plated steel bottomed cylindrical battery case (outer diameter 13.80 mm, cylindrical wall thickness 0.15 mm, height 50.3 mm) The bunny height manufactured was applied to form a carbon film having a thickness of about 10 μm, and a battery case 1 was obtained. Two positive electrode pellets were inserted vertically into the battery case 1 and then pressed to form the positive electrode 2 in close contact with the inner wall of the battery case 1. After placing the bottomed cylindrical separator 4 inside the positive electrode 2, the electrolyte solution was injected and impregnated in the separator 4. In this state, the electrolyte solution was allowed to permeate from the separator 4 to the positive electrode 2 by being left for a predetermined time. Thereafter, 6 g of the gelled negative electrode 3 was filled inside the separator 4.

The separator 4 was configured using a cylindrical separator 4a and a bottom paper 4b. As the cylindrical separator 4a and the bottom paper 4b, a non-woven sheet (basis weight 28 g / m ² ) mainly composed of rayon fibers and polyvinyl alcohol fibers having a mass ratio of 1: 1 was used. The thickness of the nonwoven fabric sheet used for the bottom paper 4b was 0.27 mm.

  The separator 4a (thickness before swelling: 300 μm) was formed by wrapping a nonwoven fabric sheet having a thickness of 100 μm in triplicate. At this time, a portion P1 where one end portion of the nonwoven fabric sheet at the beginning of winding and the other end portion of the nonwoven fabric sheet at the end of winding overlap each other was provided. In the cross section perpendicular to the axial direction (X direction in FIG. 1) of the positive electrode of the separator, the length L1 of the overlapping portion P1 was 3 mm.

  The negative electrode current collector 6 was obtained by pressing a general brass (Cu content: about 65% by mass, Zn content: about 35% by mass) into a nail mold and then performing tin plating on the surface. . The diameter of the body part of the negative electrode current collector 6 was 1.15 mm. The head of the negative electrode current collector 6 was electrically welded to a negative electrode terminal plate 7 made of a nickel-plated steel plate. Thereafter, the body of the negative electrode current collector 6 was press-fitted into the through hole at the center of the gasket 5 containing polyamide 6 and 12 as a main component. In this manner, a sealing unit 9 including the gasket 5, the negative electrode terminal plate 7, and the negative electrode current collector 6 was produced.

  Next, the sealing unit 9 was installed in the opening of the battery case 1. At this time, the body of the negative electrode current collector 6 was inserted into the negative electrode 3. The opening end of the battery case 1 was caulked to the peripheral edge of the negative electrode terminal plate 7 via the gasket 5 to seal the opening of the battery case 1. The outer surface of the battery case 1 was covered with the exterior label 8. In this manner, an alkaline battery was produced.

<< Comparative Example 1 >>
In the production of the negative electrode, an alkaline dry battery was produced in the same manner as in Example 1 except that terephthalic acid was not used.

<< Comparative Example 2 >>
In the production of the negative electrode, an alkaline dry battery was produced in the same manner as in Example 1 except that the content of terephthalic acid (amount per 100 parts by mass of the negative electrode active material) was changed to the values shown in Table 1.

[Evaluation]
The following evaluation was performed using the obtained alkaline dry battery.
(I) Evaluation of safety Ten batteries of Examples and Comparative Examples were prepared. Ten batteries were dropped onto a plastic tile from a height of 100 cm with the negative electrode side (negative electrode terminal plate 7 side in FIG. 1) facing downward. At this time, the number of batteries that generated heat at 40 ° C or higher was determined.

(Ii) Measurement of the thickness of the separator (after swelling) A cross section image (cross section perpendicular to the X direction in FIG. 1) of 20 mm in the axial direction of the battery (X direction in FIG. 1) from the positive electrode terminal surface is a CT scan. The distance between the positive electrode and the negative electrode (the length in the radial direction) was measured as the thickness of the separator 4a (swelled state including the electrolytic solution). Arbitrary one point (excluding the part where one end of the winding start and the other end of the winding overlap each other) where the cylindrical separator 4a is disposed between the positive electrode and the negative electrode is determined. Measured points when rotated 90 degrees around the battery axis (the remaining three points excluding the portion where one end of winding and the other end of winding overlap each other) The same measurement was performed for. Of the four measured values, the average value of the remaining two measured values excluding the maximum and minimum values was determined.

(Iii) Measurement of average particle size of terephthalic acid particles in negative electrode After disassembling the battery and taking out the gelled negative electrode, the negative electrode active material is removed from the negative electrode by centrifugation, and the gelling agent and terephthalic acid A mixture of particles was obtained. The obtained mixture was dried and then observed using an optical microscope, and 10 particles of terephthalic acid were randomly selected. Then, the particle size of each particle is measured, two measured values are deleted in order from the largest measured value, and the two measured values are deleted in order from the smallest measured value, and the average value of the remaining six measured values is determined as terephthalic acid in the negative electrode. The average particle size of the particles was determined.
The evaluation results are shown in Table 1.

  The thicknesses of the separators of Examples 1 to 4 and Comparative Examples 1 and 2 (after swelling) were about 390 μm. The average particle diameter of the terephthalic acid particles in the negative electrodes of Examples 1 to 4 and Comparative Example 2 was about 150 μm.

  In Examples 1 to 4 in which the content of terephthalic acid is 0.05 to 1.0 part by mass per 100 parts by mass of the negative electrode active material and the thickness of the separator (after swelling) is about 390 μm, heated batteries are observed. There wasn't. In Comparative Example 1 in which terephthalic acid was not added to the negative electrode, there was a battery that generated heat. In Comparative Example 2 where the content of terephthalic acid is 0.01 parts by mass per 100 parts by mass of the negative electrode active material and the thickness of the separator (after swelling) is about 390 μm, the effect of adding terephthalic acid is insufficient. There was a battery that generated heat.

  When the separator 4a (thickness before swelling: 330 μm) was formed by wrapping a nonwoven fabric sheet having a thickness of 110 μm in triplicate, the thickness of the separator after swelling was about 420 μm. In this case, since the thickness of the separator became too large and the filling amount of the negative electrode into the hollow part of the positive electrode decreased, the negative electrode capacity could not be ensured.

  Further, when the amount of terephthalic acid added to the negative electrode was 2 parts by mass per 100 parts by mass of the negative electrode active material, the viscosity of the negative electrode increased, making it difficult to fill the hollow part of the positive electrode.

<< Examples 5 to 8 >>
In the production of the negative electrode, the content of terephthalic acid (the amount per 100 parts by mass of the negative electrode active material) was set to the values shown in Table 1. Separator 4a (thickness 230 μm before swelling) was constituted by wrapping a nonwoven fabric sheet having a thickness of 115 μm twice. Except for the above, an alkaline dry battery was prepared and evaluated in the same manner as in Example 1.

<< Comparative Example 3 >>
In the production of the negative electrode, an alkaline dry battery was produced and evaluated in the same manner as in Example 5 except that terephthalic acid was not used.

<< Comparative Example 4 >>
In producing the negative electrode, an alkaline dry battery was produced and evaluated in the same manner as in Example 5 except that the content of terephthalic acid (amount per 100 parts by mass of the negative electrode active material) was changed to the values shown in Table 1.
The evaluation results are shown in Table 2.

  The thicknesses of the separators (after swelling) in Examples 5 to 8 and Comparative Examples 3 to 4 were about 300 μm. The average particle diameter of the terephthalic acid particles in the negative electrodes of Examples 5 to 8 and Comparative Example 4 was about 150 μm.

  In Examples 5 to 8 in which the content of terephthalic acid is 0.05 to 1.0 part by mass per 100 parts by mass of the negative electrode active material and the thickness of the separator (after swelling) is about 300 μm, heated batteries are observed. There wasn't. In Comparative Example 3 in which terephthalic acid was not added to the negative electrode, there was a battery that generated heat. In Comparative Example 4 where the content of terephthalic acid is 0.01 parts by mass per 100 parts by mass of the negative electrode active material and the thickness of the separator (after swelling) is about 300 μm, the effect of adding terephthalic acid is insufficient. There was a battery that generated heat.

<< Examples 9 to 12 >>
In the production of the negative electrode, the content of terephthalic acid (the amount per 100 parts by mass of the negative electrode active material) was set to the values shown in Table 1. Separator 4a (thickness before swelling: 200 μm) was constituted by wrapping a 100 μm thick non-woven sheet twice. Except for the above, an alkaline dry battery was prepared and evaluated in the same manner as in Example 1.

<< Comparative Example 5 >>
In the production of the negative electrode, an alkaline dry battery was produced and evaluated in the same manner as in Example 9 except that terephthalic acid was not used.

<< Comparative Example 6 >>
In the production of the negative electrode, an alkaline dry battery was produced and evaluated in the same manner as in Example 9 except that the content of terephthalic acid (amount per 100 parts by mass of the negative electrode active material) was set to the values shown in Table 1.

<< Comparative Example 7 >>
In the production of the negative electrode, the same procedure as in Example 9 was conducted except that 2 parts by mass of vinylon fiber (length: about 4 mm, thickness: 0.5 to 1 denier) was added per 100 parts by mass of the negative electrode active material instead of terephthalic acid. An alkaline battery was prepared and evaluated.

<< Comparative Example 8 >>
In the production of the negative electrode, the same procedure as in Example 9 was conducted except that 2 parts by mass of rayon fiber (length of about 4 mm, thickness of 0.5 to 1 denier) was added per 100 parts by mass of the negative electrode active material instead of terephthalic acid. An alkaline battery was prepared and evaluated.
The evaluation results are shown in Table 3.

  The thicknesses of the separators (after swelling) in Examples 9 to 12 and Comparative Examples 5 to 8 were about 260 μm. The average particle diameter of the terephthalic acid particles in the negative electrodes of Examples 9 to 12 and Comparative Example 6 was about 150 μm.

  In Examples 9 to 12 in which the content of terephthalic acid was 0.05 to 1.0 part by mass per 100 parts by mass of the negative electrode active material and the thickness of the separator (after swelling) was about 260 μm, a battery that generated heat was observed. There wasn't.

  In Comparative Example 5 in which terephthalic acid was not added to the negative electrode, there was a battery that generated heat. In Comparative Example 6 in which the content of terephthalic acid is 0.01 parts by mass per 100 parts by mass of the negative electrode active material and the thickness of the separator (after swelling) is about 260 μm, the effect of adding terephthalic acid is insufficient. There was a battery that generated heat. In Comparative Examples 7 and 8 to which fibers were added, there was a battery that generated heat.

<< Examples 13 to 16 >>
In the production of the negative electrode, the content of terephthalic acid (amount per 100 parts by mass of the negative electrode active material) was set to the values shown in Table 4. The separator 4a (thickness before swelling: 170 μm) was constituted by wrapping a non-woven sheet having a thickness of 85 μm twice.
Except for the above, an alkaline dry battery was prepared and evaluated in the same manner as in Example 1.

<< Comparative Example 9 >>
In the production of the negative electrode, an alkaline dry battery was produced and evaluated in the same manner as in Example 13 except that terephthalic acid was not used.

<< Comparative Example 10 >>
In the production of the negative electrode, an alkaline dry battery was produced and evaluated in the same manner as in Example 13 except that the content of terephthalic acid (amount per 100 parts by mass of the negative electrode active material) was set to the values shown in Table 1.

<< Comparative Example 11 >>
In the production of the negative electrode, the same procedure as in Example 13 was conducted except that 2 parts by mass of vinylon fiber (length: about 4 mm, thickness: 0.5 to 1 denier) was added per 100 parts by mass of the negative electrode active material instead of terephthalic acid. An alkaline battery was prepared and evaluated.

<< Comparative Example 12 >>
In the production of the negative electrode, the same procedure as in Example 13 was conducted except that 2 parts by mass of rayon fiber (length of about 4 mm, thickness of 0.5 to 1 denier) was added per 100 parts by mass of the negative electrode active material instead of terephthalic acid. An alkaline battery was prepared and evaluated.
The evaluation results are shown in Table 4.

  The thicknesses of the separators (after swelling) in Examples 13 to 16 and Comparative Examples 9 to 12 were about 220 μm. The average particle diameter of the terephthalic acid particles in the negative electrodes of Examples 13 to 16 and Comparative Example 10 was about 150 μm.

  In Examples 13 to 16 in which the content of terephthalic acid is 0.05 to 1.0 part by mass per 100 parts by mass of the negative electrode active material and the thickness of the separator (after swelling) is about 220 μm, a battery that generates heat is seen. There wasn't.

  In Comparative Example 5 in which terephthalic acid was not added to the negative electrode, there was a battery that generated heat. In Comparative Example 10 in which the content of terephthalic acid is 0.01 parts by mass per 100 parts by mass of the negative electrode active material and the thickness of the separator (after swelling) is about 220 μm, the effect of adding terephthalic acid is insufficient. There was a battery that generated heat. In Comparative Examples 11 and 12 to which fibers were added, there was a battery that generated heat.

<< Comparative Examples 13-18 >>
In the production of the negative electrode, the content of terephthalic acid (amount per 100 parts by mass of the negative electrode active material) was set to the values shown in Table 4. Separator 4a (thickness 150 μm before swelling) was constituted by double-wrapping a 75 μm thick nonwoven sheet. Except for the above, an alkaline dry battery was prepared and evaluated in the same manner as in Example 1.
The evaluation results are shown in Table 5.

  The thickness of the separators (after swelling) of Comparative Examples 13 to 18 was about 200 μm. The average particle diameter of the terephthalic acid particles in the negative electrodes of Comparative Examples 13 to 18 was about 150 μm.

In Comparative Example 13 in which no terephthalic acid was added to the negative electrode, the effect of adding terephthalic acid could not be obtained, and the separator (after swelling) was thin, so there was a battery that generated heat. In Comparative Example 14 in which the content of terephthalic acid is 0.01 parts by mass per 100 parts by mass of the negative electrode active material and the thickness of the separator (after swelling) is about 200 μm, the effect due to the addition of terephthalic acid is insufficient. Since the thickness of the separator (after swelling) was thin, there was a battery that generated heat.
In Comparative Examples 15 to 18 in which the content of terephthalic acid is 0.05 to 1.0 part by mass per 100 parts by mass of the negative electrode active material and the thickness of the separator (after swelling) is about 200 μm, the separator (after swelling) There was a battery that generated heat due to its thin thickness.

<< Examples 17 to 20 >>
An alkaline dry battery was prepared and evaluated in the same manner as in Example 1 except that the average particle diameter of terephthalic acid in the negative electrode was changed to the value shown in Table 6.

Furthermore, the following evaluation was performed about the battery of Example 1 and 17-20.
(Iv) Evaluation of reliability Ten batteries of the examples were prepared. Each battery was dropped onto a plastic tile from a height of 100 cm with the negative electrode side facing down. At this time, the number of batteries whose battery voltage was lowered in the range of 5 mV or less was obtained.
The evaluation results are shown in Table 6.

  The thicknesses of the separators of Example 1 and 17-20 (after swelling) were about 260 μm. The average particle diameters of the terephthalic acid particles in the negative electrodes of Examples 17, 18, 1, 19, and 20 were about 30 μm, about 50 μm, about 150 μm, about 300 μm, and about 500 μm, respectively.

  In any of the examples, no exothermic battery was observed. In Examples 1, 18, and 19 in which the average particle diameter of the terephthalic acid particles in the negative electrode is about 50 to 300 μm, the negative electrode has excellent filling properties in the hollow portion of the positive electrode, and the battery is in a range of 5 mV or less. No batteries with reduced voltage were found.

  In Example 17 in which the average particle size of the terephthalic acid particles in the negative electrode was about 30 μm, no battery with a reduced battery voltage was found in the range of 5 mV or less, but the negative electrode was able to be filled into the hollow part of the positive electrode. Slightly decreased. In Example 20 in which the average particle diameter of the terephthalic acid particles in the negative electrode was about 500 μm, the filling of the negative electrode into the hollow part of the positive electrode was excellent, but there was a battery in which the battery voltage decreased in the range of 5 mV or less. It was.

<< Examples 21 to 24 >>
Example 1 except that the length L1 of the portion P1 where one end of the winding and the other end of the winding overlap each other is changed to the value shown in Table 7 in the configuration of the cylindrical separator. In the same manner, an alkaline battery was prepared and evaluated. Furthermore, the reliability of (iv) was also evaluated.

  The thicknesses of the separators (after swelling) of Examples 1 and 21 to 24 were about 260 μm. The average particle diameter of the terephthalic acid particles in the negative electrodes of Examples 1 and 21 to 24 was about 150 μm.

  In any of the examples, no exothermic battery was observed. In Examples 1, 22, and 23 in which the length L1 of the overlapping portion P1 was 0 to 6 mm, no battery in which the battery voltage was lowered in the range of 5 mV or less was found.

  In Example 21 in which the length L1 of the overlapping portion P1 was −3 mm, there was a battery in which the battery voltage was reduced within a range of 5 mV or less. This is presumably because, in Example 21, there was a portion where the thickness of the separator was reduced, and the strength was reduced at that portion. Note that the length L1 of the overlapping portion P1 is −3 mm means that one end at the beginning of winding and the other end at the end of winding are separated by 3 mm, and the thickness of the separator is at that portion. It means that it is getting thinner.

  In Example 24, in which the length L1 of the overlapping portion P1 was 9 mm, there was a battery in which the battery voltage was lowered in the range of 5 mV or less. This is because in Example 22, the thickness of the separator is increased in the overlapping portion P1, and the difference in the thickness of the separator is increased between the overlapping portion P1 and the portion other than the portion P1, thereby making the separator slightly buckled. It is thought that.

  According to one embodiment of the present invention, it can be used for any device that uses a dry cell as a power source. For example, it is suitable for portable audio equipment, electronic games, lights, toys and the like.

  1: battery case, 2: positive electrode, 3: negative electrode, 4: bottomed cylindrical separator, 4a: cylindrical separator, 4b: bottom paper, 5: gasket, 6: negative electrode current collector, 7: negative electrode terminal plate 8: exterior label, 9: sealing unit, 14a: sheet, 24: separator, 24a, 24b: sheet, 34: separator, 34a, 34b: sheet

Claims (4)

Included in a hollow cylindrical positive electrode, a gelled negative electrode disposed in a hollow portion of the positive electrode, a separator disposed between the positive electrode and the negative electrode, the positive electrode, the negative electrode, and the separator With alkaline electrolyte,
The negative electrode includes a negative electrode active material containing zinc and terephthalic acid,
The content of the terephthalic acid in the negative electrode is 0.05 to 1 part by mass per 100 parts by mass of the negative electrode active material,
The alkaline battery is a separator having a thickness of 220 to 390 μm.   2. The alkaline dry battery according to claim 1, wherein the terephthalic acid particles have an average particle diameter of 50 to 300 μm. The separator includes a sheet wound along the inner surface of the hollow portion of the positive electrode,
The separator has a portion where one end of the winding start of the sheet and the other end of the winding end of the sheet overlap each other,
The alkaline dry battery according to claim 1 or 2, wherein a length of the overlapping portion is 6 mm or less in a cross section perpendicular to the axial direction of the positive electrode of the separator. The separator includes a plurality of sheets sequentially arranged along the inner surface of the hollow portion of the positive electrode,
The separator has a portion where ends of the adjacent sheets overlap each other.
The alkaline dry battery according to claim 1 or 2, wherein a length of the overlapping portion is 6 mm or less in a cross section perpendicular to the axial direction of the positive electrode of the separator.

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