JP2010153287A - Alkaline battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an alkaline battery capable of suppressing gas evolution on the inside in non-discharge and overdischarge. <P>SOLUTION: A cylindrical alkaline battery includes a gelled negative electrode containing zinc alloy powder, an electrolyte of an alkali aqueous solution, and a negative current collector rod in which at least one end is immersed in the gelled negative electrode and the other end is electrically connected to a negative terminal plate, the zinc powder contains 50-125 ppm of Bi, 100-2,000 ppm of Al, and 1-50 ppm in total of at least one of Ca and Mg, the negative current collector rod is made of brass and has an Sn plating layer having a thickness of 0.6 μm or more on the surface. Preferably, the Sn plating layer of the negative current collector rod is formed by an electrolytic plating method. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to an alkaline battery with a small amount of gas generation in the battery during undischarged and overdischarged.

  In a cylindrical alkaline battery using a negative electrode agent containing zinc or a zinc alloy in the negative electrode, the electrical connection between the negative electrode terminal plate and the negative electrode constituting the battery outer body, together with the outer can (positive electrode can), This is performed by immersing a negative electrode current collector rod, the head of which is welded to the negative electrode terminal plate, in the negative electrode agent.

  The negative electrode current collector rod is generally made of brass, but in an alkaline battery before use (an undischarged alkaline battery), the brass constituting the negative electrode current collector rod is the cause. There is a problem that gas is generated in the alkaline battery and the electrolyte solution leaks out. For this reason, a technology was developed to avoid the gas generation problem described above by plating the surface of the negative electrode current collector rod made of brass with zinc, tin, lead, etc., and increasing the hydrogen overvoltage on the surface of the negative electrode current collector rod. (For example, Patent Document 1).

  Moreover, in recent years, leakage of electrolyte due to gas generation during overdischarge has been regarded as a problem in alkaline batteries having a negative electrode current collector rod made of brass as described above. For example, there is no problem if the discharged alkaline battery is taken out from the equipment used relatively early. However, if the alkaline battery is left in the equipment for a long time after the discharge is finished, the alkaline battery becomes overdischarged. In this case, gas is generated inside and liquid leakage occurs.

  Patent Document 2 points out that the reason why gas is generated inside the alkaline battery during overdischarge is that tin (Sn) plating on the surface of the negative electrode current collector rod elutes into the electrolyte. In addition to optimizing the configuration, the tin plating is thinned to reduce the amount of tin in the battery that causes gas generation during overdischarge as much as possible, thereby suppressing gas generation during overdischarge.

Japanese Patent Laid-Open No. 5-13085 JP 2006-172908 A

  However, as described above, if the gas generation at the time of overdischarge is suppressed by reducing the plating thickness on the surface of the negative electrode current collector rod, the effect of suppressing the gas generation at the time of non-discharge due to plating is impaired.

  This invention is made | formed in view of the said situation, The objective is to provide the alkaline battery which can suppress the gas generation inside at the time of an undischarge and an overdischarge.

  The alkaline battery (alkali primary battery) of the present invention that has achieved the above object has a gelled negative electrode containing zinc alloy powder and an electrolytic solution composed of an alkaline aqueous solution, and at least one end thereof is the gelled negative electrode. A cylindrical alkaline battery having a negative electrode current collecting rod immersed in the other end and electrically connected to the negative electrode terminal plate, wherein the zinc alloy has Bi of 50 to 125 ppm and Al of 100 to 2000 ppm. In addition, the negative electrode current collector rod is made of brass and has a Sn plating layer having a thickness of 0.6 μm or more on the surface. is there. In addition, content of each element in the zinc alloy which concerns on the zinc alloy powder as used in this specification is a mass reference | standard.

  In the alkaline battery of the present invention, unlike the battery according to Patent Document 2, for example, the Sn plating related to the negative electrode current collector rod is thickened as described above so that the battery related to the negative electrode current collector bar is undischarged due to the brass. It is possible to suppress the gas generation inside.

  Further, in the present invention, the negative electrode zinc alloy powder is made of a zinc alloy having the specific composition described above, so that the Sn plating related to the negative electrode current collector rod is thickened at the time of overdischarge. It suppresses gas generation and gas generation during overdischarge caused by the Zn component related to the negative electrode.

  ADVANTAGE OF THE INVENTION According to this invention, the alkaline battery which can suppress internal gas generation | occurrence | production at the time of undischarge and overdischarge can be provided.

  FIG. 1 shows a cross-sectional view of an example of the alkaline battery of the present invention. In the alkaline battery of FIG. 1, a positive electrode 2 (positive electrode mixture molded body) formed in a ring shape is disposed in a cylindrical (cylindrical or rectangular) outer can 1, and a cup shape is disposed on the inside thereof. The separator 3 is arranged, and an alkaline electrolyte (not shown) is injected from the inside of the separator 3. Further, the inside of the separator 3 is filled with a negative electrode 4 (negative electrode mixture). 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 bent inward and sealed. The negative electrode current collector rod 5 is welded to the negative electrode terminal plate 7 at its head, and the negative electrode current collector rod 5 is inserted into the negative electrode 4 through the through hole 64 provided in the central portion 61 of the sealing body 6. Yes. Further, a metal washer 9 (disc-shaped metal plate) is disposed as a supporting means for preventing the negative electrode terminal plate 7 from being deformed during sealing and supporting the sealing body 6 from the inside.

  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 metal washer 9 side from the generated fissure. The metal washer 9 and the negative electrode terminal plate 7 are provided with gas vent holes (not shown), and the gas in the battery is discharged out of the battery through these gas vent holes.

  FIG. 2 shows a cross-sectional view of another example of the alkaline battery of the present invention. In FIG. 2, elements having the same functions as those in FIG. In FIG. 2, 8 is an insulating plate for insulating the outer can 1 and the negative electrode terminal plate 7, and 20 is a body portion that houses the power generation element.

  In the alkaline battery shown in FIG. 1, since the metal washer 9 is used, the volume occupied by the sealing portion (10 in FIG. 1) becomes large. On the other hand, by eliminating the metal washer as in the battery of FIG. 2 and using the negative electrode terminal plate 7 as a support means for supporting the sealing body 6 from the inside, the volume occupied by the sealing portion 10 can be reduced and the power generation element can be reduced. The volume of the trunk portion 20 that can be accommodated can be increased, and the filling amount of each mixture of the positive electrode 2 and the negative electrode 4 can be increased as compared with the battery of FIG.

  Hereinafter, the alkaline battery of the present invention will be described in detail.

<Negative electrode current collector rod>
The negative electrode current collector rod according to the battery of the present invention is made of brass and has a Sn plating layer on the surface thereof. The Sn plating layer can suppress gas generation in the battery when not discharged due to brass.

  The Sn plating layer may be composed only of Sn, but may contain other elements (Pb, In, Bi, Al, Mg, Ca, etc.) as long as the effects of the present invention are not impaired.

  The thickness of the Sn plating layer is 0.6 μm or more and preferably 0.8 μm or more from the viewpoint of suppressing gas generation in the battery when not discharged due to brass. In addition, from the viewpoint of further suppressing the amount of gas generated during overdischarge, the thickness of the Sn plating layer is preferably 10 μm or less, and more preferably 5 μm or less.

  The Sn plating layer related to the negative electrode current collector rod is preferably formed by an electrolytic plating method. This is because the electrolytic plating method makes it easier to control the thickness of the plating layer to be formed, and a thicker plating layer can be easily formed as compared with the electroless plating method.

<Negative electrode>
For the negative electrode according to the alkaline battery of the present invention, a gelled negative electrode mixture (gelled negative electrode) having a zinc alloy powder, an electrolytic solution, and a gelling agent is used. A Zn (zinc) component in the zinc alloy powder acts as a negative electrode active material.

  The zinc alloy powder is composed of zinc alloys containing, as alloy elements, Bi of 50 ppm to 125 ppm, Al of 100 ppm to 2000 ppm, and at least one of Ca and Mg of 1 ppm to 50 ppm. In the alkaline battery of the present invention, the use of a zinc alloy powder having the above composition for the negative electrode suppresses gas generation inside during overdischarge. In addition, gas generation inside when not discharged can also be suppressed by using a zinc alloy powder having the above composition for the negative electrode.

  In an alkaline battery using a zinc alloy powder as a negative electrode, gas is generated due to corrosion of Zn related to the zinc alloy powder in addition to gas generation due to brass constituting the negative electrode current collector rod when not discharged. With regard to such gas generation due to corrosion of Zn, in a conventional alkaline battery, for example, by adding Bi or the like as an alloy element to a zinc alloy used for a negative electrode, Zn of the zinc alloy powder in an undischarged state can be obtained. Corrosion was suppressed and gas generation was suppressed.

  However, in such an alkaline battery, when an overdischarge state occurs after the end of discharge, gas generation is promoted in the zinc alloy powder by the reaction of the remaining Zn component and Bi without participating in the discharge reaction. However, it became clear by examination of the present inventors. In addition, when the Sn plating layer formed on the surface of the brass constituting the negative electrode current collector rod is thick like the battery of the present invention, the Sn is eluted and remains when the battery is overdischarged. Gas generation also occurs by reacting with the Zn component.

  Therefore, in the present invention, the amount of Bi in the zinc alloy related to the zinc alloy powder is limited to suppress gas generation at the time of overdischarge resulting from Sn elution from the Zn component related to the negative electrode and the negative electrode current collector rod. Further, by containing Al, Ca and / or Mg in a specific amount as an alloy component of the zinc alloy, gas generation at the time of overdischarge due to Zn elution related to the negative electrode and Sn elution from the negative electrode current collector rod can be achieved. In addition, it is possible to compensate for the suppression effect of gas generation at the time of non-discharge, which may be reduced by limiting the amount of Bi, and to satisfactorily suppress gas generation due to the Zn component even at the time of non-discharge. I made it.

  The Bi content in the zinc alloy related to the zinc alloy powder is 125 ppm or less and preferably 100 ppm or less from the viewpoint of suppressing gas generation during overdischarge. However, if the amount of Bi in the zinc alloy is too small, there is a possibility that the gas generation suppression action at the time of non-discharge will be too small, so the Bi content in the zinc alloy according to the zinc alloy powder is 50 ppm or more, It is preferable that it is 75 ppm or more.

  By using Al as the alloy element of the zinc alloy related to the zinc alloy powder, it is presumed that the gas generation suppression during undischarged and overdischarge can be achieved for the following reason. When the zinc alloy related to the zinc alloy powder contains Al, the smoothness of the powder surface is improved. Therefore, it is considered that the corrosion reaction of the Zn component in the zinc alloy related to the zinc alloy powder at the time of unreacted hardly occurs and gas generation is suppressed. In addition, since the zinc alloy contains Al, Zn existing in the zinc oxide crystal generated by the discharge is partially substituted with Al having a single valence higher than Zn, Many conduction electrons can be generated. As a result, the conductivity of zinc oxide is increased, so that the utilization rate of Zn related to the zinc alloy powder can be improved, and the amount of unreacted Zn that causes gas generation during overdischarge can be reduced. It is considered that gas generation during discharge is suppressed.

  The Al content in the zinc alloy related to the zinc alloy powder is 100 ppm or more and 200 ppm or more from the viewpoint of securing the above-described effect (the effect of suppressing gas generation during undischarge and overdischarge) by containing Al. It is preferable that it is 500 ppm or more. However, if the amount of Al in the zinc alloy is too large, the effect is saturated and the production of the zinc alloy powder tends to be difficult. Therefore, the Al content in the zinc alloy related to the zinc alloy powder is 2000 ppm. Or less, preferably 1500 ppm or less, and more preferably 1200 ppm or less.

  Moreover, it is estimated that the gas generation suppression at the time of non-discharge and at the time of overdischarge can be achieved by including at least one of Ca and Mg in the zinc alloy related to the zinc alloy powder for the following reason. As described above, when the zinc alloy related to the zinc alloy powder contains Al, it is considered that the smoothness of the powder surface is improved and gas generation during undischarge can be suppressed. When Mg is contained, the smoothness of the powder surface is more likely to be improved, and it is presumed that the generation of gas during undischarge can be further suppressed. In addition, Ca and Mg can increase the conductivity of zinc oxide generated with discharge by the same mechanism as Al, so the utilization rate of Zn related to zinc alloy powder is improved and gas generation during overdischarge is suppressed. It is thought that it is done.

  The zinc alloy according to the zinc alloy powder may contain only one of Ca and Mg, or may contain both. The content of Ca and Mg in the zinc alloy related to the zinc alloy powder is the sum of both from the viewpoint of ensuring the above-described effect (the effect of suppressing gas generation during undischarged and overdischarged) due to the inclusion of these. In the case where only one of Ca and Mg is contained, the amount of one of them is the same, and the content of Ca and Mg is 1 ppm or more, and preferably 4 ppm or more. However, if the amount of Ca and Mg in the zinc alloy is too large, not only will the effect be saturated, but the discharge characteristics of the battery may deteriorate due to segregation of Ca or Mg. The total content of Ca and Mg in the alloy is 50 ppm or less, and preferably 20 ppm or less.

  The zinc alloy according to the zinc alloy powder typically contains other alloy elements as long as the portion other than the alloy elements is Zn and inevitable impurities, but does not impair the effects of the present invention. May be.

  Examples of alloy elements other than the alloy elements related to the zinc alloy include In. By containing In, the hydrogen overvoltage of the zinc alloy can be further increased, and the gas generation suppressing action when not discharged can be further improved. The content of In in the zinc alloy related to the zinc alloy powder is preferably 100 to 1000 ppm.

  Moreover, it is preferable that the zinc alloy in the zinc alloy which concerns on zinc alloy powder is 98 mass% or more.

  The proportion of the zinc alloy powder relating to the negative electrode that can pass through a 200 mesh sieve is preferably 10% by mass or more, and more preferably 20% by mass or more. When the zinc alloy powder has such a fine form, the specific surface area of the entire zinc alloy powder is increased, and the reaction at the negative electrode can be advanced efficiently, so that the load characteristics of the battery are improved. In addition, since the distance from the surface to the center of the zinc alloy powder is reduced, the utilization factor of Zn is improved even during discharge with a relatively small load (light load discharge). Therefore, at the end of discharge, the amount of unreacted Zn (Zn component amount in the zinc alloy powder) can be reduced to further suppress gas generation during overdischarge.

  The specific surface area of the entire zinc alloy powder increases as the proportion of the zinc alloy powder that can pass through the 200 mesh sieve increases, but this increases the reactivity between the zinc alloy powder and the electrolyte. In addition, the amount of gas generated from the zinc surface increases, and the generation of gas inside when not discharged increases. Moreover, when the ratio of the fine powder which occupies in a zinc alloy powder becomes large, the whole zinc alloy powder will become bulky and handling of the zinc alloy powder at the time of battery manufacture will become difficult. Therefore, in the battery of the present invention, from the viewpoint of suppressing internal gas generation when not discharged, and further improving the handleability of the zinc alloy powder at the time of battery production, it passes through a 200 mesh sieve in the zinc alloy powder. The ratio of what can be done is preferably 80% by mass or less, and more preferably 40% by mass or less.

  Furthermore, by using a zinc alloy powder that can pass through a 200 mesh sieve, the amount of gas generated due to corrosion due to reaction with the electrolyte during non-discharge is reduced. It is also possible to prepare a negative electrode mixture that is homogeneous and has good fluidity.

  In view of handling at the time of manufacturing the battery, it is desirable that the zinc alloy powder of the negative electrode has a minimum particle size of about 7 μm. Moreover, it is preferable that the zinc alloy powder, for example, as a whole can pass through 80 mesh screens.

  Furthermore, the negative electrode according to the present invention preferably contains an indium compound. As described above, in a battery using a zinc alloy powder composed of a zinc alloy having a high Al content for the negative electrode, for example, when discharged at a light load, a conductive reaction product (dendrite) is abnormally precipitated during the discharge. However, this causes an internal short circuit, and the discharge time of the battery, that is, the life of the battery may be shortened abnormally. In the present invention, as described above, by using a separator having a specific air permeability, the occurrence of the internal short circuit is suppressed, but by including an indium compound in the negative electrode, an ion exchange reaction of the indium compound is performed. As a result, In is segregated on the surface of the zinc alloy powder, and the occurrence of the internal short circuit can be further suppressed.

  This is presumed to be because In segregated on the surface of the zinc alloy powder suppresses the formation of dendrite from the zinc alloy powder. Moreover, the gas generation in the battery can be further suppressed by containing the indium compound in the negative electrode.

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

  The negative electrode according to the alkaline battery of the present invention is a gelled negative electrode and contains a gelling agent and an electrolytic solution in addition to the zinc alloy powder and the indium compound.

  The gelling agent is not particularly limited, and various polymer gelling agents such as carboxymethyl cellulose, polyacrylic acid, and polyacrylic acid that are conventionally used in alkaline batteries can be used. . The content of the gelling agent in the gelled negative electrode is preferably 1.5 to 3% by mass, for example.

  Moreover, there is no restriction | limiting in particular as electrolyte solution concerning a negative electrode, The thing similar to the electrolyte solution currently used for the alkaline battery which has a conventionally known gelled negative electrode (For example, potassium hydroxide, sodium hydroxide, etc.) From the viewpoint of improving the discharge characteristics of the battery, it is more preferable to use an aqueous potassium hydroxide solution.

  The alkali concentration in the electrolytic solution is not particularly limited and may be the same as that of a conventionally known alkaline battery. For example, when an aqueous potassium hydroxide solution is used as the electrolytic solution, the potassium hydroxide concentration is 28 It is preferable to set it to -38 mass%.

  The gelled negative electrode can be prepared, for example, by a method of mixing a zinc alloy powder and an electrolytic solution that has been previously gelled using the gelling agent. In the case of using the indium compound, for example, it may be previously mixed with zinc alloy powder and then mixed with a gel electrolyte, or the zinc alloy powder and gel electrolyte may be mixed. It may be added during mixing. Furthermore, you may prepare a gelled negative electrode by methods other than these.

  The content of the zinc alloy powder in the gelled negative electrode is, for example, preferably 60% by mass or more, more preferably 65% by mass or more, and preferably 75% by mass or less. More preferably, it is 70 mass% or less. When the indium compound is contained in the negative electrode, the content is preferably 0.003 to 0.05% by mass.

  The alkaline battery of the present invention only needs to have the above-described gelled negative electrode and negative electrode current collector rod, and there are no particular restrictions on the other configurations and structures. Conventionally known cylindrical alkaline batteries (alkaline primary) Each structure and structure employed in the battery) can be applied.

<Positive electrode>
The positive electrode according to the alkaline battery of the present invention includes, for example, an active material such as manganese dioxide, nickel oxyhydroxide, a conductive additive, and an electrolyte for forming and a binder to form a positive electrode mixture. It is formed by pressing the mixture into a ring shape or the like.

The positive electrode active material preferably has a BET specific surface area of 40 m ² / g or more and 100 m ² / g or less. If the BET specific surface area of the positive electrode active material is too small, the moldability is good, but the reaction area is small and the reaction efficiency is deteriorated, which may reduce the load characteristics of the battery. Moreover, when the BET specific surface area of a positive electrode active material is too large, reaction efficiency will improve, but since a bulk density falls, a moldability may deteriorate. To enhance the moldability of the positive electrode active material, in order to improve the strength of the molded body of the positive electrode mixture, more preferably a BET specific surface area of the positive electrode active material is less than 60 m 2 / ^g, also, 45 m ² / More preferably, it is g or more.

  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 using a specific surface area measurement device (Macsorb HM model-1201 manufactured by Mounttech) using a nitrogen adsorption method.

  Moreover, when using manganese dioxide as a positive electrode active material, it is desirable for manganese dioxide to contain 0.01-3.0 mass% of titanium. With manganese dioxide containing this amount of titanium, the specific surface area is increased and the reaction efficiency is improved, so that the load characteristics of the alkaline battery can be further improved.

  For example, graphite, ketjen black, acetylene black, or the like can be used as the conductive assistant for the positive electrode. The amount of the conductive additive in the positive electrode mixture is preferably, for example, 3 to 8.5 parts by mass with respect to 100 parts by mass of the positive electrode active material.

  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.

  As an electrolytic solution used for the positive electrode, for example, an alkaline aqueous solution in which an alkali metal hydroxide such as potassium hydroxide, sodium hydroxide, or lithium hydroxide is dissolved in water, or a solution in which zinc oxide or the like is added thereto is used. However, as will be described later, an aqueous potassium hydroxide solution is more preferable from the viewpoint of improving 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%.

<Ratio of negative electrode capacity to positive electrode capacity>
As described above, gas generation in the battery at the time of overdischarge is caused by unreacted Zn (Zn component in the zinc alloy related to the zinc alloy powder) that is not involved in the discharge reaction in the negative electrode after the discharge of the battery is completed. ) Occurs. Therefore, in the battery of the present invention, the ratio of the negative electrode capacity to the positive electrode capacity (negative electrode capacity / positive electrode capacity) is preferably 1.25 or less, more preferably 1.20 or less, and 1.10 or less. More preferably. Thus, by reducing the ratio of the negative electrode capacity to the positive electrode capacity, the amount of unreacted Zn at the end of discharge can be reduced as much as possible, and gas generation at the time of overdischarge can be further suppressed.

  In addition, if the ratio of the negative electrode capacity to the positive electrode capacity is too small, the balance between the positive electrode capacity and the negative electrode capacity is deteriorated and the discharge capacity of the battery may be reduced. The ratio is preferably 1.00 or more, and more preferably 1.05 or more.

  The ratio of the negative electrode capacity to the positive electrode capacity in the battery of the present invention is a value determined as follows. The content of the positive and negative electrode active materials after battery assembly is calculated from the mass of the positive electrode active material (manganese dioxide or nickel oxyhydroxide) and the analytical values of the Mn content and Ni content therein. And about a negative electrode active material (Zn component in a zinc alloy), after collect | recovering gel-like negative electrode mixtures and washing with water, it analyzes and calculates Zn content rate. The Mn content and Ni content in the positive electrode active material and the Zn content in the negative electrode active material are determined by inductively coupled plasma (ICP) analysis. Then, the capacity of manganese dioxide is set to 308 mAh / g, the capacity of nickel oxyhydroxide is set to 292 mAh / g, the positive electrode capacity is calculated from the positive electrode active material content (the amount of manganese dioxide and the amount of nickel oxyhydroxide), and zinc The negative electrode capacity is calculated from the negative electrode active material content (Zn amount), and the ratio of the negative electrode capacity to the positive electrode capacity is obtained.

The capacities of manganese dioxide, nickel oxyhydroxide and zinc are shown in Tables 1 and 4 “units of various battery active materials” on page 27 of “Battery Handbook 3rd Edition (Maruzen Co., Ltd.)”. The value obtained by taking the reciprocal of the mass per unit quantity of electricity (1.220, 3.244, and 3.422) of Zn, MnO ₂ and NiOOH in “mass and volume per quantity of electricity” was used.

<Electrolyte>
As an electrolytic solution for injecting into a battery other than for use in the positive electrode and the negative electrode, for example, an alkali metal such as potassium hydroxide, sodium hydroxide, lithium hydroxide, etc., similar to the electrolytic solution related to the positive electrode and the negative electrode. An aqueous alkali solution composed of an aqueous solution of the above-mentioned hydroxide, or a solution in which zinc oxide is added thereto can be used. For example, in the case of potassium hydroxide, the concentration of the alkali metal hydroxide in the electrolytic solution is preferably 28 to 38% by mass. When zinc oxide is used, the concentration is 1.0 to It is preferable that it is 4.0 mass%.

  In addition, from the viewpoint of improving the discharge characteristics of the battery, an aqueous potassium hydroxide solution can be used for any of the electrolyte for positive electrode, the electrolyte for negative electrode, and the electrolyte for injecting into the battery other than the positive electrode and negative electrode. And the concentration of each electrolyte solution is adjusted so that the average potassium hydroxide concentration in the electrolyte solution in the battery system is preferably 38% by mass or less, more preferably 35% by mass or less. It is desirable to do.

  When the potassium hydroxide concentration in the electrolyte solution in the battery system is high, the ionic conductivity of the electrolyte solution is low, and such an electrolyte solution is used in combination with a negative electrode having a zinc alloy powder in a fine form as described above, for example. Then, it is estimated that the electrical resistance of the discharge product formed on the surface of the zinc alloy powder increases. Therefore, the temperature at the time of short-circuiting of the battery becomes very high, which may impair safety, and the utilization rate of the Zn component in the zinc alloy powder also decreases, and the amount of unreacted Zn component increases at the end of discharge. There is a possibility that the effect of suppressing gas generation during overdischarge may be reduced.

  Therefore, if the average value of the potassium hydroxide concentration in the electrolyte solution in the battery system is set low as described above, the electrical resistance of the electrolyte solution is lowered and a discharge product with low resistance is generated on the surface of the zinc alloy powder. It is possible to increase the safety by reducing the temperature rise at the time of short circuit of the battery, and further improve the utilization rate of the Zn component in the zinc alloy related to the zinc alloy powder, at the end of the discharge It is also possible to further reduce the amount of unreacted Zn component.

  However, if the potassium hydroxide concentration in the electrolyte solution is too low, the ionic conductivity of the electrolyte solution tends to decrease. Therefore, the potassium hydroxide concentration in the electrolyte solution in the battery system is preferably averaged. Is 28% by mass or more, more preferably 30% by mass or more, and each water of the electrolyte for pouring into the battery in addition to being used for the positive electrode electrolyte, the negative electrode electrolyte, the positive electrode and the negative electrode. It is desirable to adjust the potassium oxide concentration.

<Separator>
The separator for the alkaline battery of the present invention is not particularly limited. For example, a nonwoven fabric mainly composed of vinylon and rayon, a vinylon / rayon nonwoven fabric (vinylon / rayon mixed paper), a polyamide nonwoven fabric, a polyolefin / rayon nonwoven fabric, a vinylon paper, a vinylon. -Linter pulp paper, vinylon mercerized pulp paper, etc. can be used. In addition, a separator in which a hydrophilic microporous polyolefin film (such as a microporous polyethylene film or a microporous polypropylene film), a cellophane film, and a liquid absorbing layer such as vinylon / rayon mixed paper may be used as a separator. .

  The alkaline battery of the present invention can be applied to the same applications as those in which conventionally known alkaline batteries are used.

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

Example 1
Manganese dioxide, graphite, polytetrafluoroethylene powder containing 1.6% by mass of water, and an alkaline electrolyte for preparing a positive electrode mixture (56% by mass of potassium hydroxide containing 2.9% by mass of zinc oxide) 87 A positive electrode mixture was prepared by mixing at a mass ratio of .6: 6.7: 0.2: 5.5 at a temperature of 50.degree. In this positive electrode mixture, graphite was 7.6 parts by mass with respect to 100 parts by mass of manganese dioxide. Moreover, the potassium hydroxide concentration of the electrolyte solution contained in the positive electrode mixture was 44.6% by mass in consideration of the moisture content of manganese dioxide.

Next, a powder composed of a zinc alloy containing 1000 ppm Al, 100 ppm Bi, 500 ppm In, and 5 ppm Mg, sodium acrylate, polyacrylic acid, and an alkaline electrolyte for preparing a negative electrode mixture (zinc oxide) 33.5 mass% potassium hydroxide aqueous solution containing 2.2 mass%) was mixed at a mass ratio of 39: 0.2: 0.2: 18 to prepare a gelled negative electrode mixture. The zinc alloy powder has an average particle size of 109 μm, passes through all 80 mesh screens, and passes through 200 mesh screens, and the zinc alloy powder is 25 mass% with respect to the total zinc alloy powder amount. The bulk density was 2.63 g / cm ³ .

  Further, as an outer can, an outer can 1 for an AA alkaline battery made of a killed steel plate having a matte Ni plating on the surface and having the shape shown in FIG. 2 was prepared. The outer can 1 has a sealing portion 10 having a thickness of 0.25 mm and a barrel 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 can thickness of the part is made slightly thicker than the body part 20. Using this outer can 1, an alkaline battery was produced as follows.

About 11 g of the positive electrode mixture: inserted into the outer can 1 and press-molded into a bobbin shape (hollow cylindrical shape). The inner diameter is 9.1 mm, the outer diameter is 13.7 mm, and the height is 13.9 mm. Three positive electrode mixture molded bodies (density: 3.21 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.

Next, a nonwoven fabric made of acetalized vinylon having a thickness of 100 μm and a basis weight of 30 g / m ² and tencel is overlapped in a cylinder, wound into a cylindrical shape, the bottom portion is bent, this portion is heat sealed, and one end is closed The cup-shaped separator 3 thus obtained was obtained. This separator 3 is loaded inside the positive electrode 1 inserted into the outer can 1, and an alkaline electrolyte for injection (33.5 mass% potassium hydroxide aqueous solution containing 2.2 mass% zinc oxide) 35 g was injected into the inner side of the separator, and 5.74 g of the negative electrode mixture was further filled into the inner side of the separator 3 to obtain the negative electrode 4. At this time, the water content in the battery system was 0.261 g per 1 g of the positive electrode active material, and the ratio of the negative electrode capacity to the positive electrode capacity was 1.10. Moreover, the potassium hydroxide concentration of the electrolyte solution in the battery system was adjusted to 34.5% by mass.

  After filling the power generating element, the negative electrode current collector rod 5 made of brass having a Sn plating layer (thickness 1.50 μm) formed on the surface thereof by an electrolytic plating method is combined with a sealing body 6 made of nylon 66, and the negative electrode current collector rod 5 is By inserting into the center of the negative electrode 4 and caulking from the outside of the open end 1a of the outer can 1 by a spinning method, the AA alkaline battery shown in FIG. The negative electrode current collector rod 5 is attached in advance to a negative electrode terminal plate 7 made of a nickel-plated steel plate having a thickness of 0.4 mm formed by punching 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. The cylindrical alkaline battery of Example 1 was produced as described above.

Example 2
A cylindrical alkaline battery was produced in the same manner as in Example 1 except that the zinc alloy powder was changed to a powder composed of a zinc alloy containing 300 ppm Al, 100 ppm Bi, 500 ppm In, and 5 ppm Mg. . In addition, the zinc alloy powder used in Example 2 has the same average particle diameter, the ratio of the powder passing through a 200 mesh sieve, and the bulk density used in Example 1 (implementation described below) The same applies to Examples 3 and 4 and Comparative Examples 1 to 4.)

Example 3
A cylindrical alkaline battery was produced in the same manner as in Example 1 except that the zinc alloy powder was changed to a powder composed of a zinc alloy containing 1000 ppm Al, 100 ppm Bi, 500 ppm In, and 5 ppm Ca. .

Example 4
A cylindrical alkaline battery was produced in the same manner as in Example 1 except that the thickness of the Sn plating layer in the negative electrode current collecting rod 5 was changed to 0.80 μm.

Comparative Example 1
The zinc alloy powder was changed to a powder made of a zinc alloy containing Al at 30 ppm, Bi at 150 ppm, and In at a ratio of 500 ppm, and the Sn plating layer in the negative electrode current collector rod 5 was formed by electroless plating, and the thickness was 0 A cylindrical alkaline battery was produced in the same manner as in Example 1 except that the thickness was 0.05 μm.

Comparative Example 2
A cylindrical alkaline battery was produced in the same manner as in Example 1 except that the Sn plating layer in the negative electrode current collector rod 5 was formed by electroless plating and the thickness was 0.05 μm.

Comparative Example 3
A cylindrical alkaline battery was produced in the same manner as in Example 1 except that the zinc alloy powder was changed to a powder made of a zinc alloy containing 30 ppm Al, 150 ppm Bi, and 500 ppm In.

Comparative Example 4
A cylindrical alkaline battery was produced in the same manner as in Example 1 except that the zinc alloy powder was changed to a powder made of a zinc alloy containing 1000 ppm Al, 150 ppm Bi, 500 ppm In, and 5 ppm Mg. .

  Each of the following evaluations was performed on the cylindrical alkaline batteries of Examples 1 to 4 and Comparative Examples 1 to 4. These results are shown in Table 1.

<Gas amount confirmation test during overdischarge>
Each cylindrical alkaline battery was discharged at 20 ° C. and 10Ω for 48 hours to be in an overdischarged state, and then held at 20 ° C. for 120 hours, and then the amount of gas inside the battery was measured. In measuring the amount of gas, a water replacement method was adopted in which the battery was disassembled in water and the gas in the battery was collected. Moreover, each said gas amount measurement used 5 batteries of Examples 1-4 and Comparative Examples 1-4 respectively, and calculated | required the average value of these results. In Table 1, the evaluation results of the batteries of the examples and comparative examples are shown as relative values when the result of the battery of comparative example 1 is 100.

<Verification test of gas generation from negative electrode current collector>
In the batteries of the examples and comparative examples, it is difficult to measure only the amount of gas generated from the negative electrode current collector rod when not discharged. Therefore, the negative electrode current collector rod used in each battery and the zinc alloy related to the negative electrode A model test of gas generation was performed using the powder.

  Into each 10 g of the same zinc alloy powder used for the production of the batteries of each Example and Comparative Example, 5 negative electrode current collecting rods used for the production of the batteries of each Example and Comparative Example were charged, The zinc alloy powder related to the negative electrode was brought into contact with the negative electrode current collector rod. Here, 5 ml of the same alkaline electrolyte solution for injection (33.5 mass% potassium hydroxide aqueous solution containing 2.2 mass% of zinc oxide) as that used for the production of each battery was added. These were sealed with liquid paraffin and stored at 60 ° C. for 72 hours, and the amount of gas generated at that time was measured. In Table 1, the evaluation results of the examples and comparative examples are shown as relative values when the result of comparative example 1 is set to 100. That is, as a result of the above, it is considered that the larger the relative value of the gas generation amount, the larger the amount of gas generated due to the negative electrode current collector rod in the actual battery (in the battery when not discharged).

  As is clear from Table 1, in Examples 1 to 4, the amount of gas generated from the negative electrode current collector rod is small, and the Sn plating layer provided on the surface of the negative electrode current collector rod provides good gas generation in the battery when not discharged. In addition, the amount of gas generated in the battery at the time of overdischarge is small, and the gas at the time of overdischarge due to Sn eluted from the Sn plating layer having a large thickness and the remaining Zn component not involved in the discharge Occurrence is well suppressed.

  On the other hand, in Comparative Example 1 using a negative electrode current collector with a small amount of Al, no Mg and Ca, a large amount of Bi, and a thin Sn plating layer, a negative electrode current collector rod was used. The amount of gas generated from the electric rod is large, and it is considered that the suppression of gas generation in the battery during undischarge is insufficient, and the suppression of gas generation during overdischarge is also insufficient. Further, in Comparative Example 2 using the negative electrode current collector rod with a thin Sn plating layer, the amount of gas generated from the negative electrode current collector rod is large, and it is considered that the suppression of gas generation in the battery when not discharged is insufficient. Further, in Comparative Example 3 using a zinc alloy powder having a small amount of Al, not containing Mg and Ca, and having a large amount of Bi, and Comparative Example 4 using a zinc alloy powder having a large amount of Bi, overdischarge Insufficient suppression of gas generation.

It is sectional drawing which shows an example of the alkaline battery of this invention. It is sectional drawing which shows the other example of the alkaline battery of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Exterior can 2 Positive electrode 3 Separator 4 Negative electrode 5 Negative electrode current collecting rod 6 Sealing body made of resin 7 Negative electrode terminal plate 8 Insulating plate 9 Metal washer 63 Thin-walled portion for explosion protection

Claims (7)

It has a gelled negative electrode containing zinc alloy powder and an electrolytic solution composed of an alkaline aqueous solution, and at least one end is immersed in the gelled negative electrode, and the other end is electrically connected to the negative terminal plate. A cylindrical alkaline battery having a negative electrode current collector,
The zinc alloy contains Bi of 50 to 125 ppm, Al of 100 to 2000 ppm, and at least one of Ca and Mg in total of 1 to 50 ppm,
The negative electrode current collector rod is made of brass and has an Sn plating layer having a thickness of 0.6 μm or more on the surface thereof.   The alkaline battery according to claim 1, wherein the zinc alloy contains 100 to 1000 ppm of In.   The alkaline battery according to claim 1, wherein the Sn plating layer of the negative electrode current collector rod is formed by an electrolytic plating method.   The alkaline battery according to any one of claims 1 to 3, wherein a ratio of the zinc alloy powder that can pass through a 200 mesh sieve is 10 to 80% by mass.   5. The alkaline battery according to claim 4, wherein a ratio of the zinc alloy powder that can pass through a 200-mesh sieve is 40% by mass or less.   The alkaline battery according to claim 1, wherein the ratio of the negative electrode capacity to the positive electrode capacity is 1.00 to 1.25.   The alkaline battery according to claim 1, wherein the electrolytic solution is an aqueous potassium hydroxide solution, and the concentration of potassium hydroxide in the electrolytic solution in the battery system is 30 to 35% by mass on average.

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