JP2013004250A - Alkaline dry cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an alkaline dry cell that has an excellent resistance characteristic to liquid leakage not only under a non-discharge state and a partial discharge state, but also under an over-discharge state.SOLUTION: The distance between a separator and a negative electrode collector is bisected in a negative electrode 3 so that the volume thereof is equally divided into two parts. When one part at the separator side is set as a positive electrode facing portion 3-2 and the other part at the negative electrode collector side is set as a negative electrode collector facing portion 3-1, the average concentration of aluminum contained in the positive electrode facing portion 3-2 is set to be higher than the average concentration of aluminum contained in the negative electrode collector facing portion 3-1, whereby occurrence of hydrogen gas after over-discharge can be suppressed with the minimum aluminum addition amount.

Description

  The present invention relates to an alkaline battery.

  Alkaline batteries using manganese dioxide for the positive electrode, zinc for the negative electrode, and an alkaline aqueous solution for the electrolyte are inexpensive and are widely used as power sources for various devices.

  Conventionally, zinc is used as a negative electrode material for alkaline batteries. In a battery using zinc as a negative electrode active material, a corrosion reaction accompanied by hydrogen generation from zinc occurs vigorously, which causes an increase in battery internal pressure and occurrence of leakage. Therefore, the leakage resistance reliability of the alkaline battery is greatly improved by suppressing the corrosion of zinc in the alkaline electrolyte.

  Examples of the central anticorrosion technique for zinc include a technique for enhancing corrosion resistance by alloying at least one of anticorrosive elements such as aluminum, indium, bismuth and calcium with zinc (see, for example, Patent Document 1). Indium and bismuth have high hydrogen overpotential of their elements, and when added to zinc, they have the effect of increasing the hydrogen overvoltage on the zinc surface. In addition, aluminum has a function of smoothing the surface of zinc particles, and since the specific surface area of zinc is reduced, it is also known that the corrosion amount per unit weight of a zinc alloy is reduced (see, for example, Patent Document 2). ). As content of the anticorrosive element in the zinc alloy of a general alkaline dry battery, for example, aluminum is 0.003-0.006 weight% with respect to the zinc alloy whole quantity (for example, refer patent document 3), indium is a zinc alloy. The amount is 0.0001 to 0.02% by weight based on the total amount (for example, see Patent Document 4), and bismuth is 0.001 to 0.015% by weight (for example, see Patent Document 5) with respect to the total amount of the zinc alloy. With these technologies, the alkaline battery during non-discharge storage ensures liquid leakage.

  The anticorrosive element added to the negative electrode zinc alloy as an anticorrosive element is difficult to disperse uniformly in the zinc alloy for manufacturing reasons, and is mainly present near the surface of the zinc alloy. When discharged, the zinc surface containing no anticorrosive element comes into contact with the electrolyte. For this reason, in a partially discharged battery, the hydrogen gas generation rate of the zinc negative electrode is accelerated, and the liquid leakage resistance is deteriorated.

  In addition, when using a plurality of alkaline batteries connected in series, in a battery that has fallen into a deep discharge state (overdischarge state), the dissolution of the negative electrode zinc further proceeds, and the anticorrosive elements are eluted into the electrolyte. As the hydrogen generation overvoltage decreases due to hydrogen, hydrogen gas is generated, and the leak-proof characteristics further deteriorate. On the other hand, by suppressing the addition amount of the anticorrosive element, a certain suppression effect is obtained with respect to hydrogen gas generation. However, when the amount of the anticorrosive element increases (the weight of the substance (anticorrosive element) other than zinc increases), the reaction efficiency of zinc decreases, so that the content itself is preferably small (for example, Patent Document 6).

  As described above, the content of the anticorrosive element in the zinc alloy used for the negative electrode is preferably higher from the viewpoint of suppressing the generation of hydrogen gas, but is preferably lower from the viewpoint of securing the discharge capacity.

Japanese Patent Publication No. 3-71737 JP 2010-10012 A JP 2008-171767 A JP 2009-64756 A International Publication No. 2008/018455 JP 2009-170157 A

  SUMMARY OF THE INVENTION The present invention solves the above-described conventional problems, and an object thereof is to provide an alkaline dry battery having excellent leakage resistance not only in an undischarged state or a partial discharge state but also in an overdischarged state.

  The alkaline dry battery of the present invention includes a negative electrode, a negative electrode current collector in contact with the negative electrode, a separator in contact with the negative electrode on the side opposite to the negative electrode current collector, and a positive electrode facing the negative electrode through the separator. And a positive electrode current collector in contact with the positive electrode on the opposite side of the separator, and an alkaline electrolyte impregnated in the negative electrode, the positive electrode and the separator. The negative electrode is composed of a zinc alloy powder dispersed as a negative electrode active material. In the negative electrode, the distance between the separator and the negative electrode current collector is divided into two so as to divide the volume into two equal parts, and when the separator side is the positive electrode facing portion and the negative electrode current collector side is the negative electrode current collector facing portion, The object is achieved by making the average concentration of aluminum contained in the positive electrode facing portion higher than the average concentration of aluminum contained in the negative electrode current collector facing portion. Here, it is assumed that the zinc alloy contained in the negative electrode current collector facing portion and the zinc alloy contained in the positive electrode facing portion have the same weight.

  ADVANTAGE OF THE INVENTION According to this invention, the alkaline dry battery excellent in the leak-proof characteristic not only in a non-discharge state and a partial discharge state but in an overdischarge state can be provided.

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

  In the present invention, attention has been paid to aluminum that is inexpensive and easily available from among the commonly used anticorrosive elements from the viewpoint of improving the liquid leakage of alkaline batteries. The aluminum content in the zinc alloy is preferably higher from the viewpoint of suppressing the generation of hydrogen gas, but is preferably lower from the viewpoint of securing the discharge capacity. Therefore, in the present invention, unlike the conventional alkaline battery, the aluminum concentration in the zinc alloy used for the negative electrode is not made uniform throughout the negative electrode, but is locally changed, thereby effectively suppressing the generation of hydrogen gas. I thought. As a result of intensive studies by the present inventors, the average concentration of aluminum contained in the zinc alloy of the positive electrode facing portion 3-2 is made higher than the average concentration of aluminum contained in the zinc alloy of the negative electrode current collector facing portion 3-1. Thus, compared with the case where the aluminum concentration distribution of the zinc alloy is uniform in the negative electrode, it is clear that the effect of suppressing the generation of hydrogen gas can be enhanced with a smaller amount of aluminum without reducing the battery performance. I made it.

  FIG. 1 shows a cross-sectional view of an example of the alkaline dry battery of the present invention.

As shown in FIG. 1, the alkaline battery includes a cylindrical battery case 1 that is sealed at one end (the lower end in FIG. 1), and the outer peripheral surface of the battery case 1 is covered with an exterior label 8. The battery case 1 serves as both a positive electrode terminal and a positive electrode current collector. A hollow cylindrical positive electrode 2 is inscribed in the battery case 1. A separator 4 is provided in the hollow part of the positive electrode 2, and the separator 4 is formed in a cylindrical shape sealed at one end, and the gelled negative electrode 3 characterized by the present invention is provided in the hollow part of the separator 4. It has been. In the negative electrode, the distance between the separator and the negative electrode current collector is divided into two so as to divide the volume into two equal parts, the separator side is the positive electrode facing portion 3-2, and the negative electrode current collector side is the negative electrode current collector facing portion 3- Set to 1. As described above, in the battery case 1, the positive electrode 2, the separator 4, the positive electrode facing portion 3-2, and the negative electrode current collector facing portion 3-1 are arranged in this order from the periphery toward the center.

  As the negative electrode 3, a material obtained by adding a gelling agent such as polyacrylic acid to an alkaline electrolyte and processing the gel, and dispersing zinc alloy particles in the gel material is used.

  The aluminum content of the zinc alloy in the negative electrode current collector facing portion 3-1 does not significantly affect the amount of hydrogen gas generated. On the other hand, the addition of high concentration of aluminum in the positive electrode facing portion 3-2 produces an effect of suppressing generation of hydrogen gas.

  The aluminum content of the zinc alloy in the negative electrode current collector facing portion 3-1 is 0.001% by weight or more from the viewpoint of the minimum hydrogen gas generation suppression. Moreover, 0.006 weight% or less is preferable from a viewpoint of ensuring discharge capacity.

  The aluminum content of the zinc alloy in the positive electrode facing portion 3-2 is 0.003% by weight or more, preferably 0.005% by weight or more, and more preferably 0.03% by weight or more from the viewpoint of suppressing hydrogen gas generation. However, since the discharge capacity tends not to be secured when the amount of aluminum increases, the content of aluminum in the zinc alloy is preferably small. The content is preferably 0.1% by weight or less.

  It is a feature of the present application that the aluminum content of the zinc alloy in the negative electrode current collector facing portion 3-1 is less than that of the positive electrode facing portion 3-2.

  The aluminum concentration distribution of the zinc alloy in the negative electrode current collector facing portion 3-1 and the positive electrode facing portion 3-2 is not necessarily uniform, and the average value may be the value described above. For example, in the vicinity of the boundary between the negative electrode current collector facing portion 3-1 and the positive electrode facing portion 3-2, there is a decrease in the amount of aluminum from the positive electrode facing portion 3-2 to the negative electrode current collector facing portion 3-1, There may be a case where there is an increase or decrease in the amount of aluminum in the vicinity of the negative electrode current collector or separator.

  For the same reason, the distance between the separator and the negative electrode current collector is divided into two so as to divide the volume of the negative electrode 3 into two equal parts, but the concentration does not necessarily change discontinuously at this point. In short, the aluminum content of the zinc alloy in the negative electrode current collector facing portion 3-1 should be less than that of the positive electrode facing portion 3-2.

  Moreover, as a form containing aluminum of a negative electrode, although it may be alloyed with zinc and does not need to be alloyed, the form alloyed is desirable. As a form which is not alloyed, for example, there is a form in which aluminum hydroxide and a zinc alloy are dispersed.

  The opening (lower end in FIG. 1) of the battery case 1 is sealed by an assembly sealing body 9. The assembly sealing body 9 is obtained by integrating a nail-type negative electrode current collector 6, a negative electrode terminal plate 7, and a resin sealing body 5. The negative electrode terminal plate 7 is electrically connected to the negative electrode current collector 6. The resin sealing body 5 is physically fixed to the negative electrode current collector 6 and the negative electrode terminal plate 7.

  The positive electrode 2, the negative electrode 3, and the separator 4 contain an alkaline electrolyte. As the alkaline electrolyte, an aqueous solution containing 30 to 40% by weight of potassium hydroxide and 1 to 3% by weight of zinc oxide is used.

In general, the positive electrode 2 is located on the outer periphery of the negative electrode 3 with the negative electrode current collector 6 inserted as shown in FIG. 1 via a separator, but the negative electrode is located on the outer periphery of the positive electrode via a separator. If the conditions of the aluminum content of a negative electrode are satisfy | filled, the same effect will be acquired. In that case, the battery case serves as the negative electrode current collector.

  Examples of the present invention are shown below. In this example, an AA alkaline battery was manufactured according to the method described below, then overdischarged, the negative electrode taken out after battery decomposition was immersed in KOH solution, and the amount of hydrogen generated by zinc self-corrosion was measured. The hydrogen gas generation suppression effect of the present invention was confirmed.

(Method for producing AA alkaline battery of Example 1)
First, a gelling agent was added to a 34.5% by weight potassium hydroxide aqueous solution (containing 2% by weight of ZnO) and mixed to cause gelation. As a result, a gel electrolyte was obtained. As the gelling agent, various polymer gelling agents such as polyacrylic acid and sodium polyacrylate can be used. Each weight ratio is weight of potassium hydroxide aqueous solution: weight of gelling agent = 100: 2.2.
Thereafter, the gel electrolyte solution obtained above was allowed to stand for 24 hours and sufficiently aged.

  Furthermore, 0.005 wt% aluminum-containing zinc alloy particles produced by a gas atomizing method and a phosphoric acid surfactant were sufficiently mixed with the gel electrolyte solution obtained above. Each weight ratio is gel electrolyte solution: aluminum containing 0.005% by weight of zinc alloy particles: phosphate surfactant = 50: 100: 0.005. Thereby, a gelled negative electrode having a low aluminum concentration was obtained. On the other hand, using a zinc alloy particle containing 0.06% by weight of aluminum, a gelled negative electrode having a high aluminum concentration was obtained in the same manner.

  First, manganese dioxide and graphite were blended in a weight ratio of 94: 6 to obtain a mixed powder. Then, 1.5 parts by weight of an electrolytic solution (39% by weight potassium hydroxide aqueous solution (containing 2% by weight of ZnO)) and 0.2 parts by weight of a polyethylene binder were mixed with 100 parts by weight of the mixed powder. Thereafter, the mixture was uniformly stirred and mixed with a mixer to adjust the particle size to a constant particle size, and the resulting granular material was pressed into a hollow cylindrical shape. In this way, a positive electrode mixture pellet was obtained.

  Subsequently, an AA alkaline battery for evaluation was produced. Specifically, as shown in FIG. 1, four positive electrode mixture pellets (the weight of one is 2.95 g) obtained above are inserted into the battery case 1, and the battery case 1 is reused in the battery case 1. The pressure was applied to the inner surface of the battery case 1. And after inserting the separator 4 and the base paper for insulating the bottom part of the battery case 1 inside this positive mix pellet, electrolyte solution (34.5 weight% potassium hydroxide aqueous solution (ZnO 2 weight%) 1.5 g) was injected. After injection, 3.1 g of the gelled negative electrode having a low aluminum concentration was applied to the negative electrode current collector facing portion 3-1 (the weight of the zinc alloy particles was 2.05 g), and the gelled negative electrode having a high aluminum concentration was connected to the positive electrode facing portion The 3-2 portion was filled with 3.1 g, and a negative electrode having a higher aluminum concentration in the positive electrode facing portion 3-2 than in the negative electrode current collector facing portion 3-1 was obtained.

  Thereafter, the opening of the battery case 1 was sealed using an assembly sealing body 9 in which the resin sealing body 5, the negative electrode terminal plate 7, and the negative electrode current collector 6 were integrated. Specifically, the negative electrode current collector 6 is inserted into the negative electrode 3, and the peripheral edge portion of the negative electrode terminal plate 7 is crimped to the edge of the opening of the battery case 1 through the end portion of the resin sealing body 5, thereby 7 was brought into close contact with the opening of the battery case 1. Then, the outer surface of the battery case 1 was covered with an exterior label 8 to produce an AA alkaline battery according to the example.

(Manufacturing method of the AA alkaline battery of Comparative Example 1)
The method for producing the constituent components is the same as in the above examples. At the time of producing an AA alkaline battery for evaluation, the separator 4 and a bottom paper for insulating the bottom of the battery case 1 were inserted inside the positive electrode mixture pellet, and then 1.5 g of electrolyte was injected, The gelled negative electrode with a high aluminum concentration is 3.1 g (the weight of zinc alloy particles is 2.05 g) in the negative electrode current collector facing portion 3-1, and the gelled negative electrode with a low aluminum concentration is 3 in the positive electrode facing portion 3-2. 0.1 g was filled, and a negative electrode having a higher aluminum concentration in the negative electrode current collector facing portion 3-1 than in the positive electrode facing portion 3-2 was obtained. Except for this, an AA alkaline battery for Comparative Example 1 was produced in the same manner as in the method for producing an AA alkaline battery according to the above example.

(Method for producing AA alkaline battery of Comparative Example 2)
Using zinc alloy particles containing 0.005% by weight of aluminum produced by gas atomization method, and each weight ratio is a gel-like electrolyte solution as in the example: zinc particles containing 0.005% by weight of aluminum: phosphate surfactant = A gelled negative electrode with a low aluminum concentration of 50: 100: 0.005 was obtained. In Comparative Example 1, since the aluminum concentration in the entire negative electrode was 0.005% by weight, there is no distinction between the negative electrode current collector facing portions 3-1 and 3-2.

  When producing an AA alkaline battery for evaluation, the separator 4 and a bottom paper for insulating the bottom of the battery case 1 were inserted inside the positive electrode mixture pellet, and then 1.5 g of an electrolytic solution was injected, and the separator 4 The gel-like negative electrode 3 was filled in 6.2 g (zinc alloy particle weight is 4.1 g). Thereafter, the opening of the battery case 1 was sealed using an assembly sealing body 9 in which the resin sealing body 5, the negative electrode terminal plate 7, and the negative electrode current collector 6 were integrated. Except for this, an AA alkaline battery for Comparative Example 2 was produced in the same manner as in the method for producing an AA alkaline battery according to the above example.

(Manufacturing method of the AA alkaline battery of Comparative Example 3)
Zinc alloy particles containing 0.06% by weight of aluminum, each produced by a gas atomization method, were used. Except for this, an AA alkaline battery of Comparative Example 3 was produced in the same manner as in the method for producing an AA alkaline battery of Comparative Example 2 above.

(Evaluation of hydrogen gas amount)
One battery of Example 1 or a comparative example and three AA alkaline batteries that are generally commercially available are connected in series, and a constant resistance discharge is performed with a resistance element (16Ω) in a room temperature environment. One battery was overdischarged, and the circuit was cut off when the discharge capacity thereafter became substantially the same. After the battery was disassembled, the negative electrode was taken out and sealed in a glass container (sample tube).

  A KOH aqueous solution (43 wt%) was added to the glass container, and the negative electrode was immersed therein. The amount of hydrogen gas generated by corrosion of zinc in KOH aqueous solution was collected by water displacement and measured.

  The amount of generated hydrogen gas was converted per unit weight of residual zinc in order to evaluate the original gas generation suppression effect. Table 1 shows the amount of hydrogen gas generated per unit weight of residual zinc after 130 hours and the discharge capacity when 1V is reached. The trend was similar for the amount of gas generated after 130 hours.

  When the aluminum concentration of the zinc alloy is the same throughout the negative electrode (the aluminum concentration of the negative electrode current collector facing portion 3-1 = the aluminum concentration of the positive electrode facing portion 3-2), the comparative example 3 is more hydrogen than the comparative example 2. The amount of gas generated is small. This indicates that the higher the aluminum concentration contained in the zinc alloy, the higher the hydrogen gas suppression effect.

  When Example 1 and Comparative Example 1 are compared, the amount of hydrogen gas generated is smaller in Example 1 in which the aluminum concentration in the positive electrode facing portion 3-2 is higher than the aluminum concentration in the negative electrode current collector facing portion 3-1. The negative electrode current collector facing portion 3-1 and the positive electrode facing portion 3-2 have the same weight, and the entire negative electrode of Example 1 and Comparative Example 1 (the negative electrode current collector facing portion 3-1 and the positive electrode facing portion 3-2). The amount of aluminum contained in the total) is equal. Therefore, while maintaining the amount of aluminum contained in the entire negative electrode, by making the aluminum concentration in the positive electrode facing portion 3-2 higher than the aluminum concentration in the negative electrode current collector facing portion 3-1, it is possible to effectively generate hydrogen gas. It was confirmed that suppression was possible.

  Comparing Comparative Example 1 and Comparative Example 2, although the amount of aluminum contained in the whole negative electrode is larger in Comparative Example 1, the amount of hydrogen gas generated is almost the same. From this, even if the aluminum concentration of the negative electrode current collector facing portion 3-1 is increased, it is considered that the hydrogen gas generation suppressing effect does not change. Therefore, it has been clarified that the influence of the aluminum concentration in the negative electrode current collector facing portion 3-1 on the hydrogen gas generation amount is small.

  Example 1 generates less hydrogen gas than Comparative Example 2. This may be related to the fact that the amount of aluminum contained in the entire negative electrode is Example 1> Comparative Example 2. However, based on the results described above, the amount of aluminum in the positive electrode facing portion 3-2 is high. It is considered that hydrogen gas generation could be further suppressed by using an aluminum concentration-containing zinc alloy.

  The hydrogen gas generation amounts of Example 1 and Comparative Example 3 are substantially equal. It was also clarified from this comparison that the hydrogen gas generation amount greatly contributed from the hydrogen gas amount generated from the positive electrode facing portion 3-2.

  In this study, the discharge capacity (in the case of stopping 1 V) was in the order of Comparative Example 2> Comparative Example 1≈Example 1> Comparative Example 3. By providing a portion with a high aluminum concentration, the discharge capacity in Example 1 and Comparative Example 1 was lower than that in Comparative Example 2 with a low aluminum concentration. In comparison with Comparative Example 3, the discharge capacity was larger than that of Comparative Example 3. Therefore, it is considered that the effect of suppressing the generation of gas efficiently can be brought out by suppressing the reduction of the discharge capacity by the concept of the present invention.

  From the above results, it is generated from the zinc alloy of the positive electrode facing portion 3-2 rather than the negative electrode current collector facing portion 3-1, that affects the hydrogen gas generation of the overdischarge experience cell used in this study. By making the aluminum concentration of the zinc alloy of the positive electrode facing portion 3-2 higher than the aluminum concentration of the zinc alloy of the negative electrode current collector facing portion 3-1 by hydrogen gas, It became clear that an alkaline dry battery having improved leakage resistance in an overdischarged state can be provided without degrading performance. Further, it goes without saying that the same gas generation suppression effect is obtained in the undischarged and partially discharged states.

  This example is an implementation result of the alkaline dry battery having the structure shown in FIG. 1, but is not influenced by this configuration, and other configurations can be used as long as they satisfy the condition of the aluminum content of the negative electrode zinc alloy of the present invention. Needless to say, it is effective.

  The alkaline battery of the present invention has high reliability and can be suitably used for any device that uses a dry battery as a power source. This is particularly effective not only when a single cell is used but also when a multi-cell series connection is used.

DESCRIPTION OF SYMBOLS 1 Battery case 2 Positive electrode 3 Negative electrode 3-1 Negative electrode collector opposing part 3-2 Positive electrode opposing part 4 Separator 5 Sealing body 6 Negative electrode collector 7 Negative electrode terminal board 8 Exterior label 9 Assembly sealing body

Claims (2)

  A negative electrode mainly composed of zinc powder, a negative electrode current collector in contact with the negative electrode, a separator in contact with the negative electrode on the side opposite to the negative electrode current collector, a positive electrode facing the negative electrode through the separator, A positive electrode current collector in contact with the positive electrode on the side opposite to the separator; an alkaline electrolyte impregnated in the negative electrode, the positive electrode, and the separator; and the negative electrode current collector from the separator so as to bisect the volume of the negative electrode When the distance between the bodies is divided into two, the separator side is the positive electrode facing part, and the negative electrode current collector side is the negative electrode current collector facing part, the average concentration of aluminum contained in the negative electrode current collector facing part An alkaline battery having a high average concentration of aluminum contained in the positive electrode facing portion.   The alkaline dry battery according to claim 1, wherein the negative electrode is mainly composed of an alloy powder of zinc and aluminum.

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