JP2005203380A - Alkaline battery and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an alkaline battery excellent in load characteristics, high safety at short circuit, and excellent in high temperature storage characteristics and a method for producing the same.
SOLUTION: After the battery is assembled, the molded product of the positive electrode mixture used for battery assembly contains 2.4 to 4 wt% potassium hydroxide with respect to the weight of the positive electrode mixture including the electrolytic solution. The amount of water contained in the positive electrode mixture is 8.4 to 10 wt% with respect to the weight of the positive electrode mixture including the electrolytic solution.
[Selection] Figure 1

Description

  The present invention relates to an alkaline battery and a method for manufacturing the same, and further relates to an alkaline battery excellent in load characteristics and a method for manufacturing the same.

  An alkaline battery using zinc as a negative electrode active material is used as a power source for various electronic devices, and various characteristics are required depending on its use. In particular, in digital cameras that have become popular in recent years, in order to maximize the number of images that can be taken, it is necessary to increase the capacity of the battery and further improve the load characteristics such as the large current discharge characteristics. Possible battery designs are being studied.

  In order to increase the capacity of the battery, it is necessary to increase the filling amount of the active material. However, if the active material is not effectively used for discharging, the capacity cannot be increased. Therefore, simply increasing the filling amount of the active material. You can't achieve your goal by just doing it. Since the discharge capacity is determined in consideration of the utilization factor of the active material, it is necessary to design the positive electrode, the negative electrode, and the electrolytic solution so that the discharge reaction proceeds smoothly. The discharge reaction of the positive electrode of the alkaline battery using manganese dioxide as the positive electrode active material proceeds according to the following formula (1).

Positive electrode: MnO2 + H2O + e− → MnOOH + OH− (1)
As is clear from the above formula, since water is consumed at the time of discharge at the positive electrode, from the viewpoint of the discharge reaction, it is desirable that as much water as possible exists on the positive electrode side in the battery, and the same is true This also applies when nickel is used as the positive electrode active material.

  By the way, in an actual alkaline battery, a positive electrode active material, a conductive agent, and an alkaline electrolyte are mixed to form a positive electrode mixture. Further, an alkaline electrolyte injected into a cylindrical separator is used as a positive electrode mixture. Therefore, a certain amount of moisture is contained in the positive electrode mixture after a certain period of time after the battery is assembled (see Patent Document 1). Further, the potassium hydroxide concentration of the electrolytic solution added at the time of forming the positive electrode mixture is desirably 40 to 50 wt%, and the potassium hydroxide concentration of the electrolytic solution injected into the separator is desirably 35 to 45 wt% ( Patent Document 1).

  In addition, regarding the water content in the positive electrode mixture, the moisture content in the positive electrode mixture is set to 3.5% to 5.0%, and the weight of the potassium hydroxide electrolyte contained in the positive electrode mixture after forming the battery Is also proposed to be 10.6 to 15.9 with respect to the solid content weight 100 in the positive electrode mixture (see Patent Document 2). Furthermore, from the viewpoint of safety and discharge characteristics, there is also a proposal that the water addition amount of the entire battery is 0.947 to 1.146 g per 1 AH of theoretical discharge capacity of manganese dioxide (see Patent Document 3). This means that 0.292 to 0.353 g of water is added per 1 g of the active material, which is considerably larger than the amount of water (0.207 g) required for the discharge reaction of 1 g of manganese dioxide. is there.

JP 2002-15748 A (paragraph number 0002, paragraph number 0007) JP 2000-306575 A (paragraph numbers 0006-0007) JP 2001-68121 A (paragraph numbers 0006-0008)

  However, in the range of the amount of electrolyte in the positive electrode mixture, the amount of water is still insufficient, and good characteristics cannot be obtained under heavy load. On the other hand, if the required water content is preliminarily contained in the positive electrode mixture at the time of assembling the battery, the packing density of the active material is lowered and a reduction in capacity cannot be avoided. In addition, moisture may come out from the mixture during molding, or production problems may occur such as the molding strength is reduced and the mixture cannot be molded successfully. Therefore, it is contained in the mixture when forming the positive electrode mixture. It is desirable that the amount of water to be generated is as small as possible.

  That is, while reducing the amount of water in the positive electrode mixture used for battery assembly as much as possible, it is necessary to satisfy the conflicting requirement that a large amount of water be contained in the positive electrode mixture after battery assembly. .

  The present inventors cannot satisfy these requirements only by adjusting the moisture content in the positive electrode mixture or adjusting the amount of water added to the entire battery, and the required amount of moisture after battery assembly. However, it has been found that it is necessary to make some contrivance to enable movement from the separator or negative electrode side into the positive electrode mixture. It has also been found that by properly allocating moisture within the battery, the amount of moisture added to the entire battery can be reduced, and the absence of excess moisture reduces storage degradation at high temperatures.

  The present invention has been made to solve the above problems, and by incorporating a sufficient amount of moisture necessary for the reaction into the positive electrode mixture after battery assembly, load characteristics and safety during short-circuiting and It is an object of the present invention to provide an alkaline battery excellent in high-temperature storage and to provide a method for producing such an alkaline battery.

  The alkaline battery of the present invention is an alkaline battery using a positive electrode mixture containing at least one of manganese dioxide and nickel oxyhydroxide as an active material, wherein the positive electrode mixture after the battery assembly includes potassium hydroxide. The liquid content is contained, and the amount of water contained in the positive electrode mixture is 8.4 to 10 wt% with respect to the weight of the positive electrode mixture including the electrolytic solution.

  Further, the present invention provides an alkaline battery assembling method using a positive electrode mixture containing at least one of manganese dioxide and nickel oxyhydroxide and an alkaline electrolyte in which potassium hydroxide is dissolved. It is a manufacturing method, Comprising: The quantity of the potassium hydroxide contained in the positive mix used for battery assembly shall be 2.4-4 wt% with respect to the weight of the positive mix including electrolyte solution, and after battery assembly Provided is a method for producing an alkaline battery, characterized in that the amount of water contained in the positive electrode mixture is 8.4 to 10 wt% with respect to the weight of the positive electrode mixture including the electrolytic solution.

  Furthermore, the present invention provides an alkaline battery in which an alkaline battery is assembled using a positive electrode mixture containing at least one of manganese dioxide and nickel oxyhydroxide and an alkaline electrolyte in which potassium hydroxide is dissolved, as a method for producing the alkaline battery. The amount of water to be contained in the positive electrode mixture used for battery assembly is 3.0 to 4.2 wt% with respect to the weight of the positive electrode mixture including the electrolyte, and after the battery is assembled The amount of water contained in the positive electrode mixture is 8.4 to 10 wt% with respect to the weight of the positive electrode mixture including the electrolytic solution.

  By assembling the alkaline battery using the above manufacturing method, it becomes possible to contain a sufficient amount of moisture necessary for the discharge reaction in the positive electrode mixture after the battery is assembled. Since the distribution is optimized, it is possible to obtain an alkaline battery that is excellent in load characteristics and safety at the time of a short circuit and has little storage deterioration at high temperatures even if the moisture content of the whole battery is small.

  By optimizing the water content of the positive electrode mixture, the total amount of water in the battery system can be reduced, and the alkaline battery has excellent load characteristics, high safety during short-circuiting, and excellent high-temperature storage characteristics. Can be provided.

  Hereinafter, preparation of the alkaline battery of the present invention will be described. The alkaline battery of the present invention is characterized in that the amount of water contained in the positive electrode mixture is 8.4 to 10 wt% with respect to the weight of the positive electrode mixture including the electrolytic solution after the battery is assembled. Therefore, it is required that a relatively large amount of moisture moves from the separator or the negative electrode side into the positive electrode. In order to cause the movement of moisture, a driving force for that purpose is required. As a method for generating this driving force, for example, an electrolyte solution previously contained in the positive electrode mixture and an injection during assembly An example is a method in which a large difference is provided between the alkaline concentration of the electrolytic solution to be contained or the electrolytic solution to be contained in the negative electrode, and after assembly, moisture on the separator or negative electrode side is moved into the positive electrode mixture by the concentration difference.

  The positive electrode is obtained by mixing at least one of manganese dioxide and nickel oxide, a conductive agent and an alkaline electrolyte containing potassium hydroxide, and molding the mixture to obtain a molded body. By increasing the potassium hydroxide concentration of the alkaline electrolyte to be added at the time of compounding to more than 50 wt%, the driving force is increased and a large amount of water can be taken into the positive electrode mixture. Moreover, since the binding force of the mixture is improved and a homogeneous mixture is formed, the active material can be filled at a high density. At this time, the density of the positive electrode mixture is preferably 3.2 to 3.35 g / cm 3, and a large amount of moisture can be contained while securing a necessary active material filling amount.

  In addition, since manganese dioxide and nickel oxide, which are active materials, usually contain some moisture due to adsorption or the like, the potassium hydroxide concentration of the alkaline electrolyte contained in the mixture is added first. It becomes lower than the potassium hydroxide concentration of the alkaline electrolyte. For this reason, when considering the amount of water, it is better to consider the water derived from the active material, so that the potassium hydroxide concentration of the electrolyte contained in the mixture is finally 40 wt% or more. It is desirable to adjust the concentration of the alkaline electrolyte to be added.

  Further, the addition amount of the alkaline electrolyte is preferably 2.4 to 4 wt% in terms of the weight of potassium hydroxide with respect to the total weight of the mixture including the electrolyte contained in the mixture. It is desirable that the water content be 3.0 to 4.2 wt%. Thereby, an appropriate driving force can be obtained, and it becomes easy to adjust the moisture content after battery assembly to an appropriate range.

  In the preparation of the positive electrode mixture, when the potassium hydroxide concentration of the electrolytic solution is higher than 50 wt%, the saturation solubility of potassium hydroxide at room temperature is exceeded, and therefore, by precipitation of potassium hydroxide exceeding the saturation amount. A heterogeneous mixture is expected. Therefore, it is desirable to increase the saturation amount of potassium hydroxide by mixing the mixture composition in a warm atmosphere, and to produce the positive electrode mixture under conditions such that the electrolyte does not reach the saturation concentration. The temperature condition is preferably 35 ° C. or higher, and preferably 70 ° C. or lower in order to prevent the electrolyte composition from changing due to evaporation of moisture.

  In addition to the above, according to the purpose, a conductive agent, a binder, and the like can be included in the positive electrode mixture. As the conductive agent, carbon materials such as graphite, acetylene black, carbon black, and fibrous carbon can be mainly used. Among them, graphite is preferably used. The addition amount of the conductive agent is desirably 3 or more by weight ratio with respect to the positive electrode active material 100. By containing sufficient moisture in the positive electrode mixture and improving the conductivity of the positive electrode, the reactivity of the active material is increased, and further improvement in load characteristics can be expected. On the other hand, since the reduction of the active material filling amount is not preferable, the ratio of the conductive agent is desirably 8.5 or less.

  As the binder, carboxymethylcellulose, methylcellulose, polyacrylate, polytetrafluoroethylene, polyethylene, or the like can be used.

  In the present invention, it is also possible to expect another effect described below by increasing the reactivity of the positive electrode. If an abnormality such as accidental short-circuiting of the battery occurs, excessive short-circuit current will continue to flow, and the temperature of the battery will rise rapidly due to the heat generated thereby, causing problems such as leakage and battery rupture. . On the other hand, in the battery of the present invention, the discharge reaction at the positive electrode proceeds more rapidly than the conventional battery, and accordingly, the discharge reaction at the negative electrode also proceeds rapidly, and immediately after the occurrence of a short circuit, the discharge product is generated. A large amount is deposited on the negative electrode surface to suppress the discharge reaction. As a result, the short-circuit current is greatly reduced in a short time, and the temperature rise of the battery is suppressed, so that the above problem can be prevented.

  Note that the driving force that causes the movement of moisture to the positive electrode described above is not only determined by the configuration of the positive electrode, but also the relationship with other components such as the negative electrode, in particular, electrolysis separately injected into the exterior body. Since it is closely related to the potassium hydroxide concentration of the electrolytic solution contained in the liquid or the negative electrode mixture, it is desired that the configuration is also optimized. That is, if either one of the injected electrolyte solution or the electrolyte solution contained in the negative electrode mixture, more desirably, the electrolyte solution has a low alkali concentration, the driving force increases, and a more preferable result is obtained. It is done.

  Below, the structure of a negative electrode is demonstrated first. The negative electrode is usually formed as a gel-like mixture in which zinc or zinc alloy powder as an active material, a gelling agent, and an alkaline electrolytic solution in which potassium hydroxide is dissolved are mixed. At this time, the potassium hydroxide concentration of the negative electrode electrolyte is desirably 38 wt% or less. This is because the lower the alkali concentration of the electrolytic solution, the higher the water content, making it easier to adjust the amount of water required for the entire battery. Furthermore, in order to improve the ionic conductivity of the electrolytic solution to increase the reactivity of the negative electrode, to improve the load characteristics and to easily obtain the heat generation suppressing effect at the time of short circuit, the potassium hydroxide concentration is 35 wt% or less, More preferably, it is good to set it as 33.5 wt% or less. On the other hand, the higher the potassium hydroxide concentration, the less the deterioration of characteristics when the battery is stored at a high temperature. Therefore, the potassium hydroxide concentration is preferably 28 wt% or more, more preferably 30 wt% or more.

  In order to cope with a heavy load such as pulse discharge with a large current, it is desired to reduce the particle size of the active material and increase the reaction area. For example, the ratio of the active material powder passing through the 200 mesh sieve is preferably 4 wt% or more, and the load characteristics are remarkably improved by setting the ratio to 15 wt% or more. On the other hand, in order to form a negative electrode mixture that is homogeneous and has good fluidity, it is desirable that the proportion of the fine particles be 40 wt% or less. As described above, when the microparticles are contained at a certain ratio, problems such as gas generation due to a reaction between the active material and the electrolytic solution and a decrease in discharge capacity are likely to occur during storage at a high temperature. In order to prevent this, it is preferable to contain elements such as indium, bismuth and aluminum in zinc. As contents of these elements, it is desirable that indium, bismuth and aluminum are 0.03 to 0.07 wt%, 0.007 to 0.025 wt% and 0.001 to 0.004 wt%, respectively. Further, the problem of heat generation at the time of short circuit becomes more serious as the particle diameter is smaller. However, in the present invention, even when the above fine particles are used, the effect of suppressing heat generation is sufficiently exhibited.

  As a component other than the above, the negative electrode mixture can contain a small amount of an indium compound such as indium oxide and a bismuth compound such as bismuth oxide. When these compounds are contained, gas generation due to the reaction between the zinc alloy powder and the electrolyte can be prevented more effectively, but the load characteristics may be reduced, so the content is determined as necessary. Is done.

  The alkaline battery of the present invention is produced by enclosing the positive electrode mixture and the negative electrode mixture together with a separator in the exterior body. However, since the amount of liquid is insufficient with only the alkaline electrolyte contained in the positive electrode mixture and the negative electrode mixture, a step of injecting another electrolyte into the separator and the positive electrode is usually required. The alkaline electrolyte injected at this time desirably has a potassium hydroxide concentration of 35 wt% or less in order to increase the moisture content and increase the supply of moisture to the positive electrode. Furthermore, from the viewpoint of improvement of load characteristics and suppression of heat generation at the time of short circuit, it is desirable to be 33.5 wt% or less. On the other hand, as the potassium hydroxide concentration is higher, the characteristics deteriorate when the battery is stored at a higher temperature. Therefore, the potassium hydroxide concentration should be 28 wt% or more, more desirably 30 wt% or more.

  In addition, in order to enhance the effect of preventing property deterioration during high-temperature storage, at least one of an electrolytic solution used for forming the positive electrode mixture, an electrolytic solution used for forming the negative electrode mixture, and an electrolytic solution separately injected may contain zinc. It is desirable to contain a compound. As the zinc compound, soluble compounds such as zinc oxide, zinc silicate, zinc titanate, and zinc molybdate can be used, and zinc oxide is particularly preferably used.

  After the battery is assembled, moisture moves from the injected electrolyte solution or the electrolyte solution in the negative electrode mixture to the positive electrode side, and is absorbed by the positive electrode mixture to increase the amount of water in the mixture. This change in the amount of water depends on conditions such as the storage temperature of the battery, so it cannot be said unconditionally, but it will be completed in about 1 to 3 months after the battery is assembled, and thereafter the amount of water in the mixture is constant. It seems to be maintained at the value. In this state, each positive electrode, negative electrode, and each electrolyte used for injection so that the amount of water contained in the positive electrode mixture is 8.4 to 10 wt% with respect to the total weight of the positive electrode mixture including the electrolyte. The composition and the amount added may be adjusted. When the water content is less than 8.4 wt%, a problem occurs in any of load characteristics, heat generation during short circuit, and high temperature storage characteristics. In addition, when the amount is more than 10 wt%, it means that the amount of the electrolyte contained in the positive electrode mixture is excessive, and the conductivity is lowered due to swelling of the mixture, and the amount of electrolyte on the separator side is insufficient. The above problem occurs.

  Moreover, the water content and potassium hydroxide concentration of the electrolyte contained in the positive electrode mixture after battery assembly are obtained by disassembling the battery and analyzing the positive electrode mixture. For example, the moisture content can be determined from the change in weight when the positive electrode mixture is dried in an atmosphere excluding the influence of carbon dioxide gas such as in a vacuum or an inert gas atmosphere, and the potassium hydroxide concentration is From the measured value of the amount of potassium in the solution, the amount of potassium hydroxide can be obtained as it is derived from potassium hydroxide, and can be obtained as (potassium hydroxide amount) / (potassium hydroxide amount + water content). The concentration of potassium hydroxide is preferably 35 to 39.5 wt%, but the electrolyte composition in the positive electrode mixture and the electrolyte composition in the negative electrode mixture at this time are not necessarily the same. In some cases, the moisture transfer to the positive electrode is terminated even when the alkali concentration in the positive electrode mixture is higher, and the state may be maintained as it is.

  In the present invention, as described above, a sufficient amount of moisture is contained in the positive electrode mixture, and the distribution of moisture in the battery is optimized. Therefore, the total amount of moisture in the battery system is reduced as compared with the prior art. Therefore, the amount can be 0.23 to 0.275 g per 1 g of the positive electrode active material. For this reason, excess moisture does not exist in the battery system, and deterioration of characteristics when the battery is stored at high temperature is reduced, but on the other hand, moisture necessary for reaction is ensured, so excellent operating characteristics Can be obtained.

  In the present invention, the shape of the battery is not particularly limited. As an example, when a cylindrical metal outer can is used, a positive electrode mixture formed in a ring shape is disposed inside the outer can, a cup-shaped separator is disposed inside, and an alkaline electrolyte is further added. A battery is assembled by filling the negative electrode mixture after injecting into the inside of the separator and enclosing these components inside the outer can. As shown in FIG. 2, in the cylindrical alkaline battery, when the opening end 1 a of the outer can 1 is folded inward and sealed, the negative electrode terminal plate 207 is prevented from being deformed, and the sealing body 6 In general, a metal washer 9 (a disk-shaped metal plate) is used as an instruction means for supporting the seal from the inside. However, there is a problem that the volume occupied by the sealing portion 10 becomes large.

  On the other hand, in the battery of FIG. 1 in which the metal washer is eliminated and the negative electrode terminal plate 7 is used as an instruction means for supporting the sealing body 6 from the inside, the volume occupied by the sealing portion 10 can be reduced. On the other hand, the filling amount of the mixture can be further increased. However, as the capacity of the battery is increased, the heat generation at the time of short circuit is further increased. However, even in a battery with such a high capacity design, by using the present invention, the abnormal heat generation behavior of the battery can be prevented, so that the practicality of the battery can be enhanced.

  Examples of the present invention will be described below. Of course, the present invention is not limited to these examples.

(Example 1)
87.6 electrolytic manganese dioxide containing 1.6 wt% moisture, graphite, polytetrafluoroethylene powder, and alkaline electrolyte for forming a positive electrode mixture (56 wt% potassium hydroxide aqueous solution containing 2.9 wt% zinc oxide) The mixture was mixed at a weight ratio of 6.7: 0.2: 5.5 at a temperature of 50 ° C. to prepare a positive electrode mixture having a density of 3.21 g / cm 3. In this mixture, the weight ratio of graphite to 100 weight of manganese dioxide was 7.6.

  The potassium hydroxide concentration of the electrolytic solution contained in the positive electrode mixture is 44.6 wt% in consideration of the water content of manganese dioxide, and the amount of potassium hydroxide and the amount of water are the weight of the positive electrode mixture including the electrolytic solution. In contrast, they were 3.1 wt% and 3.7 wt%, respectively.

  Next, alkaline electrolysis for forming zinc alloy powder, polyacrylic acid soda, polyacrylic acid and negative electrode mixture containing 0.05 wt%, 0.05 wt% and 0.005 wt% of indium, bismuth and aluminum, respectively. The liquid (32 wt% potassium hydroxide aqueous solution containing 2.2 wt% of zinc oxide) was mixed at a weight ratio of 39: 0.2: 0.2: 18 to prepare a gelled negative electrode mixture. The zinc alloy powder is a zinc alloy powder having an average particle size of 122 μm, passing through all 80 mesh screens and not passing through 200 mesh screens, and has an apparent density of 2.65 g / cm 3. Met.

  Further, as the exterior body, the sealing portion 10 has a thickness of 0.25 mm, the body portion 20 has a thickness of 0.16 mm, and the positive electrode terminal 1b is prevented from being dented when the battery is dropped. An alkaline battery was fabricated as follows using an exterior can 1 for AA alkaline dry batteries made of killed steel plate, the portion of which was slightly thicker than the barrel portion 20.

  About 11 g of the positive electrode mixture is inserted into the outer can 1 and pressed into a hollow cylinder, and three positive electrode mixture molded bodies having an inner diameter of 9.1 mm, an outer diameter of 13.7 mm, and a height of 13.9 mm; did. 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 non-woven fabric made of acetalized vinylon and tencel having a thickness of 100 μm and a basis weight of 30 g / m 2 is layered in a three-ply shape, wound into a cylindrical shape, the bottom portion is bent, this portion is heat-sealed, and one end is closed. A cup-shaped separator 3 was obtained. This separator 3 is loaded inside the positive electrode 1 inserted in the outer can, and 1.35 g of an alkaline electrolyte for injection (32 wt% potassium hydroxide aqueous solution containing 2.2 wt% zinc oxide) is placed inside the separator. Further, 5.74 g of the negative electrode mixture was filled in the separator 3 to obtain a negative electrode 4. At this time, the total amount of moisture in the battery system was 0.261 g per 1 g of the positive electrode active material.

  After filling the power generation element, the negative electrode current collector rod 5, which is made of brass with a tin plating on the surface and combined with the sealing body 6 made of nylon 6-6, is inserted into the central part of the negative electrode, and the open end of the outer can 1 The AA alkaline battery shown in FIG. 1 was produced by caulking from the outside of 1a by a spinning method. Here, the negative electrode current collector rod 5 used was previously attached by welding to a negative electrode terminal plate 7 made of nickel-plated steel plate having a thickness of 0.4 mm formed by 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.

  With respect to the battery of Example 1 produced as described above, 5 batteries each after 1 month, 3 months, and 6 months from the assembly of the battery were disassembled, and the amount of potassium and moisture contained in the positive electrode mixture Was determined by the following method. The battery after decomposition is divided into a positive electrode and an outer can, and a negative electrode and a separator, and the weight of the positive electrode and the outer can is measured, and this is dried in a vacuum at 110 ° C. for 12 hours. The amount of water contained in the positive electrode mixture was determined from the difference from the weight. Subsequently, the positive electrode mixture after drying was taken out, manganese dioxide was dissolved with an acid, and the weight of potassium was determined by atomic absorption analysis for the solution from which the residue was removed. From the amount of potassium determined in this way, assuming that the atomic weight of potassium is 39.1 and the molecular weight of potassium hydroxide is 56.1, the amount of potassium hydroxide is calculated as the amount of potassium hydroxide = the amount of potassium × (56.1 / 39.1). Further, the concentration of potassium hydroxide is determined for the alkaline electrolyte contained in the positive electrode mixture after battery assembly by the formula of potassium hydroxide concentration = potassium hydroxide amount / (potassium hydroxide amount + water amount). It was.

  Table 1 shows the average value of each battery with respect to the water content and the potassium hydroxide concentration. One month after the assembly of the battery, the required moisture is taken into the positive electrode mixture, and after three months from the assembly, the moisture content does not change and this state is maintained.

(Example 2)
In the same manner as in Example 1, except that 30 wt% potassium hydroxide aqueous solution containing 2.0 wt% of zinc oxide was used as the alkaline electrolyte for forming the negative electrode mixture and the alkaline electrolyte for injection, AA alkaline A battery was produced. At this time, the total amount of moisture in the battery system was 0.268 g per 1 g of the positive electrode active material.

(Example 3)
Containing zinc, indium, bismuth and aluminum in proportions of 0.05 wt%, 0.015 wt% and 0.003 wt%, respectively, as the negative electrode zinc alloy powder, the average particle size is 200 μm, and all 35 mesh sieves pass through; In addition, an AA alkaline battery was manufactured in the same manner as in Example 1 except that a zinc alloy powder having an apparent density of 2.9 g / cm 3 was 6 wt%, and the ratio of those passing through a 200-mesh sieve was 6 wt%. Produced.

Example 4
As the negative electrode zinc alloy powder, the average particle size is 135 μm, all of the 35 mesh sieves pass, and the ratio of those passing through the 200 mesh sieves is 20 wt%, and the apparent density is 2.9 g / cm 3. AA alkaline batteries were produced in the same manner as in Example 1 except that the zinc alloy powder was used.

(Comparative Example 1)
In the same manner as in Example 1, except that a 36 wt% aqueous potassium hydroxide solution containing 2.4 wt% of zinc oxide was used as the alkaline electrolyte for forming the negative electrode mixture and the alkaline electrolyte for injection, the AA alkaline solution was used. A battery was produced. At this time, the total amount of moisture in the battery system was 0.247 g per 1 g of the positive electrode active material.

(Comparative Example 2)
An AA alkaline battery was produced in the same manner as in Example 1 except that a 42 wt% potassium hydroxide aqueous solution containing 2.9 wt% of zinc oxide was used as the alkaline electrolyte for forming the positive electrode mixture. In this battery, the potassium hydroxide concentration of the electrolyte solution contained in the positive electrode mixture before battery assembly is 33.5 wt% in consideration of the moisture content of manganese dioxide, and the potassium hydroxide amount and moisture amount include the electrolyte solution. Further, they were 2.3 wt% and 4.4 wt%, respectively, with respect to the weight of the mixture. The total amount of water in the battery system was 0.270 g per 1 g of the positive electrode active material.

  For each of the five batteries of Example 2, Comparative Example 1 and Comparative Example 2, the amount of water contained in the positive electrode mixture after 3 months from the assembly and the positive electrode mixture were the same as in Example 1. The potassium hydroxide concentration of the alkaline electrolyte contained was determined. These results and the results of the battery of Example 1 are shown in Table 2 together with the total amount of water in the battery system (however, converted per 1 g of the positive electrode active material).

  In addition, about the battery of Example 3 and Example 4, although only the moisture content which the positive mix contained was measured, since the result similar to Example 1 was obtained, it was not shown in Table 2.

  As shown in Table 2, in the batteries of Examples 1 and 2, the amount of water contained in the positive electrode mixture was in the range of 8.4 to 10 wt%, and a sufficient amount of water for the reaction of the positive electrode active material was provided. It could be contained in the positive electrode mixture. Moreover, the potassium hydroxide concentration of the electrolytic solution contained in the positive electrode mixture could be within a desirable range of 35 to 39.5 wt%.

  Next, for the batteries of Examples 1 to 4 and Comparative Examples 1 to 2, the load characteristics, the battery temperature at the time of short circuit, and the high temperature storage characteristics were measured as follows.

  As for the load characteristics, a base discharge current is set to 0.5 A, and a pulse discharge test is performed in which a 2 A pulse current is passed for 2 seconds at 30 second intervals. The number of pulse discharges required for the evaluation was evaluated.

  The battery temperature at the time of short-circuit is measured by measuring the temperature of the outer can after fixing the thermocouple with aluminum tape at the center of the side of the outer can of the battery and shorting the battery. evaluated. In addition, about the battery of Example 2 and Comparative Example 1, not only the outer can surface temperature but also the time change of the short circuit current was measured.

  For high temperature storage characteristics, the change in discharge capacity before and after storage in high temperature storage was examined, and the degree of characteristic deterioration was evaluated by the capacity retention rate. That is, the battery was discharged at a discharge current of 1 A, the discharge capacity until the battery voltage reached 0.9 V was measured, and this was defined as the discharge capacity before storage. Also, a battery other than the above battery is stored in a constant temperature bath at 60 ° C. for 20 days, taken out, cooled at room temperature for 1 day, and then discharged at a discharge current of 1 A until the battery voltage reaches 0.9V. The discharge capacity was measured as the discharge capacity after storage, the ratio of the discharge capacity after storage to the discharge capacity before storage was determined, and this was used as the capacity retention to evaluate the high-temperature storage characteristics.

  Table 3 summarizes the measurement results of the number of pulse discharges, the maximum temperature of the outer can surface, and the capacity retention. Further, the time variation of the outer can surface temperature and the short-circuit current of the batteries of Example 2 and Comparative Example 1 are shown in FIG. 3 for the battery of Example 2 and FIG. 4 for the battery of Comparative Example 1.

  In the batteries of Examples 1 to 4 of the present invention, the total water content in the battery system is 0.23 to 1 g of the positive electrode active material by setting the water content of the positive electrode mixture to 8.4 to 10 wt%. Despite being reduced to 0.275 g, the load characteristics were excellent, the heat generation at the time of short-circuiting of the battery was suppressed, and the characteristic deterioration during high-temperature storage was small. In particular, in the battery of Example 3, which contains 6 wt% of a powder of 200 mesh or less in the zinc alloy powder and the ratio of fine particles is larger than that of Example 1, the content ratio of indium, bismuth and aluminum is optimized. Thus, the load characteristics could be improved as compared with the battery of Example 1 without causing an increase in temperature or a decrease in capacity retention rate due to excessive heat generation. Further, in the battery of Example 4 in which the proportion of fine particles was further increased from that of Example 3, the load characteristic could be further increased while maintaining excellent high-temperature storage characteristics, although the battery temperature slightly increased. It was.

  On the other hand, in the batteries of Comparative Examples 1 and 2 in which the water content of the positive electrode mixture did not reach the above range, the heat generation at the time of short circuit was large and the battery temperature was significantly increased, or the high temperature storage characteristics were deteriorated. It did not become a practical characteristic. Regarding the temperature rise at the time of short circuit, as shown in FIG. 3 and FIG. 4, the battery of the present invention generates less heat because the short circuit current decreases in a short time, and the temperature rise of the battery is small. It can be seen that the current decrease was slow, the heat generation increased, and the battery temperature increased significantly.

It is sectional drawing which shows the whole structure of the alkaline battery using a negative electrode terminal board as an instruction | indication means which supports a sealing body from the inside. It is sectional drawing which shows the general structure of the conventional alkaline battery. It is a graph which shows the change of short circuit current and armored can surface temperature when the alkaline battery of Example 2 of the present invention is short-circuited. It is a graph which shows the change of a short circuit current and the armored can surface temperature when the alkaline battery of the comparative example 1 of this invention is short-circuited.

Explanation of symbols

1 Exterior can
1a Open end of outer can
2 Positive electrode
3 Separator
4 Negative electrode
5 Negative current collector
6 Sealing body
7,207 Negative terminal plate
8 Insulation plate
9 Metal washer
10 Sealing part
20 trunk

Claims (15)

  An alkaline battery using a positive electrode mixture containing at least one of manganese dioxide and nickel oxyhydroxide as an active material, wherein the positive electrode mixture after battery assembly contains an alkaline electrolyte containing potassium hydroxide, An alkaline battery characterized in that the water content of the mixture is 8.4 to 10 wt% with respect to the weight of the positive electrode mixture including the electrolyte.   The alkaline battery according to claim 1, wherein the density of the positive electrode mixture before battery assembly is 3.2 to 3.35 g / cm 3.   The alkaline battery according to claim 1 or 2, wherein the potassium hydroxide concentration of the alkaline electrolyte contained in the positive electrode mixture before battery assembly is 40 wt% or more.   4. The alkaline battery according to claim 1, wherein the total amount of water in the battery system is 0.23 to 0.275 g per 1 g of the positive electrode active material.   The alkaline electrolyte contained in the positive electrode mixture after battery assembly has a potassium hydroxide concentration of 35 to 39.5 wt% determined from the amount of potassium and the amount of water. The alkaline battery described in 1.   6. The alkaline battery according to claim 1, wherein the alkaline electrolyte contains a zinc compound.   The alkaline battery according to any one of claims 1 to 6, wherein the proportion of zinc alloy powder that uses zinc alloy powder as a negative electrode active material and passes through a 200-mesh sieve is 4 to 40 wt%.   The alkaline battery according to claim 7, wherein the zinc alloy powder contains indium, bismuth, and aluminum.   The content of indium, bismuth and aluminum is 0.03 to 0.07 wt%, 0.007 to 0.025 wt% and 0.001 to 0.004 wt%, respectively. Alkaline battery.   An alkaline battery manufacturing method for assembling an alkaline battery using a positive electrode mixture containing at least one of manganese dioxide and nickel oxyhydroxide and an alkaline electrolyte in which potassium hydroxide is dissolved. The amount of potassium hydroxide contained in the agent is 2.4 to 4 wt% with respect to the weight of the positive electrode mixture including the electrolytic solution, and the amount of water contained in the positive electrode mixture after battery assembly is changed to The manufacturing method of the alkaline battery characterized by setting it as 8.4-10 wt% with respect to the weight of the positive electrode mixture included.   An alkaline battery manufacturing method for assembling an alkaline battery using a positive electrode mixture containing at least one of manganese dioxide and nickel oxyhydroxide and an alkaline electrolyte in which potassium hydroxide is dissolved. The amount of water to be contained in the agent is set to 3.0 to 4.2 wt% with respect to the weight of the positive electrode mixture including the electrolytic solution, and the amount of water contained in the positive electrode mixture after battery assembly is changed to the electrolytic solution. The manufacturing method of the alkaline battery characterized by setting it as 8.4-10 wt% with respect to the weight of the positive electrode mixture included.   The method for producing an alkaline battery according to claim 10 or 11, wherein the potassium hydroxide concentration of the alkaline electrolyte contained in the positive electrode mixture before assembling the battery is 40 wt% or more.   The alkaline electrolyte contained in the positive electrode mixture after battery assembly has a potassium hydroxide concentration determined from the amount of potassium and the amount of water of 35 to 39.5 wt%. The manufacturing method of the alkaline battery as described in any one of.   The method for producing an alkaline battery according to any one of claims 10 to 13, wherein the total amount of water in the battery system is 0.23 to 0.275 g per g of the positive electrode active material. The method for producing an alkaline battery according to claim 10, wherein the positive electrode mixture is formed at a temperature of 35 to 70 ° C.

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