JP2006221831A - Alkaline dry cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to alleviate a phenomenon that voltage reduction at the cycle end stage becomes large in the case of repeating a pulse discharge of high load, and enable an equipment to be operated stably in an alkaline dry cell in which nickel oxyhydroxide is added to a positive electrode mixture. <P>SOLUTION: This is the alkaline dry cell which is provided with a positive electrode to contain nickel oxyhydroxide and manganese dioxide, a gelatinous negative electrode in which zinc is made an active material, and an alkaline electrolytic solution, and in which the alkaline electrolytic solution is KOH aqueous solution added with LiOH. Especially, the zinc is a zinc alloy to contain at least aluminum, and an aluminum compound is preferably contained in the alkaline electrolytic solution together with LiOH. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an alkaline dry battery (so-called nickel manganese battery) that includes nickel oxyhydroxide as an active material in a positive electrode mixture and adopts an inside-out structure.

  An alkaline battery is an inside-out in which a cylindrical manganese dioxide positive electrode mixture pellet is placed in close contact with the positive electrode case in a positive electrode case that also serves as a positive electrode terminal, and a gelatinous zinc negative electrode is placed in the center via a separator. Has a mold structure. With the spread of digital devices in recent years, the load power of devices using these batteries has gradually increased, and batteries having excellent high load discharge performance have been desired. In order to cope with this, Patent Document 1 and the like have proposed that nickel oxyhydroxide is mixed with the positive electrode mixture to form a battery having excellent high-load discharge characteristics. In recent years, such nickel oxyhydroxide is proposed. Alkaline dry batteries that contain lithium in the positive electrode mixture have been put into practical use and have come into widespread use.

  Here, the nickel oxyhydroxide used in the alkaline dry battery described above is a spherical or egg-shaped nickel hydroxide that has been used for alkaline storage battery applications as in Patent Document 2 with an oxidizing agent such as an aqueous sodium hypochlorite solution. It is common to use an oxidized one. At this time, the spherical nickel hydroxide used is a β-type having a large bulk density (tap density), and this is converted into a β-type spherical nickel oxyhydroxide by oxidant treatment, so that high filling into the battery is achieved. Oriented.

On the other hand, in many cases, the negative electrode is made of zinc alloy powder containing a small amount of aluminum, bismuth, indium or the like known in Patent Document 3 as in the case of the alkaline manganese dry battery, sodium polyacrylate as a gelling agent, In many cases, a gelled negative electrode prepared by mixing with an alkaline electrolyte is used. Here, from the viewpoint of improving the corrosion resistance of the zinc negative electrode, many studies have been made on various zinc alloy compositions, particle size optimization (for example, Patent Document 4), and various additives (for example, Patent Document 5). Further, although there are few studies on the electrolytic solution, in Patent Document 6, lithium hydroxide is contained in the gelled negative electrode in a proportion of 0.1% by weight to 1% by weight (although it is used for an air battery) to improve the corrosion resistance. It has been proposed.
JP-A-57-72266 Japanese Patent Publication No. 4-80513 JP 5-166507 A JP 2002-270164 A Japanese Patent No. 3006269 JP 2000-82503 A

  The nickel oxyhydroxide-containing alkaline dry battery as described above is excellent in high load characteristics as compared with a normal alkaline dry battery, but the characteristics are still not perfect. In particular, in an application that repeats pulse discharge in a high load region such as a digital still camera, the degree of voltage drop during discharge increases as the number of pulses increases. For this reason, it is easy to generate the problem that the battery remaining amount display attached to the device does not function well or the device in use suddenly stops.

  As an example, FIG. 3 shows the result (discharge curve) of a pulse discharge test assuming a digital still camera with an existing nickel oxyhydroxide-containing alkaline battery. In this test, a cycle of discharging a battery (1 cell) at a constant power of 650 mW for 28 seconds in a 20 ° C. atmosphere and then discharging for 2 seconds at a constant power of 1500 mW was continuously repeated. The state where the power is turned on and the liquid crystal monitor or the like is driven, and the discharge of 1500 mW simulates the state where the flash photography of the camera was performed.

  From FIG. 3, the voltage drop at the time of 1500 mW pulse discharge is about 80 mV at the beginning of the cycle, whereas when the cycle is repeated, the voltage drop increases to about 300 mV. With this behavior, the display of the remaining battery level attached to the device at the end of the cycle (mainly detecting the battery voltage during 650 mW discharge and the battery voltage in the open state) is high. On the other hand, when 1500 mW discharge (camera shooting) is performed, the battery voltage becomes equal to or lower than the cut voltage of the device, causing a phenomenon that the device suddenly stops. That is, it is important here that the voltage drop during 1500 mW discharge does not increase from the beginning to the end of the pulse discharge cycle.

  In view of the problems as described above, the present invention includes a positive electrode containing nickel oxyhydroxide and manganese dioxide, a gelled negative electrode using zinc as an active material, and an alkaline electrolyte, and the alkaline electrolyte includes KOH to which LiOH is added. An alkaline battery characterized by being an aqueous solution.

  In the alkaline dry battery of the present invention, the degree of polarization of both the positive electrode and the negative electrode during pulse discharge is greatly reduced, particularly at the end of the discharge cycle, due to the effect of LiOH added to the alkaline electrolyte. For this reason, it is possible to mitigate the phenomenon that the voltage drop during pulse discharge becomes large when high-load pulse discharge is repeated.

Here, it is presumed that the degree of polarization of the positive electrode is reduced because Li ⁺ is taken into the nickel oxyhydroxide crystal, the lattice defect concentration is increased, and the ionic conductivity is increased. The reason why the degree of polarization of the negative electrode is reduced is thought to be that Li ⁺ is taken into the oxide film formed on the surface of the zinc alloy with discharge, and the ionic conductivity of the film is increased.

  According to the present invention, when a high load pulse discharge is repeated in a nickel oxyhydroxide-containing alkaline battery, the phenomenon that the voltage drop at the end of the pulse discharge cycle is increased can be alleviated. Therefore, it is possible to avoid the problems such as the battery remaining amount display attached to the device (such as a digital still camera) not functioning well or the device being used suddenly stops as described above.

  The present invention includes a positive electrode containing nickel oxyhydroxide and manganese dioxide, a gelled negative electrode using zinc as an active material, and an alkaline electrolyte, and the alkaline electrolyte is a KOH aqueous solution to which LiOH is added. It is an alkaline battery.

  Here, about the ratio of the nickel oxyhydroxide in a positive mix, the range of 10 to 80 weight% is suitable with respect to the whole positive mix. When comparing manganese dioxide and nickel oxyhydroxide, manganese dioxide is superior in terms of capacity per unit weight (mAh / g), filling property in the case, and material price. For load discharge characteristics, nickel oxyhydroxide is superior. Considering the balance of characteristics and price as a whole battery, it is most preferable to set the mixing ratio of nickel oxyhydroxide in the positive electrode mixture within the above range.

  Furthermore, the amount of LiOH contained in the total amount of the alkaline electrolyte (including the electrolyte in the gelled negative electrode and the positive electrode mixture) is preferably in the range of 0.1 to 2% by weight. Regarding the amount of LiOH in the alkaline electrolyte, if the amount of LiOH is less than 0.1% by weight of the total amount of the alkaline electrolyte, the effect of reducing the polarization of the positive and negative electrodes is lowered. On the other hand, when the LiOH amount exceeds 2% by weight of the total amount of the alkaline electrolyte, the electrical conductivity of the electrolyte is lowered. Therefore, it is preferable that the amount of LiOH contained in the total amount of the alkaline electrolyte is in the range of 0.1 to 2% by weight because the degree of polarization of both the positive electrode and the negative electrode can be more effectively reduced.

  The present invention also includes a positive electrode containing nickel oxyhydroxide and manganese dioxide, a gelled negative electrode using at least a zinc alloy containing aluminum as an active material, and an alkaline electrolyte, wherein the alkaline electrolyte is added with LiOH and an aluminum compound. It is an alkaline dry battery characterized by being a KOH aqueous solution.

  Aluminum in the zinc alloy has the effect of smoothing the alloy surface and improving the corrosion resistance. Therefore, in consideration of the storage characteristics (storability) of a practical alkaline battery, it is preferable to use a zinc alloy containing at least aluminum. Then, although the detailed mechanism is not known, such a zinc alloy containing aluminum is used as a negative electrode, and KOH in which LiOH and an aluminum compound (aluminum hydroxide, aluminum oxide, etc.) are added to an alkaline electrolyte. When the aqueous solution is used, the storage characteristics of the battery can be greatly enhanced while sufficiently obtaining the improvement effect of the high-load pulse discharge as described above.

  At this time, the ratio of nickel oxyhydroxide in the positive electrode mixture is preferably in the range of 10 to 80% by weight with respect to the whole positive electrode mixture. When comparing manganese dioxide and nickel oxyhydroxide, manganese dioxide is superior in terms of capacity per unit weight (mAh / g), filling property in the case, and material price. For load discharge characteristics, nickel oxyhydroxide is superior. Considering the balance of characteristics and price as the whole battery, it is more preferable that the ratio of nickel oxyhydroxide in the positive electrode mixture is 10 to 80% by weight with respect to the whole positive electrode mixture.

  Furthermore, the amount of LiOH and aluminum compound contained in the total amount of the alkaline electrolyte (including the electrolyte in the gelled negative electrode and the positive electrode mixture) is 0.1 to 2% by weight and 0.01 to 2% by weight, respectively. It is suitable to be in the range. This is because the amount of aluminum compound (aluminum hydroxide, aluminum oxide, etc.) is less than 0.01% by weight of the total amount of the alkaline electrolyte, and the effect of suppressing storage deterioration is reduced. This is because if the amount of the compound exceeds 2% by weight, adverse effects such as a decrease in the conductivity of the electrolytic solution after storage of the battery are likely to occur. Therefore, the amount of the aluminum compound contained in the alkaline electrolytic solution is less than the total amount of the alkaline electrolytic solution. It is more preferable to set the content in the range of 0.01 to 2% by weight from the viewpoint of improving the characteristics of the battery for the first time and after storage.

  Examples of the present invention will be described in detail below.

Example 1
(Production of nickel oxyhydroxide)
In a reaction vessel equipped with a stirring blade, a mixed aqueous solution of nickel sulfate (II), zinc (II) sulfate, cobalt (II) sulfate, an aqueous sodium hydroxide solution, and aqueous ammonia at a predetermined charging ratio are set to a constant pH in the vessel. As a result, a fixed amount was supplied with a pump and nickel hydroxide in which a small amount of zinc / cobalt was dissolved was precipitated and grown by continuing sufficient stirring. Subsequently, the obtained particles were heated in a sodium hydroxide aqueous solution different from the above to remove sulfate radicals, then washed with water and vacuum dried to produce raw material nickel hydroxide (composition: Ni _0.95 Zn _0.03 Co _0.02 ( OH) ₂ ). It was confirmed by powder X-ray diffraction measurement that the raw material nickel hydroxide thus prepared had a β-type crystal structure.

Next, 200 g of the above nickel hydroxide was put into 1 L of a 0.1 mol / L sodium hydroxide aqueous solution, and a sufficient amount of an oxidizing agent sodium hypochlorite aqueous solution (effective chlorine concentration: 10 wt%) was added and stirred. To nickel oxyhydroxide. The obtained particles were sufficiently washed with water and then vacuum dried at 60 ° C. (24 hours). This nickel oxyhydroxide had a β-type crystal structure, had a volume-based average particle size of 10 μm, a tap density (300 times) of 2.35 g / cm ³ , and a BET specific surface area of 14 m ² / g.

(Preparation of alkaline battery)
An alkaline battery was prepared using the above nickel oxyhydroxide powder. FIG. 1 is a front view, partly in section, of an alkaline battery used in the present invention. The positive electrode case 1 is made of a nickel-plated steel plate. A graphite coating film 2 is formed inside the positive electrode case 1. A plurality of short cylindrical positive electrode mixture pellets 3 containing manganese dioxide and nickel oxyhydroxide as main components are inserted into the positive electrode case 1 and are re-pressurized in the case to be brought into close contact with the inner surface of the case 1. . Then, after the separator 4 and the insulating cap 5 are inserted inside the positive electrode mixture pellet 3, an electrolytic solution is injected for the purpose of wetting the separator 4 and the positive electrode mixture pellet 3. For example, a 40 wt% potassium hydroxide aqueous solution is used as the electrolytic solution. After the injection, the gelled negative electrode 6 is filled inside the separator 4. The gelled negative electrode 6 is made of, for example, sodium polyacrylate as a gelling agent, an alkaline electrolyte, and zinc powder as a negative electrode active material. Next, the negative electrode current collector 10 integrated with the resin sealing plate 7, the bottom plate 8 also serving as the negative electrode terminal, and the insulating washer 9 is inserted into the gelled negative electrode 6. Then, the opening end of the positive electrode case 1 is caulked to the peripheral portion of the bottom plate 8 via the end portion of the sealing plate 7, and the opening of the positive electrode case 1 is brought into close contact. Next, the outer label 11 is coated on the outer surface of the positive electrode case 1. An alkaline battery is thus completed.

  In this example, first, electrolytic manganese dioxide, nickel oxyhydroxide prepared as described above, and graphite are blended at a weight ratio of 50: 45: 5, and 1 part by weight of the electrolyte is mixed with 100 parts by weight of the mixed powder. After that, the mixture was uniformly stirred and mixed with a mixer to adjust the particle size. The obtained granular material is pressure-molded into a hollow cylindrical shape to form a positive electrode mixture, and after inserting a separator, an electrolyte solution is injected and a gelled negative electrode (using pure zinc powder as an active material) is filled. Then, an AA size alkaline dry battery (battery 1) shown in FIG. 1 was assembled. In this battery 1, an alkaline solution composed of 36% by weight KOH and 1% by weight LiOH is used for any of the electrolytic solution contained in the positive electrode mixture, the electrolytic solution injected into the separator, and the electrolytic solution contained in the gelled zinc negative electrode. An aqueous solution was used.

  In addition, the electrolytic solution to be included in the positive electrode mixture, the electrolytic solution to be poured into the separator, and the electrolytic solution to be included in the gelled zinc negative electrode are all 37% by weight KOH single aqueous solution. Battery 2 was produced.

(Battery evaluation)
About the battery 1 and the battery 2 (the initial state) produced above, a cycle of discharging at a constant power of 650 mW for 28 seconds in an atmosphere at 20 ° C. and then performing pulse discharge for 2 seconds at a constant power of 1500 mW is performed by 1500 mW pulse discharge. The process was repeated until the lower limit voltage of 1.05 V was reached. This discharge pattern is intended for use with a digital still camera, and simulates a state in which a 650 mW discharge turns on the camera and drives a liquid crystal monitor or the like, and a 1500 mW discharge performs flash photography of the camera. . The discharge curves obtained here are shown in FIG. 2 (Battery 1) and FIG. 3 (Battery 2). The number of pulse discharge cycles and the voltage drop amount of 1500 mW pulse discharge at the 1st cycle and the final cycle (1.05V reached). Table 1 summarizes (also shown in FIGS. 2 and 3).

  The battery 1 in which LiOH is added to the electrolytic solution has a larger number of cycles to reach 1.05 V than the battery 2 that does not contain LiOH in the electrolytic solution, and the voltage drop amount of pulse discharge at the final cycle (end of discharge) is larger. I understand that there are few. This corresponds to the fact that in actual digital still camera applications, the number of possible shots per battery is large, and the problem that the device suddenly stops during use is unlikely to occur.

  In order to qualitatively interpret the above phenomenon, a hole is formed in a part of the positive electrode case of each of the first battery 1 and the battery 2, and a liquid bridge is formed at the mercury / mercury oxide reference electrode outside the battery through a salt bridge. The potential change of the positive electrode and the negative electrode during the discharge cycle was measured. The obtained potential curve is shown in FIG. 4 (battery 1) and FIG. 5 (battery 2). In the battery 1, the degree of polarization of the positive electrode and the negative electrode at the end of the cycle is lower than that in the battery 2, and it can be confirmed that the characteristics are improved by both effects.

The reduction in the degree of polarization of the positive electrode and the negative electrode is due to the interaction between both active materials and LiOH added to the electrolyte. The reason for the decrease in the degree of polarization of the positive electrode is presumed to be that Li ⁺ is incorporated into the nickel oxyhydroxide crystal, the lattice defect concentration increases, and the ionic conductivity increases. The reason why the degree of polarization of the negative electrode is reduced is thought to be that Li ⁺ is taken into the oxide film formed on the surface of the zinc alloy with discharge, and the ionic conductivity of the film is increased.

(Example 2)
Here, the compounding ratio of manganese dioxide and nickel oxyhydroxide in the positive electrode mixture was examined. Electrolytic manganese dioxide, nickel oxyhydroxide prepared in Example 1 and graphite were mixed at a weight ratio as shown in Table 2, and 1 part by weight of the electrolyte was mixed with 100 parts by weight of the mixed powder. The mixture was uniformly stirred and mixed to adjust the particle size to a constant particle size. The obtained granular material is pressure-molded into a hollow cylindrical shape to form a positive electrode mixture, and after inserting a separator, an electrolyte solution is injected and a gelled negative electrode (using pure zinc powder as an active material) is filled. AA size alkaline batteries (battery X1 to battery X10) corresponding to each positive electrode mixture were assembled. In each of the batteries X1 to X10, the electrolyte solution to be included in the positive electrode mixture, the electrolyte solution to be injected into the separator, and the electrolyte solution to be included in the gelled zinc negative electrode were each 36% by weight KOH and 1% by weight. An alkaline aqueous solution made of LiOH was used.

  In the same manner as in Example 1, the 10 types of batteries thus prepared (initial state) were discharged at 20 ° C. with a constant power of 650 mW for 28 seconds and then pulse-discharged with a constant power of 1500 mW for 2 seconds. The cycle was repeated until the lower limit voltage of 1500 mW pulse discharge reached 1.05V. In consideration of uses other than digital still cameras, the battery was continuously discharged at a constant current of 100 mA (low load) at 20 ° C., and the discharge capacity until the battery voltage reached 0.9 V was measured. Table 2 shows the obtained results (regarding 100 mA discharge, the discharge capacity of the battery X5 is normalized to 100).

  When the ratio of nickel oxyhydroxide in the positive electrode mixture is larger than 80% by weight (battery X9, battery X10), it is better than a battery not containing LiOH in the electrolyte (battery 2 in Example 1). Although giving pulse characteristics, the discharge capacity of 100 mA (low load) is significantly lower than that of the batteries X1 to X8. On the other hand, when the ratio of nickel oxyhydroxide is less than 10% by weight (battery X1), it is better than the battery not containing LiOH in the electrolyte (battery 2 in Example 1), but more than batteries X2 to X10. It can be seen that the pulse discharge cycle characteristics are greatly reduced. From this result, it is presumed that in the present invention, the ratio of nickel oxyhydroxide in the positive electrode mixture is preferably 10 to 80% by weight.

(Example 3)
Subsequently, the amount of LiOH added to the electrolytic solution was examined. Alkaline electrolytes y1 to y12 composed of KOH and LiOH having the composition shown in Table 3 were prepared, and at the same time, 12 types of gelled negative electrodes using these respectively (using pure zinc powder as an active material) Also made.

  Electrolytic manganese dioxide, nickel oxyhydroxide prepared in Example 1 and graphite were mixed at a weight ratio of 50: 45: 5, and after mixing 1 part by weight of electrolyte Y1 with 100 parts by weight of the mixed powder, The mixture was uniformly stirred and mixed with a mixer to regulate the particle size. The obtained granular material is pressure-molded into a hollow cylindrical shape to form a positive electrode mixture, and after inserting a separator, an electrolyte y1 injection and a gelled negative electrode (corresponding to the electrolyte y1) are filled. AA size alkaline batteries (battery Y1) were assembled.

  In addition, in the above description, all of the electrolytic solution to be included in the positive electrode mixture, the electrolytic solution to be injected into the separator, and the electrolytic solution to be included in the gelled zinc negative electrode are changed from the electrolytic solution y1 to the electrolytic solution y2, and the others are exactly the same. A three-size alkaline battery (battery Y2) was produced. Thereafter, the electrolytic solution composition was changed in the same manner as the electrolytic solution y3 to the electrolytic solution y12, and alkaline batteries (batteries Y3 to Y12) corresponding to the respective electrolytic solutions were produced.

  In the same manner as in Example 1, the 12 types of batteries thus produced (initial state) were discharged at 20 ° C. for 28 seconds with a constant power of 650 mW and then pulse-discharged for 2 seconds with a constant power of 1500 mW. The cycle was repeated until the lower limit voltage of 1500 mW pulse discharge reached 1.05V. The obtained results are shown in Table 3.

  When LiOH in the electrolytic solution is less than 0.1% by weight (batteries Y1, Y7), or when LiOH in the electrolytic solution is larger than 2% by weight (batteries Y6, Y12), LiOH is added to the electrolytic solution. Although it is better than the battery 2 that does not contain, it can be seen that the effect of improving the pulse discharge cycle characteristics is not sufficiently obtained. If the amount of LiOH is less than 0.1% by weight, the absolute amount is too small, and thus the degree of effect is small. If the amount of LiOH is more than 2% by weight, the electrical conductivity of the electrolytic solution is lowered. It is presumed that it happened. From this result, it is presumed that in the present invention, the amount of LiOH in the electrolytic solution is more preferably in the range of 0.1 to 2% by weight.

Example 4
Here, the kind of zinc powder used for the negative electrode and the additive (aluminum hydroxide) in the negative electrode gel were examined. As zinc powder, three kinds of Zn (c) containing pure Zn (a), Zn (b) containing 35 ppm of Al, 35 ppm of Al, 200 ppm of Bi, and 300 ppm of In were prepared by a gas atomizing method. The particle size distribution and the BET specific surface area of these zinc powder a to zinc powder c were adjusted to be approximately the same.

  In producing the battery, the electrolyte solution (1) contained in the positive electrode mixture, the electrolyte solution (2) injected into the separator, and the gelled zinc negative electrode (3) were changed in the combinations shown in Table 4. Electrolytic manganese dioxide, nickel oxyhydroxide prepared in Example 1 and graphite were mixed at a weight ratio of 50: 45: 5, and 1 part by weight of the electrolytic solution (1) was 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. The obtained granular material was pressure-molded into a hollow cylindrical shape to form a positive electrode mixture, and after inserting the separator, the electrolyte solution (2) was injected and the gelled negative electrode (3) was filled. AA size alkaline batteries (battery A1 to battery A3, battery B1 to battery B3, battery C1 to battery C3) corresponding to the combinations were assembled. In addition, in the battery A3, the battery B3, and the battery C3, the amount of aluminum hydroxide added to the gelled negative electrode is equal to the total weight of the electrolyte solution in (1-3) (that is, all electrolyte solutions contained in the battery). On the other hand, the content was 1% by weight.

  In the same manner as in Example 1, the nine types of batteries thus manufactured (initial state) were discharged for 28 seconds at a constant power of 650 mW in a 20 ° C. atmosphere, and then pulse-discharged for 2 seconds at a constant power of 1500 mW. The cycle was repeated until the lower limit voltage of 1500 mW pulse discharge reached 1.05V. In consideration of the storage characteristics (storability) of practical alkaline batteries, these nine batteries are stored in a 45 ° C. atmosphere for one month, and the same pulse discharge cycle test is performed on the subsequent batteries. went. The results are summarized in Table 5.

In the first battery, regardless of the type of zinc powder, almost the same high characteristics can be obtained by adding LiOH to the electrolyte (battery A2, battery A3, battery B2, battery B3, battery C2, battery C3). . As described in Example 1, this is due to the interaction between the positive and negative electrode active materials and LiOH added to the electrolytic solution. The reason for the decrease in the degree of polarization of the positive electrode is presumed to be that Li ⁺ is incorporated into the nickel oxyhydroxide crystal, the lattice defect concentration increases, and the ionic conductivity increases. The reason why the degree of polarization of the negative electrode is reduced is thought to be that Li ⁺ is taken into the oxide film formed on the surface of the zinc alloy with discharge, and the ionic conductivity of the film is increased.

  Moreover, in the battery after storage, the zinc powder containing Al is the highest in the system (battery B3, battery C3) in which aluminum hydroxide is also added to the gelled negative electrode, and the zinc powder does not contain Al. In a system using B2 (battery A2, battery A3), a system in which aluminum hydroxide is not added to the gelled negative electrode (battery B2, battery C2), or a system not containing LiOH in the electrolyte (battery B1, battery C1) There is little suppression of deterioration. And the characteristic fall of the system (battery A1) which does not contain any said addition becomes the most remarkable.

  Here, the characteristics of the battery B3 and the battery C3 are maintained high because the aluminum in the zinc alloy smoothes the surface of the alloy and the surface of the zinc alloy has an Al-containing oxide derived from aluminum hydroxide. This seems to be due to the fact that the corrosion resistance of the zinc powder during storage was maximized in combination with the formation of a good quality protective film.

  Thus, taking into account the maintenance of the pulse discharge cycle characteristics after storage, in the present invention, a zinc alloy containing at least aluminum is used for the negative electrode, and LiOH and an aluminum compound (such as aluminum hydroxide) are used for the alkaline electrolyte. It is most preferable to use a KOH aqueous solution to which is added).

(Example 5)
Here, in the battery using the zinc alloy containing aluminum and the KOH aqueous solution to which LiOH and aluminum hydroxide were added, the mixing ratio of manganese dioxide and nickel oxyhydroxide in the positive electrode mixture was examined.

  Electrolytic manganese dioxide, nickel oxyhydroxide prepared in Example 1 and graphite were mixed at a weight ratio as shown in Table 6, and 1 part by weight of the electrolyte was mixed with 100 parts by weight of the mixed powder. The mixture was uniformly stirred and mixed to adjust the particle size to a constant particle size. The obtained granular material is pressure-molded into a hollow cylindrical shape to form a positive electrode mixture, a separator is inserted, an electrolyte solution is injected, and a gelled negative electrode (Zn containing 35 ppm of Al is used as an active material) is filled. AA size alkaline dry batteries (battery Z1 to battery Z10) corresponding to each positive electrode mixture were assembled. In addition, alkaline solution which consists of 36 weight% KOH and 1 weight% LiOH about all of the electrolyte solution included in a positive electrode mixture, the electrolyte solution poured into a separator, and the electrolyte solution included in a gel-like zinc negative electrode here. And aluminum hydroxide corresponding to 1% by weight with respect to the total amount of the electrolyte contained in the battery was added to the gelled zinc negative electrode.

  The 10 types of batteries thus prepared (initial state) were discharged for 28 seconds at a constant power of 650 mW in a 20 ° C. atmosphere in the same manner as in Example 1, followed by pulse discharge for 2 seconds at a constant power of 1500 mW. The cycle was repeated until the lower limit voltage of 1500 mW pulse discharge reached 1.05V. In consideration of uses other than digital still cameras, the battery was continuously discharged at a constant current of 100 mA (low load) at 20 ° C., and the discharge capacity until the battery voltage reached 0.9 V was measured. Table 6 shows the obtained results (regarding 100 mA discharge, the discharge capacity of the battery Z5 is normalized to 100).

  When the ratio of nickel oxyhydroxide in the positive electrode mixture is greater than 80% by weight (battery Z9, battery Z10), better pulse characteristics than battery 2 (comparative battery that does not contain LiOH or the like in the electrolyte). Although given, the discharge capacity of 100 mA (low load) is significantly lower than that of the batteries Z1 to Z8. On the other hand, when the ratio of nickel oxyhydroxide is less than 10% by weight (battery Z1), it is better than battery 2, but it is understood that the pulse discharge cycle characteristics are greatly reduced as compared with batteries Z2 to Z10. From this result, also in the present invention battery using the zinc alloy containing aluminum and the KOH aqueous solution to which LiOH and aluminum hydroxide are added, the ratio of nickel oxyhydroxide in the positive electrode mixture is set to 10 to 80% by weight. Is presumed to be most preferable.

(Example 6)
Here, the amount of LiOH and the amount of aluminum hydroxide added to the electrolytic solution were examined. Electrolytic manganese dioxide, nickel oxyhydroxide prepared in Example 1 and graphite were mixed at a weight ratio of 50: 45: 5, and 1 part by weight of the electrolyte was mixed with 100 parts by weight of the mixed powder. The mixture was uniformly stirred and mixed to obtain a fixed particle size. The obtained granular material is press-molded into a hollow cylindrical shape to form a positive electrode mixture, a separator is inserted, an electrolyte solution is injected, and a gelled negative electrode (Zn containing 35 ppm of Al is used as an active material) is filled. AA size alkaline dry battery (battery P1) was assembled. In the battery P1, the alkaline solution composed of 36% by weight KOH and 0.05% by weight LiOH is used for any of the electrolytic solution contained in the positive electrode mixture, the electrolytic solution injected into the separator, and the electrolytic solution contained in the gelled zinc negative electrode. An aqueous solution was used, and aluminum hydroxide corresponding to an amount of 0.01% by weight with respect to the total amount of the electrolyte contained in the battery was added to the gelled zinc negative electrode.

  Subsequently, a battery P2, a battery P3, and a battery P4 were produced in the same manner as described above except that the ratio of LiOH in the electrolytic solution was changed to 0.1 wt%, 2.0 wt%, and 2.5 wt%. . In the same manner, the LiOH ratio in the electrolyte and the amount of aluminum hydroxide added in the gel negative electrode are changed in combinations as shown in Table 7, and batteries Q1 to Q4, batteries R1 to R4, and batteries S1 are changed. -Battery S4 was produced.

  In the same manner as in Example 1, the 12 types of batteries thus produced (initial state) were discharged at 20 ° C. for 28 seconds with a constant power of 650 mW and then pulse-discharged for 2 seconds with a constant power of 1500 mW. The cycle was repeated until the lower limit voltage of 1500 mW pulse discharge reached 1.05V. In consideration of the storage characteristics (storability) of practical alkaline batteries, these 12 types of batteries are stored in a 45 ° C. atmosphere for one month, and the same pulse discharge cycle test is performed on the subsequent batteries. went. The results are summarized in Table 7.

  In the first battery, regardless of the amount of aluminum hydroxide added, the batteries (battery P2, battery P3, battery Q2, battery Q3, battery R2) in which the amount of LiOH in the electrolyte solution was in the range of 0.1 to 2% by weight. Battery R3, Battery S2, and Battery S3) provide high performance. When LiOH in the electrolyte is less than 0.1% by weight (battery P1, battery Q1, battery R1, battery S1), or when LiOH in the electrolyte is greater than 2% by weight (battery P4, battery Q4, battery Although R4 and battery S4) are better than battery 2 that does not contain LiOH in the electrolyte, it can be seen that the effect of improving the pulse discharge cycle characteristics cannot be sufficiently obtained. If the amount of LiOH is less than 0.1% by weight, the absolute amount is too small, and thus the degree of the effect is small. If the amount of LiOH exceeds 2% by weight, the electrical conductivity of the electrolytic solution is reduced. It is presumed that it happened. From this result, it is presumed that in the present invention, the amount of LiOH in the electrolytic solution is more preferably in the range of 0.1 to 2% by weight.

  Among these batteries, particularly, the battery characteristics after storage are maintained at a high level because batteries (batteries) in which aluminum hydroxide is added at a ratio of 0.01 to 2% by weight in the electrolytic solution. P2, battery P3, battery Q2, battery Q3, battery R2, battery R3). In the case where the amount of aluminum hydroxide added is larger than 2% by weight of the total amount of the electrolyte (battery S2, battery S3), the effect of suppressing storage deterioration is not obtained at all. Deterioration such as a decrease in the degree occurs, and the characteristic deterioration after storage is slightly increased.

  From the above results, in the battery of the present invention using the zinc alloy containing aluminum and the KOH aqueous solution to which LiOH and aluminum hydroxide were added, the amounts of LiOH and aluminum compounds (such as aluminum hydroxide) contained in the alkaline electrolyte Is most preferably in the range of 0.1 to 2% by weight and 0.01 to 2% by weight, respectively.

In the above examples, nickel oxyhydroxide (composition: Ni _0.95 Zn _0.03 Co _0.02 (OH) ₂ raw material nickel hydroxide) in which a small amount of zinc / cobalt was dissolved was used. It is not limited to this. Moreover, although aluminum hydroxide was used as the aluminum compound to be added to the electrolytic solution, the same effect can be obtained by using other aluminum compounds such as aluminum oxide.

  Since the alkaline dry battery according to the present invention has high pulse discharge characteristics, it can be used as a power source for digital equipment (such as a digital still camera) with high power consumption, which cannot be adequately handled by conventional dry batteries.

1 is a cross-sectional front view of an alkaline battery according to an embodiment of the present invention. The figure which showed the discharge curve at the time of the pulse discharge cycle of the battery 1 The figure which showed the discharge curve at the time of the pulse discharge cycle of the battery 2 The figure which showed the positive / negative polarization curve at the time of the pulse discharge cycle of the battery 1 The figure which showed the positive / negative polarization curve at the time of the pulse discharge cycle of the battery 2

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positive electrode case 2 Graphite coating film 3 Positive electrode mixture pellet 4 Separator 5 Insulation cap 6 Gel-like negative electrode 7 Resin sealing board 8 Bottom plate 9 Insulation washer 10 Negative electrode collector 11 Exterior label

Claims (6)

An alkaline battery comprising a positive electrode containing nickel oxyhydroxide and manganese dioxide, a gelled negative electrode using zinc as an active material, and an alkaline electrolyte, wherein the alkaline electrolyte is a KOH aqueous solution to which LiOH is added. The alkaline dry battery according to claim 1, wherein the ratio of nickel oxyhydroxide in the positive electrode mixture is 10 to 80 wt% with respect to the whole positive electrode mixture. The alkaline dry battery according to claim 1 or 2, wherein the amount of LiOH contained in the total amount of the alkaline electrolyte (including the electrolyte in the gelled negative electrode and the positive electrode mixture) is 0.1 to 2% by weight. A positive electrode containing nickel oxyhydroxide and manganese dioxide, a gelled negative electrode using at least a zinc alloy containing aluminum as an active material, an alkaline electrolyte, and the alkaline electrolyte is a KOH aqueous solution to which LiOH and an aluminum compound are added. An alkaline battery characterized by that. 5. The alkaline dry battery according to claim 4, wherein a ratio of nickel oxyhydroxide in the positive electrode mixture is 10 to 80 wt% with respect to the whole positive electrode mixture. The amount of LiOH and aluminum compound contained in the total amount of the alkaline electrolyte (including the electrolyte in the gelled negative electrode and the positive electrode mixture) is 0.1 to 2% by weight and 0.01 to 2% by weight, respectively. The alkaline dry battery according to claim 4 or 5.

Images