JP2013020866A - Alkaline dry battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress generation of gas and liquid leakage caused when an alkaline dry battery is mistakenly connected in reverse polarity and is over charged, thereby securing battery safety.SOLUTION: In an alkaline dry battery, a hollow cylindrical positive electrode mixture, a negative electrode mixture arranged in a hollow part of the positive electrode mixture, a separator arranged between a positive electrode and a negative electrode, and an alkaline electrolyte are received in a closed-end cylindrical positive electrode can body. The alkaline dry battery includes a high resistance portion at at least a part of an outer peripheral surface of the positive electrode mixture.

Description

  The present invention relates to an alkaline battery.

  In alkaline batteries, if the battery is accidentally reverse-connected or overcharged, hydrogen gas may be generated for structural reasons, and if hydrogen gas is generated, the internal pressure will rise and fall into a dangerous state. It is devised to ensure the safety of alkaline batteries even when gas is generated.

  Specifically, in an alkaline battery, zinc is used as the negative electrode active material, and a strong alkaline electrolyte is used as the electrolytic solution. The electrolytic solution is in contact with the negative electrode. When an alkaline battery is reversely connected or overcharged by mistake, a reaction opposite to the normal battery reaction proceeds, and a zinc electrodeposition reaction proceeds on the negative electrode side. After zinc electrodeposition, the negative electrode potential drops below the hydrogen overvoltage, so that the hydrogen generation potential is reached and hydrogen gas may be generated. Since the alkaline battery is sealed, when hydrogen gas is generated in the alkaline battery, the atmospheric pressure in the alkaline battery increases, and the danger of the alkaline battery becomes high. The alkaline battery is configured such that when the internal pressure of the alkaline battery increases, the safety valve is opened to lower the atmospheric pressure in the alkaline battery.

JP 59-98452 A

  When the alkaline dry battery having the above configuration is erroneously reversely connected or overcharged, the generated gas is released by the cleavage of the safety valve, and the increase in the atmospheric pressure in the alkaline dry battery is suppressed. However, since the gas generation reaction associated with the reverse connection is not suppressed, when the battery internal reaction associated with the reverse connection proceeds rapidly, there is a possibility that the electrolyte leaks as the gas is released.

  In addition, when the alkaline battery having the above structure is reversely connected or overcharged with a structure having a highly airtight structure such as an underwater housing used when photographing an underwater light or camera underwater, it is discharged from the alkaline battery. As a result, the internal pressure of the structure is increased by the generated gas, and the highly airtight structure itself may be damaged.

  The present invention has been made in view of such a point, and is to suppress gas generated by reverse connection or overcharge in an alkaline dry battery and to suppress leakage.

  The alkaline dry battery of the present invention comprises a bottomed cylindrical positive electrode can, a hollow cylindrical positive electrode, a negative electrode disposed in a hollow portion of the positive electrode, and a separator disposed between the positive electrode and the negative electrode. The alkaline dry battery containing an alkaline electrolyte has a high resistance portion on at least a part of the outer peripheral surface of the positive electrode.

  ADVANTAGE OF THE INVENTION According to this invention, even if an alkaline dry battery will be in a reverse connection state, generation | occurrence | production of hydrogen gas can be suppressed and it can suppress that an alkaline electrolyte leaks out.

Half sectional view showing the configuration of the AA alkaline battery in this embodiment

  Before describing the embodiments of the present invention, the background to the completion of the present invention will be described.

  As described above, when an alkaline battery is erroneously reverse-connected or overcharged, hydrogen gas may be generated. When hydrogen gas is generated, the internal pressure rises and falls into a dangerous state. Therefore, it is devised to ensure the safety of the alkaline battery even if hydrogen gas is generated. However, gas generation itself is not suppressed. In the following, before explaining the matters considered by the present inventors, first, the reason why the alkaline electrolyte leaks when the alkaline dry battery is reversely connected will be described.

  For example, consider a case in which a circuit is configured by connecting only one battery in the reverse direction in a circuit in which a plurality of alkaline batteries are connected in series. At this time, in the alkaline battery that is reversely connected, the voltage of another alkaline battery that is connected in reverse to the alkaline battery is forcibly applied. As a result, the reverse reaction proceeds in the reversely connected alkaline battery. In other words, the zinc electrodeposition reaction proceeds on the negative electrode side, and the negative electrode potential drops below the hydrogen overvoltage, thereby reaching the hydrogen generation potential and generating hydrogen gas. On the other hand, on the positive electrode side, the oxidation reaction of the positive electrode active material proceeds, the positive electrode potential rises above the oxygen generation overvoltage, reaches the oxygen generation potential, and oxygen gas is generated.

  The present inventors have confirmed that generation of hydrogen gas on the negative electrode side stops when oxygen gas dissolved in the electrolyte is supplied to the negative electrode in which hydrogen gas is generated in a reverse connection state. The inventors of the present application have also confirmed that oxygen gas generation on the positive electrode side occurs as bubbles on the inner wall surface of the positive electrode can body 1 in the reverse connection state.

  Based on the above facts, the present inventors have found that oxygen gas generated as bubbles on the inner wall surface of the positive electrode can body 1 hardly reaches the negative electrode side during reverse connection discharge of an alkaline dry battery, and hydrogen gas on the negative electrode side. It was thought that the alkaline electrolyte easily leaks by adding not only the generation of oxygen gas on the positive electrode side, but also the generation of oxygen gas on the positive electrode side.

  As a result of detailed studies, the present inventors have found that the generation of hydrogen gas during reverse connection can be suppressed by devising the configuration of the positive electrode. Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a half cross-sectional view showing the configuration of an AA alkaline battery in this embodiment.

  As shown in FIG. 1, the AA alkaline battery includes a cylindrical positive electrode can 1 that is sealed at one end (the lower end in FIG. 1). It is covered. The positive electrode can 1 serves as both a positive electrode terminal and a positive electrode current collector, and a hollow cylindrical positive electrode 2 is inscribed in the positive electrode can 1. A separator 4 is provided in the hollow portion of the positive electrode 2, the separator 4 is formed in a cylindrical shape with one end sealed, and a negative electrode 3 is provided in the hollow portion of the separator 4. As described above, in the positive electrode can 1, the positive electrode 2, the separator 4, and the negative electrode 3 are arranged in this order from the periphery toward the center.

The opening (upper end in FIG. 1) of the positive electrode can body 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 resinous sealing body 5. The negative electrode terminal plate 7 is electrically connected to the negative electrode current collector 6. The sealing body 5 is physically fixed to the negative electrode current collector 6 and the negative electrode terminal plate 7. When manufacturing an AA alkaline battery, power generation elements such as the positive electrode 2 and the negative electrode 3 are first accommodated in the positive electrode can body 1, and then the opening of the positive electrode can body 1 is sealed using the assembly sealing body 9.

  The positive electrode 2, the negative electrode 3 and the separator 4 contain an alkaline electrolyte (not shown). 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.

  The components of the AA alkaline battery in this embodiment will be described in order.

  The positive electrode can body 1 is press-molded into a predetermined size and shape using, for example, a known method described in JP-A-60-180058 or JP-A-11-144690 using a steel plate plated with nickel. Is obtained.

  The positive electrode 2 includes, for example, a mixture of a positive electrode active material such as electrolytic manganese dioxide powder, a conductive agent such as graphite powder, and an alkaline electrolyte. Further, a binder such as polyethylene powder or a lubricant such as stearate may be added to the positive electrode 2 as appropriate. The details of the positive electrode 2 will be described later.

  As the negative electrode 3, for example, a gelling agent such as polyacrylic acid is added to an alkaline electrolyte and processed into a gel, and zinc (negative electrode active material) is dispersed in the gel. . Further, in order to suppress the generation of zinc dendrite, a small amount of silicon compound such as silicic acid or a salt thereof may be appropriately added to the negative electrode 3.

  As the separator 4, for example, a nonwoven fabric mainly composed of polyvinyl alcohol fiber and rayon fiber is used. The separator 4 is obtained by a known method described in, for example, Japanese Patent Laid-Open No. 6-163024 or Japanese Patent Laid-Open No. 2006-32320.

  A through hole (not shown) for press-fitting the negative electrode current collector 6 is provided at the center of the sealing body 5, and a hollow cylindrical thin wall portion (not shown) that functions as a safety valve is provided around the through hole. An outer peripheral edge (not shown) is continuously formed on the outer periphery of the hollow cylindrical thin-walled portion. The sealing body 5 is obtained by, for example, injection molding nylon or polypropylene into a predetermined size and shape.

  The negative electrode current collector 6 is manufactured by pressing a metal wire such as brass into a nail mold having a predetermined size.

  The negative electrode terminal plate 7 is provided with a terminal portion (not shown) that seals the opening of the positive electrode can 1 and a peripheral flange that extends from the terminal portion (not shown) and contacts the sealing member 5. A plurality of gas holes (not shown) for releasing pressure when the safety valve of the sealing body 5 is operated are provided in the peripheral flange portion. The negative electrode terminal plate 7 is obtained, for example, by pressing a steel plate plated with nickel or a steel plate plated with tin into a predetermined size and shape.

The positive electrode in this embodiment has a high resistance portion at least in part. Here, when the alkaline battery is reversely connected, not only the negative electrode potential reaches the hydrogen generation potential and hydrogen gas is generated from the negative electrode side, but also the positive electrode potential rises and reaches the oxygen generation potential. Oxygen gas is generated from the side. Usually, a large amount of oxygen gas on the positive electrode side is generated from the inner wall side of the positive electrode can body 1 having low reaction resistance. In the above configuration, by providing a portion with a small amount of the conductive agent contained in the positive electrode, that is, a high resistance portion, it is possible to disperse the oxygen gas generation portion at the positive electrode. Specifically, oxygen gas can be generated from the inside of the positive electrode. Here, since the specific surface area inside the positive electrode is larger than the interface between the inner wall of the positive electrode can, which is an oxygen gas generation site, and the positive electrode, the generated oxygen gas can be dissolved in the electrolytic solution and reach the negative electrode side. As a result, it is possible to suppress the hydrogen gas generation reaction from the negative electrode side, to suppress an increase in internal pressure at the time of reverse connection, and to suppress leakage of the alkaline electrolyte at the time of reverse connection.

  The positive electrode in the present embodiment is composed of a plurality of hollow cylindrical positive electrode pellets loaded in a stack in the positive electrode can body 1 as in the conventional positive electrode in an AA alkaline battery, and the positive electrode pellet includes electrolytic manganese dioxide. In addition to the positive electrode active material such as powder, carbon material (carbon) such as graphite powder is included as a conductive agent.

  When the high resistance portion is 50% or less of the entire positive electrode, the distribution of the resistance component in the entire positive electrode including the positive electrode can 1 and the positive electrode pellet is homogenized. Oxygen generation at the corresponding high resistance portion can be reliably reduced, and this is preferable in that an effect of dispersing the generation site of oxygen gas generated during reverse connection over the entire positive electrode can be obtained.

  In addition, when the content of the conductive agent on the outer peripheral surface of the positive electrode pellet corresponding to the positive electrode can body 1 side is less than that of the positive electrode pellets at other positions, and the high resistance portion is disposed at a site on the side in contact with the positive electrode can body, Oxygen generation location was generated because it was dispersed throughout the positive electrode without concentrating on the contact area between the positive electrode can body and the outer peripheral surface of the positive electrode pellet, thereby preventing oxygen from being bubbled and easily dissolved in the electrolyte. Oxygen is preferable in that it is efficiently absorbed on the negative electrode side.

  Furthermore, in a plurality (three or more) of positive electrode pellets loaded on the stack in the positive electrode can 1, the conductive agent content of the positive electrode pellets located at both ends of the stack is less than the positive electrode pellets at other positions, When the resistance part is provided on at least one of the opening side and the bottom side of the positive electrode can body, the oxygen generation sites that have been concentrated due to the presence of a large amount of electrolyte solution are dispersed throughout the positive electrode, thereby causing bubbles. This is preferable in that the generated oxygen is efficiently absorbed on the negative electrode side because it is prevented and easily converted into dissolved oxygen.

  The number of pellets constituting the positive electrode mixture is not limited as long as the graphite content distribution condition is satisfied, and an effect is obtained.

  In the case of the resistance of the mixture constituting the positive electrode, a flat plate using powder collected from the side of the positive electrode pellet in contact with the positive electrode can body (outside of the hollow pellet) and the opposite side of the negative electrode (inside of the hollow pellet) A pellet is prepared, and the level of resistance can be measured by DC resistance measurement by a four-probe method described in JISK7194.

  Examples of the present invention are shown below. In this example, an AA alkaline battery was manufactured according to the method described below, and then the manufactured AA alkaline battery was reversely connected to check for leakage.

Example 1
First, particles of a zinc alloy containing 0.003% by weight of Al, 0.015% by weight of Bi and 0.020% by weight of In based on the weight of zinc were prepared by a gas atomization method. Thereafter, the produced zinc alloy particles were classified using a sieve. By this classification, a negative electrode active material having a particle size range of 35 to 300 mesh and a ratio of zinc alloy particles having a particle size of 200 mesh (75 μm) or less was 30%.

Thereafter, polyacrylic acid and sodium polyacrylate are added so that the total weight becomes 2.2 parts by weight with respect to 100 parts by weight of 34.5% by weight potassium hydroxide aqueous solution (containing 2% by weight of ZnO). In addition, they were mixed and gelled. As a result, a gel electrolyte was obtained. Thereafter, the obtained gel electrolyte was allowed to stand for 24 hours and sufficiently aged.

  Then, to the gel electrolyte solution obtained above, the zinc alloy particles having a weight ratio of 2.00 times the predetermined amount of the gel electrolyte solution and 100 parts by weight of the zinc alloy particles Then, 0.05 part by weight of a phosphoric acid surfactant (sodium alcohol phosphate ester having an average molecular weight of about 210) was thoroughly mixed. As a result, a gelled negative electrode was obtained.

  Next, electrolytic manganese dioxide (HTHTF (product number) manufactured by Tosoh Corporation) and graphite (SP-20 (product number) manufactured by Nippon Graphite Industry Co., Ltd.) are blended at a weight ratio of 94: 6 to obtain a mixed powder. It was. Then, after mixing 1.5 parts by weight of electrolytic solution (39% by weight potassium hydroxide aqueous solution (including 2% by weight of ZnO)) and 0.2 part by weight of polyethylene binder with respect to 100 parts by weight of the mixed powder, a mixer To prepare a granulated product that was uniformly stirred and mixed to adjust the particle size. On the other hand, after mixing 1.5 parts by weight of electrolytic solution (39% by weight potassium hydroxide aqueous solution (containing 2% by weight of ZnO)) and 0.2 part by weight of polyethylene binder with 100 parts by weight of electrolytic manganese dioxide powder Then, the mixture was uniformly stirred and mixed with a mixer to prepare a granulated product having a fixed particle size. Of the obtained two types of granular materials, the granular material blended with graphite was placed inside the hollow cylindrical shape, and the granular material not blended with graphite was placed on the outside by the same weight, and pressure-molded. In this way, a positive electrode pellet having a higher resistance on the outer peripheral surface than that on the inner peripheral surface was obtained.

  Subsequently, an AA alkaline battery for evaluation was produced. Specifically, as shown in FIG. 1, four positive electrode pellets (the weight of one is 2.95 g) obtained above are inserted into the positive electrode can body 1, and the positive electrode can body 1 is reused. The positive electrode can 1 was brought into close contact with the inner surface by pressurization. In addition, it was set as the pellet A, the pellet B, the pellet C, and the pellet D from the sealing board side, respectively. And after inserting the separator 4 and the base paper for insulating the bottom part of the positive electrode can 1 inside this positive electrode pellet, electrolyte solution (34.5 weight% potassium hydroxide aqueous solution (it contains 2 weight% of ZnO) )) Was injected. After the injection, 6.2 g of gelled negative electrode 3 (the weight of zinc alloy particles was 4.1 g) was filled inside the separator 4. Then, the opening of the positive electrode can 1 was sealed using the assembly sealing body 9 in which the 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 caulked to the edge of the opening of the positive electrode can body 1 through the end of the sealing body 5. The positive electrode can 1 was brought into close contact with the opening. Then, the outer surface of the positive electrode can 1 was covered with an outer label 8 to produce an AA alkaline battery according to the example. It was set to 1.

  Here, as the sealing body 5, 6, 6 nylon was produced as a material. The negative electrode current collector 6 is a nail shape having a thickness (φ) of 1.425 mm and a length of 33 mm. The brass wire has a Cu content of 65% with respect to the weight of the negative electrode current collector 6. Was used. In order to coat the brass wire impurities, the surface of the negative electrode current collector was tin electroplated to a thickness of 1.0 μm. As the separator 4, a separator for alkaline dry batteries (a composite fiber made of vinylon and Tencel (registered trademark)) manufactured by Kuraray Co., Ltd. was used.

(Example 2)
Electrolytic manganese dioxide and graphite were blended in a weight ratio of 94: 6 to obtain a mixed powder. Then, after mixing 1.5 parts by weight of electrolytic solution (39% by weight potassium hydroxide aqueous solution (including 2% by weight of ZnO)) and 0.2 part by weight of polyethylene binder with respect to 100 parts by weight of the mixed powder, a mixer To prepare a granulated product that was uniformly stirred and mixed to adjust the particle size. On the other hand, electrolytic manganese dioxide powder and graphite were blended at a weight ratio of 97: 3 to obtain a mixed powder. And after mixing 1.5 weight part of electrolyte solution (39 weight% potassium hydroxide aqueous solution (2 weight% of ZnO is included)) and 0.2 weight part of polyethylene binder with respect to 100 weight part of this mixed powder, it is a mixer. A granular material that was uniformly stirred and mixed to obtain a fixed particle size was prepared. Of the obtained two types of granular materials, a granular material with a compounding ratio of 94: 6 with graphite was placed inside the hollow cylindrical shape.
: The granular material which is 3 is arrange | positioned for the same weight on the outer side, and was pressure-molded. In this way, a positive electrode pellet having a higher resistance on the outer peripheral surface than that on the inner peripheral surface was obtained. In all other cases, the battery No. In the same manner as in Battery No. 1, 2 was produced.

(Example 3)
Electrolytic manganese dioxide and graphite were blended in a weight ratio of 94: 6 to obtain a mixed powder. And after mixing 1.5 weight part of electrolyte solution (39 weight% potassium hydroxide aqueous solution (2% of ZnO is included)) and 0.2 weight part of polyethylene binder with respect to 100 weight part of this mixed powder, a mixer is mixed. To prepare a granulated product that was uniformly stirred and mixed to adjust the particle size. On the other hand, after mixing 1.5 parts by weight of electrolytic solution (39% by weight potassium hydroxide aqueous solution (containing 2% by weight of ZnO)) and 0.2 part by weight of polyethylene binder with 100 parts by weight of electrolytic manganese dioxide powder Then, the mixture was uniformly stirred and mixed with a mixer to prepare a granulated product having a fixed particle size. The obtained two kinds of granular materials were each pressed into a hollow cylindrical shape to obtain a positive electrode pellet.

  Subsequently, as shown in FIG. 1, among the positive electrode pellets (the weight of one piece is 2.95 g) obtained as described above, two pieces corresponding to both ends of the positive electrode can body are graphite. The positive electrode can can be obtained by inserting a total of four positive electrode mixture pellets having a mixing ratio of 94: 6 with graphite and re-pressurizing within the positive electrode can body 1. It was made to adhere to the inner surface of the body 1. In all other cases, the battery No. In the same manner as in No. 1, the battery no. 3 was produced.

Example 4
Electrolytic manganese dioxide and graphite were blended in a weight ratio of 94: 6 to obtain a mixed powder. And after mixing 1.5 weight part of electrolyte solution (39 weight% potassium hydroxide aqueous solution (2% of ZnO is included)) and 0.2 weight part of polyethylene binder with respect to 100 weight part of this mixed powder, a mixer is mixed. To prepare a granulated product that was uniformly stirred and mixed to adjust the particle size. On the other hand, electrolytic manganese dioxide powder and graphite were blended at a weight ratio of 97: 3 to obtain a mixed powder. And after mixing 1.5 weight part of electrolyte solution (39 weight% potassium hydroxide aqueous solution (2 weight% of ZnO is included)) and 0.2 weight part of polyethylene binder with respect to 100 weight part of this mixed powder, it is a mixer. A granular material that was uniformly stirred and mixed to obtain a fixed particle size was prepared. The obtained two kinds of granular materials were each pressed into a hollow cylindrical shape to obtain a positive electrode pellet.

  Subsequently, as shown in FIG. 1, in the positive electrode can body 1, two positive electrode mixture pellets (weight of 2.95 g each) corresponding to both ends of the positive electrode can body are obtained. Inserts a total of 4 positive electrode mixture pellets with a compounding ratio of 97: 3 with graphite, and two pellets with a compounding ratio of 94: 6 with graphite, corresponding to the central portion, to form a positive electrode can 1 The inner surface of the positive electrode can 1 was brought into close contact with the inside by re-pressurization. In all other cases, the battery No. In the same manner as in No. 1, the battery no. 4 was produced.

(Example 5)
Electrolytic manganese dioxide and graphite were blended in a weight ratio of 94: 6 to obtain a mixed powder. And after mixing 1.5 weight part of electrolyte solution (39 weight% potassium hydroxide aqueous solution (2% of ZnO is included)) and 0.2 weight part of polyethylene binder with respect to 100 weight part of this mixed powder, a mixer is mixed. To prepare a granulated product that was uniformly stirred and mixed to adjust the particle size. On the other hand, electrolytic manganese dioxide powder and graphite were blended at a weight ratio of 97: 3 to obtain a mixed powder. And after mixing 1.5 weight part of electrolyte solution (39 weight% potassium hydroxide aqueous solution (2 weight% of ZnO is included)) and 0.2 weight part of polyethylene binder with respect to 100 weight part of this mixed powder, it is a mixer. A granular material that was uniformly stirred and mixed to obtain a fixed particle size was prepared. Of the obtained two types of granular materials, the granular material having a blending ratio of 94: 6 with graphite is placed inside the hollow cylindrical shape, and the granular material being 97: 3 is placed on the outside by the same weight and subjected to pressure molding. Thus, a positive electrode pellet having a higher resistance on the outer peripheral surface than that on the inner peripheral surface was obtained. Moreover, only the granular material which is the compounding ratio 97: 3 with graphite among the two types of obtained granular materials was pressure-molded into a hollow cylindrical shape, and the positive electrode mixture pellet was obtained.

  Subsequently, as shown in FIG. 1, among the positive electrode pellets obtained above (with one piece having a weight of 2.95 g), two pieces corresponding to the central portion are blended with graphite. The cathode pellets in which the granular material having a ratio of 94: 6 is arranged on the inner peripheral side of the hollow cylindrical type and the granular material having a ratio of 97: 3 are arranged on the outer peripheral side, and two corresponding to both ends of the positive electrode can body are blended with graphite. A total of four pellets having a ratio of 97: 3 were inserted and re-pressurized in the positive electrode can body 1 to be brought into close contact with the inner surface of the positive electrode can body 1. In all other cases, the battery No. In the same manner as in No. 1, the battery no. 5 was produced.

(Example 6)
Electrolytic manganese dioxide and graphite were blended at a weight ratio of 90:10 to obtain a mixed powder. And after mixing 1.5 weight part of electrolyte solution (39 weight% potassium hydroxide aqueous solution (2% of ZnO is included)) and 0.2 weight part of polyethylene binder with respect to 100 weight part of this mixed powder, a mixer is mixed. To prepare a granulated product that was uniformly stirred and mixed to adjust the particle size. On the other hand, after mixing 1.5 parts by weight of electrolytic solution (39% by weight potassium hydroxide aqueous solution (containing 2% by weight of ZnO)) and 0.2 part by weight of polyethylene binder with 100 parts by weight of electrolytic manganese dioxide powder Then, the mixture was uniformly stirred and mixed with a mixer to prepare a granulated product having a fixed particle size. The obtained two kinds of granular materials were each pressed into a hollow cylindrical shape to obtain a positive electrode pellet.

  Subsequently, as shown in FIG. 1, among the positive electrode pellets (the weight of one piece is 2.95 g) obtained as described above, two pieces corresponding to both ends of the positive electrode can body are graphite. The positive electrode can is obtained by inserting a total of four positive electrode mixture pellets having a mixing ratio of 90:10 with graphite and repressurizing within the positive electrode can body 1. It was made to adhere to the inner surface of the body 1. In all other cases, the battery No. In the same manner as in No. 1, the battery no. 6 was produced.

(Example 7)
Electrolytic manganese dioxide and graphite were blended at a weight ratio of 90:10 to obtain a mixed powder. And after mixing 1.5 weight part of electrolyte solution (39 weight% potassium hydroxide aqueous solution (2% of ZnO is included)) and 0.2 weight part of polyethylene binder with respect to 100 weight part of this mixed powder, a mixer is mixed. To prepare a granulated product that was uniformly stirred and mixed to adjust the particle size. On the other hand, electrolytic manganese dioxide powder and graphite were blended at a weight ratio of 95: 5 to obtain a mixed powder. And after mixing 1.5 weight part of electrolyte solution (39 weight% potassium hydroxide aqueous solution (2 weight% of ZnO is included)) and 0.2 weight part of polyethylene binder with respect to 100 weight part of this mixed powder, it is a mixer. A granular material that was uniformly stirred and mixed to obtain a fixed particle size was prepared. The obtained two kinds of granular materials were each pressed into a hollow cylindrical shape to obtain a positive electrode pellet.

  Subsequently, as shown in FIG. 1, in the positive electrode can body 1, two positive electrode mixture pellets (weight of 2.95 g each) corresponding to both ends of the positive electrode can body are obtained. Inserts a total of 4 positive electrode mixture pellets with a compounding ratio of 95: 5 with graphite, and two pellets with a compounding ratio with graphite of 90:10 corresponding to the central portion, and the positive electrode can 1 The inner surface of the positive electrode can 1 was brought into close contact with the inside by re-pressurization. In all other cases, the battery No. In the same manner as in No. 1, the battery no. 7 was produced.

(Example 8)
Electrolytic manganese dioxide and graphite were blended at a weight ratio of 90:10 to obtain a mixed powder. And after mixing 1.5 weight part of electrolyte solution (39 weight% potassium hydroxide aqueous solution (2% of ZnO is included)) and 0.2 weight part of polyethylene binder with respect to 100 weight part of this mixed powder, a mixer is mixed. To prepare a granulated product that was uniformly stirred and mixed to adjust the particle size. On the other hand, electrolytic manganese dioxide powder and graphite were blended at a weight ratio of 95: 5 to obtain a mixed powder. Then, 100 parts by weight of the mixed powder was used as an electrolytic solution (39% by weight potassium hydroxide aqueous solution (ZnO
2) by weight) and 1.5 parts by weight of polyethylene binder and 0.2 part by weight of polyethylene binder were mixed, and the mixture was uniformly stirred and mixed with a mixer to prepare a granulated product having a fixed particle size. Of the two types of granule obtained, the granule having a blending ratio of 90:10 with graphite is placed inside the hollow cylindrical shape, and the granule not blended with graphite is placed on the outside by the same weight, and pressure-molded. Thus, a positive electrode pellet having a higher resistance on the outer peripheral surface than that on the inner peripheral surface was obtained. Of the two types of granules obtained, only the granules having a blending ratio of 95: 5 with graphite were pressure-molded into a hollow cylindrical mold to obtain positive electrode mixture pellets.

  Subsequently, as shown in FIG. 1, among the positive electrode pellets obtained above (with one piece having a weight of 2.95 g), two pieces corresponding to the central portion are blended with graphite. The positive pellets in which the granular material having a ratio of 90:10 is arranged on the inner peripheral side of the hollow cylindrical type and the granular material not containing graphite is arranged on the outer peripheral side, two pieces corresponding to both ends of the positive electrode can body are made of graphite. A total of four pellets having a blending ratio of 95: 5 were inserted and re-pressurized in the positive electrode can body 1 to be brought into close contact with the inner surface of the positive electrode can body 1. In all other cases, the battery No. In the same manner as in No. 1, the battery no. 8 was produced.

Example 9
Electrolytic manganese dioxide and graphite were blended at a weight ratio of 90:10 to obtain a mixed powder. And after mixing 1.5 weight part of electrolyte solution (39 weight% potassium hydroxide aqueous solution (2% of ZnO is included)) and 0.2 weight part of polyethylene binder with respect to 100 weight part of this mixed powder, a mixer is mixed. To prepare a granulated product that was uniformly stirred and mixed to adjust the particle size. On the other hand, after mixing 1.5 parts by weight of electrolytic solution (39% by weight potassium hydroxide aqueous solution (containing 2% by weight of ZnO)) and 0.2 part by weight of polyethylene binder with 100 parts by weight of electrolytic manganese dioxide powder Then, the mixture was uniformly stirred and mixed with a mixer to prepare a granulated product having a fixed particle size. The outer periphery of the inner peripheral surface compared to the inner peripheral surface is formed by placing the granular material with a compounding ratio of 90:10 with graphite on the inner side of the hollow cylindrical shape and molding the non-graphite granular material on the outer side by the same weight. A positive electrode pellet having high surface resistance was obtained. In all other cases, the battery No. In the same manner as in No. 1, the battery no. 9 was produced.

(Example 10)
Electrolytic manganese dioxide and graphite were blended at a weight ratio of 90:10 to obtain a mixed powder. And after mixing 1.5 weight part of electrolyte solution (39 weight% potassium hydroxide aqueous solution (2% of ZnO is included)) and 0.2 weight part of polyethylene binder with respect to 100 weight part of this mixed powder, a mixer is mixed. To prepare a granulated product that was uniformly stirred and mixed to adjust the particle size. On the other hand, electrolytic manganese dioxide powder and graphite were blended at a weight ratio of 95: 5 to obtain a mixed powder. And after mixing 1.5 weight part of electrolyte solution (39 weight% potassium hydroxide aqueous solution (2 weight% of ZnO is included)) and 0.2 weight part of polyethylene binder with respect to 100 weight part of this mixed powder, it is a mixer. A granular material that was uniformly stirred and mixed to obtain a fixed particle size was prepared. Of the two types of granule obtained, the granule with a blending ratio of 90:10 with graphite is placed inside the hollow cylindrical mold and the granule with 95: 5 is placed on the outside by the same weight, and pressure molding did. In this way, a positive electrode pellet having a higher resistance on the outer peripheral surface than that on the inner peripheral surface was obtained. In all other cases, the battery No. In the same manner as in No. 1, the battery no. 10 was produced.

(Comparative Example 1)
Electrolytic manganese dioxide and graphite were blended in a weight ratio of 94: 6 to obtain a mixed powder. And after mixing 1.5 weight part of electrolyte solution (39 weight% potassium hydroxide aqueous solution (2% of ZnO is included)) and 0.2 weight part of polyethylene binder with respect to 100 weight part of this mixed powder, a mixer is mixed. The mixture was stirred and mixed uniformly to adjust the particle size to a constant particle size, and the resulting granule was pressurized to form a hollow cylinder. In this way, a positive electrode pellet was obtained. In all other cases, the battery No. In the same manner as in No. 1, the battery no. 11 was produced.

(Comparative Example 2)
Electrolytic manganese dioxide and graphite were blended in a weight ratio of 94: 6 to obtain a mixed powder. And after mixing 1.5 weight part of electrolyte solution (39 weight% potassium hydroxide aqueous solution (2% of ZnO is included)) and 0.2 weight part of polyethylene binder with respect to 100 weight part of this mixed powder, a mixer is mixed. To prepare a granulated product that was uniformly stirred and mixed to adjust the particle size. On the other hand, after mixing 1.5 parts by weight of electrolytic solution (39% by weight potassium hydroxide aqueous solution (containing 2% by weight of ZnO)) and 0.2 part by weight of polyethylene binder with 100 parts by weight of electrolytic manganese dioxide powder Then, the mixture was uniformly stirred and mixed with a mixer to prepare a granulated product having a fixed particle size. Of the obtained two types of granular materials, the granular material blended with graphite was placed on the outer side of the hollow cylindrical shape, and the granular material not blended with graphite was placed on the inner side by the same weight, followed by pressure molding. In this way, a positive electrode pellet having a higher resistance on the inner peripheral surface than that on the outer peripheral surface was obtained. In all other cases, the battery No. In the same manner as in No. 1, the battery no. 12 was produced.

(Comparative Example 3)
Electrolytic manganese dioxide and graphite were blended in a weight ratio of 94: 6 to obtain a mixed powder. And after mixing 1.5 weight part of electrolyte solution (39 weight% potassium hydroxide aqueous solution (2% of ZnO is included)) and 0.2 weight part of polyethylene binder with respect to 100 weight part of this mixed powder, a mixer is mixed. To prepare a granulated product that was uniformly stirred and mixed to adjust the particle size. On the other hand, electrolytic manganese dioxide powder and graphite were blended at a weight ratio of 97: 3 to obtain a mixed powder. And after mixing 1.5 weight part of electrolyte solution (39 weight% potassium hydroxide aqueous solution (2 weight% of ZnO is included)) and 0.2 weight part of polyethylene binder with respect to 100 weight part of this mixed powder, it is a mixer. A granular material that was uniformly stirred and mixed to obtain a fixed particle size was prepared. Of the obtained two types of granular materials, the granular material with a blending ratio of 94: 6 with graphite is placed on the outside of the hollow cylindrical shape, and the granular material of 97: 3 is placed on the inside with the same weight, and pressure molding did. In this way, a positive electrode pellet having a higher resistance on the inner peripheral surface than that on the outer peripheral surface was obtained. In all other cases, the battery No. In the same manner as in No. 1, the battery no. 13 was produced.

(Comparative Example 4)
Electrolytic manganese dioxide and graphite were blended in a weight ratio of 94: 6 to obtain a mixed powder. And after mixing 1.5 weight part of electrolyte solution (39 weight% potassium hydroxide aqueous solution (2% of ZnO is included)) and 0.2 weight part of polyethylene binder with respect to 100 weight part of this mixed powder, a mixer is mixed. To prepare a granulated product that was uniformly stirred and mixed to adjust the particle size. On the other hand, after mixing 1.5 parts by weight of electrolytic solution (39% by weight potassium hydroxide aqueous solution (containing 2% by weight of ZnO)) and 0.2 part by weight of polyethylene binder with 100 parts by weight of electrolytic manganese dioxide powder Then, the mixture was uniformly stirred and mixed with a mixer to prepare a granulated product having a fixed particle size. The obtained two kinds of granular materials were each pressed into a hollow cylindrical shape to obtain a positive electrode pellet.

  Subsequently, as shown in FIG. 1, in the positive electrode can body 1, two of the positive electrode pellets obtained above (weight of 2.95 g) correspond to both end portions of the positive electrode can body. The positive electrode mixture pellets with a mixing ratio of 94: 6 with graphite were inserted into a total of four pellets not containing graphite, corresponding to the central portion, and repressurized in the positive electrode can 1 to recharge the positive electrode. It was made to adhere to the inner surface of the can 1. In all other cases, the battery No. In the same manner as in No. 1, the battery no. 14 was produced.

(Comparative Example 5)
Electrolytic manganese dioxide and graphite were blended in a weight ratio of 94: 6 to obtain a mixed powder. And after mixing 1.5 weight part of electrolyte solution (39 weight% potassium hydroxide aqueous solution (2% of ZnO is included)) and 0.2 weight part of polyethylene binder with respect to 100 weight part of this mixed powder, a mixer is mixed. To prepare a granulated product that was uniformly stirred and mixed to adjust the particle size. On the other hand, electrolytic manganese dioxide powder and graphite were blended at a weight ratio of 97: 3 to obtain a mixed powder. And after mixing 1.5 weight part of electrolyte solution (39 weight% potassium hydroxide aqueous solution (2 weight% of ZnO is included)) and 0.2 weight part of polyethylene binder with respect to 100 weight part of this mixed powder, it is a mixer. A granular material that was uniformly stirred and mixed to obtain a fixed particle size was prepared. The obtained two kinds of granular materials were each pressed into a hollow cylindrical shape to obtain a positive electrode pellet.

  Subsequently, as shown in FIG. 1, among the positive electrode pellets (the weight of one piece is 2.95 g) obtained as described above, two pieces corresponding to both ends of the positive electrode can body are graphite. Insert a total of 4 pellets with a mixing ratio of 94: 6 and 2 positive pellets with a mixing ratio of 97: 3 with graphite in the center portion, and re-add in the positive electrode can 1 The positive electrode can 1 was brought into close contact with the inner surface by pressing. In all other cases, the battery No. In the same manner as in No. 1, the battery no. 15 was produced.

(Comparative Example 5)
Electrolytic manganese dioxide and graphite were blended at a weight ratio of 90:10 to obtain a mixed powder. And after mixing 1.5 weight part of electrolyte solution (39 weight% potassium hydroxide aqueous solution (2% of ZnO is included)) and 0.2 weight part of polyethylene binder with respect to 100 weight part of this mixed powder, a mixer is mixed. To prepare a granulated product that was uniformly stirred and mixed to adjust the particle size. On the other hand, after mixing 1.5 parts by weight of electrolytic solution (39% by weight potassium hydroxide aqueous solution (containing 2% by weight of ZnO)) and 0.2 part by weight of polyethylene binder with 100 parts by weight of electrolytic manganese dioxide powder Then, the mixture was uniformly stirred and mixed with a mixer to prepare a granulated product having a fixed particle size. The obtained two kinds of granular materials were each pressed into a hollow cylindrical shape to obtain a positive electrode pellet.

  Subsequently, as shown in FIG. 1, in the positive electrode can body 1, two of the positive electrode pellets obtained above (weight of 2.95 g) correspond to both end portions of the positive electrode can body. The positive electrode mixture pellets having a blending ratio of 90:10 with graphite were inserted in a total of four pellets not containing graphite, corresponding to the central portion, and repressurized in the positive electrode can 1 to recharge the positive electrode. It was made to adhere to the inner surface of the can 1. In all other cases, the battery No. In the same manner as in No. 1, the battery no. 16 was produced.

(Battery evaluation)
The battery of the example (new battery) was constituted by a circuit in which four batteries were connected in series via an external resistance of 16Ω and discharged. Battery No. The discharge rate was determined by setting the capacity at 6 to “100%”.

  Next, the battery No. 1 to battery no. 10 (new battery) was forcibly charged, and a gas generation leakage test assuming reverse connection was performed. The evaluation method consists of a circuit in which three batteries are connected in series to an external resistor of 16Ω, and one test battery is further connected in the reverse direction in the circuit, and the test battery is charged up to 1 After discharging for a period of time, the presence or absence of leakage of the alkaline battery was examined. Battery No. of Comparative Example A similar test was performed on 11 to 16 to check for the presence of leakage. Here, three batteries are connected in series via a resistor and one is connected in the opposite direction to make one set, and 10 sets each (total number of AA alkaline batteries is 40) are tested. The rate of occurrence of leakage (%) was determined. Table 1 shows the test results of these batteries.

  Battery No. According to No. 11, when the graphite mixture ratio of the positive electrode mixture is uniform, the leakage rate due to reverse connection is as high as 80%.

  Battery No. 1 to battery no. 2 and battery no. 9 to Battery No. According to No. 10, by reducing the graphite blending ratio in the outer peripheral portion of the cylindrical positive electrode mixture, the discharge rate is slightly reduced, but there is an effect of suppressing leakage due to reverse connection.

  Battery No. 3-Battery No. 4 and battery no. 6 to Battery No. 7 shows that among the pellets in which the graphite compounding ratio of the cylindrical positive electrode is changed, the pellets with a reduced graphite compounding ratio are arranged at both ends of the positive electrode can body 1 (pellet A, pellet D), and the discharge rate is slightly Although it decreases, there is an effect of suppressing leakage due to reverse connection.

  Battery No. 5 and battery no. 8 has both the characteristics of Example 2 and Example 4 in which the graphite compounding ratio of the outer peripheral portion of the cylindrical positive electrode is reduced and the pellets with the reduced graphite compounding ratio are arranged at both ends of the positive electrode can body 1. By doing so, the discharge rate is slightly reduced, but there is an effect of suppressing leakage due to reverse connection.

  Battery No. 12 to Battery No. According to No. 16, when a cylindrical positive electrode with a reduced graphite compounding ratio was placed in the center of the positive electrode can body 1 (pellet B, pellet C), the discharge rate decreased to 92% or less. Particularly in Comparative Examples 4 and 5 in which the graphite blending ratio in the inner part of the pellet was lowered, the discharge rate was greatly reduced and was lower than 90%. At the same time, there was almost no effect of suppressing leakage during reverse connection in Comparative Examples 2 to 5.

  As described above, the battery No. 1 to battery no. 10 and comparative battery No. 10. 11 to battery no. It was speculated that the reason for the difference in the occurrence rate of the liquid leakage from 16 was due to the mechanism described in the above embodiment.

Specifically, when an AA alkaline battery is reversely connected and overcharged, hydrogen gas is generated from the negative electrode inside the battery, and oxygen gas is generated from the positive electrode. A large amount of oxygen gas is generated from the inside of the positive electrode can, particularly from the inside of both ends of the positive electrode can body 1. This is the location with the lowest resistance in the positive electrode, and it can be predicted that bubbles are generated because the oxygen generation locations are concentrated.

  At this time, the battery No. 1 and battery no. 2, Battery No. 9, Battery No. 10, the graphite on the side of the positive electrode pellet in contact with the inside of the battery can body was reduced to increase the resistance. Therefore, the oxygen gas generation site at the time of overdischarge was not concentrated inside the battery can body, and oxygen was also generated inside the positive electrode mixture. Since gas generation occurred, it can be predicted that hydrogen gas generation suppression of the negative electrode as dissolved oxygen in the electrolyte solution was reached.

  Battery No. 3 and battery no. 4. Battery No. 6. Battery No. In No. 7, since the resistance was increased by reducing the graphite of the positive electrode pellets at both ends of the can body, which is a particularly low resistance portion in the battery can body, the location where oxygen gas was generated during overcharging was dispersed throughout the positive electrode. Since it also occurred inside the positive electrode mixture, it can be predicted that it has reached the negative electrode side due to the presence of dissolved oxygen in the electrolyte solution, resulting in suppression of hydrogen gas generation in the negative electrode.

  Furthermore, the battery No. 5 and battery no. 8, the graphite on the side contacting the inside of the battery can body of the positive electrode mixture pellet is reduced, and the graphite of the positive electrode pellet on both ends of the can body, which is a particularly low resistance portion in the battery can body, is reduced. Since the resistance was increased, oxygen gas generation sites during overcharge were dispersed throughout the positive electrode, and also occurred inside the positive electrode mixture. Therefore, it can be predicted that the generation of hydrogen gas in the negative electrode was suppressed as dissolved oxygen in the electrolyte.

  On the other hand, battery no. 11 to battery no. In No. 13, the graphite content on the side of the positive electrode pellet in contact with the inside of the battery can body similarly included, the resistance was not changed, and oxygen gas generation sites during overcharging were concentrated on the inside of the battery can body. It is considered that dissolved oxygen hardly exists in the liquid, and the hydrogen gas generation of the negative electrode could not be suppressed.

  Battery No. 11, Battery No. 14 and battery no. 15, the graphite content contained in the positive electrode pellets at both ends of the can body, which is a particularly low resistance portion even inside the battery can body, is the same as before, and there was no change in the resistance of the low resistance portion. Since it was concentrated and bubbled, it was difficult to exist in the electrolyte solution, and it was considered that the generation of hydrogen gas in the negative electrode could not be suppressed.

  Battery No. In No. 16, the graphite content contained in the positive electrode pellets at both ends of the can body, which is a particularly low-resistance portion even inside the battery can body, increased from the conventional level, and the resistance at the low-resistance portion was further reduced. Since the reaction was concentrated and bubbled, it was unlikely to be present in the electrolyte solution, and it was thought that the generation of hydrogen gas in the negative electrode could not be suppressed.

  Battery No. Battery No. 11 12 to Battery No. The reason for the low liquid leakage rate of No. 16 is considered to be that the hydrogen gas generation reaction itself on the negative electrode side has become somewhat mild because the resistance as a battery has increased as seen in the decrease in the discharge rate.

  As described above, the present invention is useful for alkaline batteries that improve safety during reverse connection.

1 Positive electrode can body 2 Positive electrode 2-A Positive electrode pellet A
2-B Positive electrode pellet B
2-C Positive electrode pellet C
2-D Positive electrode pellet D
3 Negative electrode 4 Separator 5 Sealing body 6 Negative electrode current collector 7 Negative electrode terminal board 8 Exterior label 9 Assembly sealing body

Claims (6)

In a bottomed cylindrical positive electrode can body, a hollow cylindrical positive electrode, a negative electrode disposed in a hollow portion of the positive electrode, a separator disposed between the positive electrode and the negative electrode, and an alkaline electrolyte, A contained alkaline battery,
An alkaline battery having a high resistance portion on at least a part of the outer peripheral surface of the positive electrode.   The alkaline dry battery according to claim 1, wherein the positive electrode includes a positive electrode active material and a conductive agent, and the high resistance portion has a smaller amount of the conductive agent than other portions of the positive electrode.   The alkaline dry battery according to claim 1 or 2, wherein the high resistance portion of the outer peripheral surface is 50% or less of the entire positive electrode.   The alkaline dry battery according to any one of claims 1 to 3, wherein the high resistance portion is disposed at a site on a side in contact with the positive electrode can body.   The alkaline dry battery according to any one of claims 1 to 3, wherein the high resistance portion is at least one of a portion on the opening side and a portion on the bottom side of the positive electrode can body.   The positive electrode is composed of a plurality of hollow cylindrical positive electrode pellets filled in a stack in the positive electrode can body, and the conductive agent amount of the pellets located on the opening side and the bottom side of the positive electrode can body is the conductivity of the pellets at other positions. The alkaline dry battery according to claim 5, wherein the amount is less than the amount of the agent.