JP2008140748A - Manganese dry battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manganese dry battery having high leakage resistance and high discharge capacity. <P>SOLUTION: An electric capacity ratio of zinc contained in an anode zinc can 3 of a manganese dry battery equipped with an outer package label 9 of heat-shrinkable resin, to manganese dioxide contained in a cathode mixed agent 6, is to be 2.24 or more and 4.00 or less. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a manganese dry battery, and more particularly to a manganese dry battery including a protective member that covers an outer peripheral surface of a negative electrode zinc can.

  2. Description of the Related Art Conventionally, manganese dry batteries include a type in which a negative electrode zinc can containing a power generation element is sealed and a heat-shrinkable resin exterior label is wound around the outer periphery of the negative electrode zinc can.

  The negative electrode zinc can used for a manganese dry battery has the function of a negative electrode and a container. For this reason, as the discharge reaction proceeds, zinc is consumed, the thickness of the side surface of the negative electrode zinc can becomes thin, and a hole may be partially opened.

  In the case of a manganese dry battery equipped with a heat-shrinkable resin exterior label, the electrolyte leaked from the open hole in the negative electrode zinc can damages the exterior label or travels between the negative electrode zinc can and the exterior label. In some cases, the battery leaks out of the battery.

In contrast, conventionally, a metal container is disposed on the outer periphery of the negative electrode zinc can, and then the outer label is wound, or the thickness is 0.2 to 1 so as to have electrolyte resistance and impact resistance. A configuration using a thick exterior label of 5 mm is disclosed. (See Patent Documents 1 and 2)
JP-A-6-318451 JP 2006-19091 A

  However, in the conventional configurations shown in Patent Documents 1 and 2, it is necessary to use the above-described metal container or thick exterior label in order to ensure the leakage resistance. This is because, for example, in manganese dry batteries whose outer dimensions are determined by JIS, it is necessary to use a negative electrode zinc can whose outer diameter is reduced by the amount of a metal container or a thick outer label, thereby increasing the discharge capacity. It was obstructing to plan.

  This invention is made | formed in view of this point, The place made into the objective is to provide the manganese dry battery which has high liquid-proof property and high discharge capacity.

  The manganese dry battery of the present invention includes a bottomed cylindrical negative electrode zinc can, a positive electrode mixture that is housed in the negative electrode zinc can and contains manganese dioxide, carbon powder, and an electrolyte, and the negative electrode zinc can and the positive electrode mixture. And a protective member that covers the outer peripheral surface of the negative electrode zinc can, and the electric capacity ratio of zinc contained in the negative electrode zinc can and manganese dioxide contained in the positive electrode mixture is 2 .24 to 4.00.

  The manganese dry battery of the present invention has an electric capacity ratio of zinc contained in the negative electrode zinc can to manganese dioxide contained in the positive electrode mixture (hereinafter simply referred to as electric capacity ratio) of 2.24 or more and 4.00 or less. Since it has a sufficient amount of zinc with respect to manganese, as the discharge reaction proceeds, even if zinc is consumed and the thickness of the side surface of the negative electrode zinc can thins, it is possible that holes will partially open. Without leaking easily. Therefore, since it is not necessary to use the above-mentioned metal container or a thick exterior label, a negative electrode zinc can having a larger outer diameter than that of the conventional one can be used, and the capacity can be increased.

  In the manganese dry battery according to the embodiment of the present invention, the electric capacity ratio of zinc contained in the negative electrode zinc can to manganese dioxide contained in the positive electrode mixture is set to 2.24 or more and 4.00 or less. This electric capacity ratio is a ratio calculated from the theoretical capacity.

  When the electric capacity ratio is less than 2.24, leakage occurs before the battery is used up, and when it is larger than 4.00, the amount of the negative electrode is excessive, so the filling amount of the positive electrode is reduced, and a good discharge capacity is obtained. Cannot be obtained.

  More preferably, the capacitance ratio is 2.40 or more and 4.00 or less. In this way, there is almost no risk of leakage even if the battery is loaded into the device and used, and if the user forgets to turn off the switch and is in an overdischarge state for a long time.

  Further, the weight ratio of manganese dioxide to carbon powder is preferably 4.0 or more. By doing so, the positive electrode mixture becomes hard, and the mechanical strength of the battery can be maintained even if a thin negative electrode zinc can is used. If it is less than 4.0, the carbon powder is relatively increased, the positive electrode mixture becomes soft, and the mechanical strength of the battery may be lowered.

  A heat-shrinkable resin film having a thickness of 0.03 mm or more and 0.15 mm or less may be used for the protective member. If it does in this way, the negative electrode zinc can of the outer diameter larger than before can be used, and high capacity | capacitance can be achieved. Since the protection member is printed and the printed protection member is often called an exterior label, the protection member is hereinafter referred to as an exterior label.

  When the thickness of the outer label is less than 0.03 mm, the strength is insufficient and the breakage easily occurs, and when it is thicker than 0.15 mm, the negative electrode zinc can 3 having a substantially larger outer diameter than conventional cannot be used. A significant increase in discharge capacity cannot be obtained.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a front view of a cross section of a part of an AA manganese dry battery R6 according to an embodiment including an exterior label 9.

  A positive electrode mixture 6 is accommodated in a bottomed cylindrical negative electrode zinc can 3 via a separator 7. The negative electrode zinc can 3 is closed by a zinc plate in which only one of the two cylindrical openings is open and the other is the bottom. On the open side of the negative electrode zinc can 3, the paper 5 is placed on the positive electrode mixture 6, and the sealing body 2 closes the opening of the negative electrode zinc can 3 on the upper side.

  As the positive electrode mixture 6, a mixture of manganese dioxide as an active material, carbon powder such as acetylene black as a conductive material, and a zinc chloride aqueous solution to which a small amount of ammonium chloride is added as an electrolytic solution is used.

  As manganese dioxide, it is preferable to use electrolytic manganese dioxide that can provide a high discharge capacity. However, according to the present invention, sufficient discharge performance can be obtained as compared with the conventional one. Or chemical manganese may be used as appropriate.

  The negative electrode zinc can 3 preferably has high mechanical strength and excellent corrosion resistance, and is preferably made of a zinc alloy to which lead, manganese, magnesium, indium or the like is added.

  As the separator 7, a kraft paper coated with a paste obtained by dissolving a crosslinked starch and a binder mainly composed of vinyl acetate in an alcohol solvent and dried is used. And the separator 7 is arranged so that the application surface may face and contact the negative electrode zinc can 3. A carbon rod 4 obtained by sintering carbon powder is inserted in the central portion of the positive electrode mixture 6. A bottom paper 8 is disposed between the bottom of the positive electrode mixture 6 and the bottom of the negative electrode zinc can 3 to ensure insulation. That is, the separator 7 is disposed so as to cover the inner peripheral surface of the cylindrical portion of the negative electrode zinc can 3, and the positive electrode mixture 6 is surrounded by the separator 7, the bottom paper 8, and the paper 5.

  A sealing body 2 made of polyolefin resin such as polyethylene or polypropylene or nylon seals the opening of the negative electrode zinc can 3. The sealing body 2 is fastened by the outer peripheral edge portion of the positive electrode terminal plate 1 fitted to the top of the carbon rod 4 and the caulking portion of the open end portion of the negative electrode zinc can 3.

  A heat shrinkable resin exterior label 9 is adhered to the outer peripheral surface of the negative electrode zinc can 3 in order to ensure electrical insulation from the outside. The exterior label 9 is made of a heat-shrinkable resin film containing at least one selected from the group consisting of polyethylene, polyvinyl chloride, polystyrene, and polyethylene terephthalate. And the negative electrode zinc can 3 is directly covered by carrying out the heat shrink of the whole heat-shrinkable resin film with a hot air. The exterior label 9 becomes the outermost layer of the cylindrical portion of the dry battery.

  The heat-shrinkable resin film has a cylindrical shape with end faces bonded together, and a negative electrode zinc can 3 in which a power generation element is housed and sealed is inserted, and the heat-shrinkable resin film is cylindrically shrunk with hot air. The entire conductive resin film may be heat shrunk.

  In consideration of environmental problems, the heat-shrinkable resin film is preferably polystyrene, polyethylene, or polyethylene terephthalate.

  In the present embodiment, the electric capacity ratio between zinc contained in the negative electrode zinc can 3 and manganese dioxide contained in the positive electrode mixture 6 is set to 2.24 or more and 4.00 or less.

  The electric capacity ratio was calculated by the following method.

  The positive electrode is obtained by multiplying the weight of the active material manganese dioxide contained in the positive electrode mixture 6 by the theoretical electric capacity per unit weight (0.308 Ah / g). For example, when 9 g of the positive electrode mixture 6 contains 45% of electrolytic manganese dioxide whose purity of manganese dioxide is 91%, the following formula is used.

9 × 0.45 × 0.91 × 0.308 = 1.135 (Ah)
In the negative electrode, the side surface (cylindrical portion) of the negative electrode zinc can 3 facing the positive electrode mixture 6 corresponds to the active material, the outer diameter of the negative electrode zinc can 3, the thickness of the side surface, and the height of the positive electrode mixture 6 (鍔The volume is calculated according to the paper 5 and the bottom paper 8), multiplied by the zinc density (7.14 g / cubic centimeter) and converted to the weight, and then the zinc purity of the negative electrode zinc can 3 and its unit weight Is multiplied by the theoretical electric capacity of (0.820 Ah / g). For example, when the positive electrode mixture 6 having a height of 38.5 mm is filled in the negative electrode zinc can 3 having an outer diameter of 13.64 mm, a side thickness of 0.3 mm, and a zinc purity of 99.5%, Calculated by the formula.

(13.64 / 2 × 13.64 / 2-13.04 / 2 × 13.04 / 2) × 3.14 × 38.5 / 1000 × 7.14 × 0.995 × 0.820 = 2. 818 (Ah)
Therefore, the capacitance ratio in the above example is obtained by the following equation.

  2.818 / 1.135 = 2.483

  Examples of the present invention will be described in detail below as experimental examples, but the present invention is not limited to the following examples.

<Experimental example 1>
In the manganese dry battery of the present embodiment shown in FIG. 1, the experiment number No. having the electric capacity ratio of the values shown in Table 1 by varying the thickness of the side surface of the negative electrode zinc can 3 and the weight ratio of manganese dioxide to the carbon powder. . Batteries with a total of 15 levels of 1-15 were produced. At this time, the thickness of the heat-shrinkable resin film exterior label 9 made of polystyrene of each battery was 0.03 mm, the outer diameter of the negative electrode zinc can 3 was φ13.64, and was common to all.

  In this experiment, in order to clarify the effect of the present embodiment in the electric capacity ratio, as a major factor that determines the electric capacity, the thickness of the side surface of the negative electrode zinc can 3 (= the weight of zinc) and the positive electrode mixture 6 The experiment was conducted in a binary manner by changing the weight ratio of manganese dioxide to the carbon powder.

  Electrolytic manganese dioxide having a purity of 91% was used for manganese dioxide, and acetylene black was used for carbon powder.

  As an electrolytic solution, an aqueous solution containing 2% by weight of ammonium chloride and 30% by weight of zinc chloride was used, and a predetermined amount was mixed according to the weight ratio of manganese dioxide to the carbon powder. Was filled in the negative electrode zinc can 3 in which the separator 7 and the bottom paper 8 were in close contact with the inner surface.

  The negative electrode zinc can 3 was a zinc alloy containing 0.4% lead, and the can was made by a known method using a zinc alloy having a purity of 99.5%.

  Next, evaluation of the battery obtained with these will be described.

(Evaluation 1) Mounting Leakage Test Using Flashlight Load 10 batteries of each experiment number obtained above into 5 commercially available flashlights (using BF-187 made by Matsushita Electric, 2 AA batteries) Then, it was turned on for 30 minutes per day and repeated every day. When each flashlight could not be turned on, each battery was taken out from the flashlight to check for leakage, and the number of leaked batteries was recorded. The leakage is a phenomenon in which the electrolyte leaks out of the battery.

(Evaluation 2) Mounting Over-Discharge Leakage Test Using Flashlights 10 batteries of each experimental number obtained above, 5 commercially available flashlights (using Matsushita Electric BF-187, 2 AA batteries) The battery was left on for 1 month without turning off the light even if it could not be lit. After that, each battery was taken out and checked for leakage, and the number of leaked batteries was recorded.

(Evaluation 3) Discharge test Each battery obtained above was discharged with a load of 3.9Ω. The time required to reach a final voltage of 0.9 V at this time was measured.

  These results are shown in Table 1.

  In the mounting leak test using the flashlight of evaluation 1, No. The batteries Nos. 1, 2, 6-8, and 11-15 have an electric capacity ratio of 2.24 or more, and the negative electrode electric capacity is sufficient with respect to the positive electrode electric capacity. None of the 10 batteries leaked. On the other hand, in the experiment number having an electric capacity ratio of less than 2.24, one or more batteries out of 10 leaked.

  Since the mounting overdischarge leakage test using the flashlight of evaluation 2 is a test under severe conditions, No. 2 having an electric capacity ratio of 2.40 or more. The batteries Nos. 1, 6-8, and 11-14 did not leak because the negative electrode capacity was more sufficient than the positive electrode capacity. In 2 and 15, 1 out of 10 leaked. In addition, No. The electric capacity ratio of the batteries Nos. 2 and 15 is 2.24 or more but less than 2.40.

  In the discharge test of Evaluation 3, it can be evaluated that the discharge sustainability is excellent if the discharge duration is 85 minutes or more. No. All the batteries of 1-15 have a duration longer than 85 minutes, but especially when the electric capacity ratio approaches 4.0 as in the case of 11 batteries, it becomes difficult to balance the leakage resistance characteristics and the discharge characteristics, Since an excessive negative electrode capacity causes a shortage of the positive electrode capacity and it is difficult to obtain a substantial effect of increasing the capacity, the electric capacity ratio is preferably 4.0 or less.

  In the above evaluation, it is practically required that all 10 batteries do not leak under the conditions of evaluation 1. However, since the condition of evaluation 2 is a severe condition, there is no practical problem even if the liquid leaks up to 2 out of 10. However, since it is preferable that all 10 batteries do not leak even under the condition of Evaluation 2, the electric capacity ratio is preferably 2.40 or more.

  Further, if the capacitance ratio exceeds 4.0, it is difficult to process in the manufacturing process, and it is necessary to increase the amount of zinc in the negative electrode zinc can 3 which is the most expensive among the constituent members. It is not preferable.

<Experimental example 2>
Using the same material as in Experimental Example 1, the thickness of the heat-shrinkable resin film exterior label 9 made of polystyrene, the outer diameter of the negative electrode zinc can 3, and the electric capacity ratio were variously changed to the values shown in Table 2. No. similar to that of the dry battery shown in FIG. A 16-27 manganese dry battery was prepared. No. In 16-27, the outer diameter of the batteries was set to a common φ13.7.

  In Experimental Example 2, in order to keep the electric capacity of the negative electrode substantially constant, the thickness of the negative electrode zinc can 3 was made constant and only the outer diameter was changed. The fluctuation of the electric capacity ratio can be considered to be mainly due to the weight ratio of manganese dioxide to the carbon powder of the positive electrode mixture 6.

  These results are shown in No. 1 of Experimental Example 1. 6-10 cells are shown together in Table 2 for comparison.

  In the mounting leak test using the flashlight of evaluation 1, No. The batteries of 9, 10, 20, and 25 have an electric capacity ratio of less than 2.24, and the negative electrode electric capacity is insufficient with respect to the positive electrode electric capacity. A leaked battery was found. However, batteries having an electric capacity ratio of 2.24 or more did not leak.

  In the mounting overdischarge leakage test using the flashlight of evaluation 2, the electrical capacity ratio is less than 2.40. In the batteries of 9, 10, 19, 20, 24, and 25, since the negative electrode capacity was insufficient with respect to the positive electrode capacity, there was a battery that leaked due to an opening in the negative electrode zinc can 3 in an overdischarged state. It was seen. However, as described above, the condition of evaluation 2 is a severe condition, so that practically no leakage of 2 liquids out of 10 is acceptable. 19 and 24 are determined to be acceptable levels.

  In the discharge test of Evaluation 3, No. 1 using a heat-shrinkable resin film having a thickness of the outer packaging label 9 of 0.03 mm to 0.15 mm. In the batteries of 6-10 and 16-25, the negative electrode zinc can 3 having an outer diameter larger than that of the conventional one can be used, and it can be evaluated that all the discharge sustainability is excellent.

  However, No. 1 using a heat-shrinkable resin film having a thickness of the outer label 9 of 0.20 mm. In the batteries of 26 and 27, the discharge duration was 85 minutes or less, and it could not be said that the discharge sustainability was excellent.

  Although the result of the experiment is not shown, if the thickness of the exterior label 9 is less than 0.03 mm, the mechanical strength is insufficient, and it is easily damaged and is not practical.

<Experimental example 3>
When the thickness of the side surface of the negative electrode zinc can 3 is reduced, the mechanical strength of the negative electrode zinc can 3 decreases, but the mechanical strength decreases due to the hardness of the positive electrode mixture 6 housed in the negative electrode zinc can 3. Therefore, the effect of the weight ratio of the carbon powder and manganese dioxide in the positive electrode mixture 6 on the impact resistance of the dry battery was evaluated as No. 1 in Experimental Example 1. It investigated using the battery of 6-10. As a method for checking, a method was adopted in which the battery side was dropped from a height of 1 m, the exterior label 9 was then removed, and the negative electrode zinc can 3 was visually checked for dents.

  No. When 5 batteries of 6-10 were dropped as described above, no. In No. 6, the incidence of dents was 20%. 7-10 was 0%.

  This result is because the mechanical strength of the battery depends on the mixing ratio of hard manganese dioxide constituting the positive electrode mixture 6 and soft carbon powder such as acetylene black. By making the amount of hard manganese dioxide relatively large so that the weight ratio of manganese dioxide to carbon powder is 4.0 or more, a dry battery having high impact resistance can be obtained. In addition, even if the incidence rate of dents is about 20%, it is considered that the mechanical strength is practically sufficient. Moreover, if the side surface of the exterior label 9 or the negative electrode zinc can 3 is thick, the impact resistance is improved.

  As described above, the manganese dry battery of the present invention has a liquid leakage resistance and a high discharge capacity, and thus can be applied to a power source of a flashlight, a portable electronic device, or the like.

It is the figure which made a part of manganese dry battery R6 concerning the embodiment of the present invention a section.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Positive electrode terminal board 2 Sealing body 3 Negative electrode zinc can 4 Carbon rod 5 Paper 6 Positive electrode mixture 7 Separator 8 Bottom paper 9 Exterior label

Claims (5)

A bottomed cylindrical negative electrode zinc can,
Housed in the negative electrode zinc can, a positive electrode mixture containing manganese dioxide, carbon powder and an electrolyte solution;
A separator disposed between the negative electrode zinc can and the positive electrode mixture;
A protective member covering the outer peripheral surface of the negative electrode zinc can,
A manganese dry battery, wherein an electric capacity ratio of zinc contained in the negative electrode zinc can and manganese dioxide contained in the positive electrode mixture is set to 2.24 or more and 4.00 or less.   2. The manganese dry battery according to claim 1, wherein the electric capacity ratio is set to 2.40 or more and 4.00 or less.   The manganese dry battery according to claim 1, wherein a weight ratio of the manganese dioxide to the carbon powder is 4.0 or more.   The manganese dry battery according to any one of claims 1 to 3, wherein the protective member is a heat-shrinkable resin film having a thickness of 0.03 mm or more and 0.15 mm or less.   5. The manganese dry battery according to claim 1, wherein the protective member is disposed in an outermost layer and directly covers an outer peripheral surface of the negative electrode zinc can. 6.

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