JP4804765B2 - Square air battery - Google Patents

Description

  The present invention relates to a rectangular air battery excellent in leakage resistance.

  The button-type air battery is used as a driving power source for small hearing aids, small pagers, and the like. Compared with other batteries of the same size, for example, silver oxide batteries, this air battery can be filled with more zinc as a negative electrode active material because it does not require a bulky positive electrode active material. Therefore, there is an advantage that the battery capacity is large. On the other hand, the button-type air battery has a drawback that the current that can be drawn is small. Because of these drawbacks, it is difficult to use as a drive power source for small electronic devices such as portable electronic devices and small audio devices.

  As a means for increasing the current that can be drawn from the button-type air battery, a method of increasing the battery size can be considered. However, there is a problem that simply increasing the battery size does not fit within the storage volume given to the battery of a small electronic device.

Two more countermeasures can be considered for such a problem. The first countermeasure is to reduce the internal resistance in order to increase the current that can be drawn. The second countermeasure is a method of increasing the current that can be drawn by effectively using the volume given to the battery in the small electronic device by using a rectangular shape instead of the button shape. This is a structure in which a positive electrode case, a negative electrode sealing case, and an insulating gasket are formed in a square shape, and the positive electrode case and the negative electrode sealing case are sealed via an insulating gasket (Patent Document 1).
Japanese translation of PCT publication No. 2002-532858

The square air battery has a structure composed of a straight portion and a corner portion as compared with a button-type battery. Therefore, the following problems occur at the time of sealing.
Since the negative electrode case is formed by drawing, uneven thickness and work hardening occur in the corner portion. For this reason, the corner portion of the negative electrode case has higher mechanical strength than the straight portion. Due to the difference in mechanical strength between the corner portion and the straight portion, when sealing with caulking in accordance with the mechanical strength of the corner portion, the straight portion cannot withstand the sealing pressure, and the side wall portion of the straight portion is inward. It buckles and deforms (FIG. 11). This causes two more problems.

  The first problem is that a gap is formed between the side wall portion of the straight portion of the negative electrode case and the insulating gasket, and the liquid leaks from this gap. The second problem is that a gap is formed between the outer peripheral edge of the air electrode and the wall surface of the positive electrode case, the contact between the two becomes worse, and the internal resistance of the battery is increased.

  SUMMARY OF THE INVENTION The present invention solves such conventional problems, and an object of the present invention is to provide a rectangular air battery that has excellent liquid leakage resistance and can suppress an increase in internal resistance.

In order to solve the above problems, the present invention provides a rectangular positive electrode case in which an air diffusion paper, a water repellent film, an air electrode, and a separator are accommodated in that order on a bottom surface having air holes, and from the opening to the inside and outside of the side wall. A rectangular negative electrode sealing case in which a cylindrical insulating gasket having a substantially U-shaped cross-section to be coated is mounted and a negative electrode containing an electrolytic solution is accommodated, and an opening is combined toward the bottom of the positive electrode case, and A square air battery in which both cases are sealed by caulking the open end of the positive electrode case to the outer periphery of the negative electrode sealing case via the insulating gasket, and corresponds to at least the four side surfaces of the case on the bottom surface of the positive electrode case and a rib protruding inwardly disposed, and so by the ribs through the separator support inner surface lower end portion of the insulating gasket, the position provided with the ribs prior to Than the inner surface lower end portion of the insulating gasket on Square air battery in the center side of the bottom surface.

  In the rectangular air battery of the present invention, the lower end portion of the inner side surface of the insulating gasket is supported by the rib of the positive electrode case via the separator, so that the side wall portion of the negative electrode case is prevented from being deformed inward. By doing so, the side wall portion of the negative electrode case and the insulating gasket can be brought into close contact with each other, and leakage can be prevented. Moreover, since the deformation | transformation of the air electrode accompanying a deformation | transformation of the side wall part of a negative electrode case is lose | eliminated and the contact between the outer periphery part of an air electrode and the wall surface of a positive electrode case can be maintained, the raise of internal resistance can also be suppressed. Therefore, it is possible to provide a high-quality square air battery having excellent liquid leakage resistance.

The square air battery of the present invention has air holes on the bottom surface of the positive electrode case. Air diffusion paper, a water repellent film, an air electrode, and a separator are stacked and accommodated in this order on the bottom surface of the positive electrode case. A cylindrical insulating gasket having a substantially U-shaped cross section is mounted so as to cover the opening of the negative electrode case from the inside and outside of the side wall. A negative electrode case containing an electrolytic solution is accommodated in the negative electrode case to which the insulating gasket is attached. The bottom surface of the insulating gasket attached to the negative electrode case is combined so as to face the inner bottom surface of the positive electrode case. The open end portion of the positive electrode case seals the outer peripheral portion of the negative electrode case by caulking through the insulating gasket. On the bottom surface of the positive electrode case, ribs that protrude toward the inside of the case are provided corresponding to at least four side surfaces of the case. The rib supports the lower end of the inner surface of the insulating gasket via the separator. The position where the rib is provided is closer to the center of the bottom surface than the lower end of the inner surface of the insulating gasket. The rib protruding to the inside of the case may constitute one continuous square corresponding to the outer shape of the bottom surface of the positive electrode case.

  Here, the air diffusion layer is a layer for diffusing the air taken in from the air holes, and also has a function of absorbing the electrolyte and preventing leakage. The water repellent film is a film for preventing the electrolyte from leaking out of the battery. The air electrode is a positive electrode and includes a catalyst for reducing oxygen in the air.

  In a preferred embodiment of the present invention, a water repellent film, an air electrode, and a separator are sandwiched between the rib of the positive electrode case and the bottom surface of the insulating gasket.

  The rib provided on the positive electrode case serves as a stopper that prevents the bottom surface of the insulating gasket from sliding into the battery when sealing with caulking. Furthermore, the side wall portion of the negative electrode case can be prevented from falling inward. As a result, the side wall portion of the negative electrode case and the insulating gasket are brought into close contact with each other, and the generation of a gap between them is suppressed. Further, by suppressing the deformation of the bottom surface of the insulating gasket, it is possible to suppress the deformation of the water repellent film, the air electrode, and the separator sandwiched between the bottom surface of the insulating gasket and the inner bottom surface of the positive electrode case.

  In a preferred embodiment of the present invention, the cross-sectional shape of the rib of the positive electrode case is a ratio of the height dimension b to the width dimension a of the protruding part, that is, the protruding part inward from the bottom surface of the positive electrode case b / a is 0.1 to 2.5.

  In a preferred embodiment of the present invention, the ratio d / c of the thickness d of the side wall of the negative electrode case to the thickness c of the side wall of the positive electrode case is 1.1 to 2.5. When the thickness of the side wall of the negative electrode case increases, the amount of negative electrode that can be filled in the battery decreases, and therefore a more preferable range of d / c is 1.1 to 2.0.

  In a further preferred embodiment of the present invention, the insulating gasket has a rounded bottom end (hereinafter abbreviated as a rounded portion), and an air electrode is interposed between the rounded portion and the inner wall of the positive electrode case. The outer periphery is sandwiched. The end surface of the outer peripheral edge of the metal net serving as the current collector of the air electrode is in electrical contact with the inner surface of the side wall of the positive electrode case. Thus, the electrical contact between the positive electrode case and the air electrode is ensured by intentionally letting the outer peripheral edge of the air electrode into the rounded portion of the insulating gasket. Further, the outer peripheral edge portion of the air electrode and the separator is submerged in the rounded portion of the insulating gasket, so that deformation of these at the time of sealing is also suppressed. By doing so, the bottom surface portion of the insulating gasket and the laminated water-repellent film, the air electrode, and the separator can be in close contact with each other, and an increase in the internal resistance of the battery can be suppressed.

  In a further preferred embodiment of the present invention, the protruding rib of the positive electrode case has a rounded protruding tip. As a result, the stress applied to the contact point between the rib tip, the water repellent film, and the air electrode is distributed on the rounded portion of the rib on average, and the rib, the water repellent film, and the air electrode are sealed during sealing. It is possible to prevent the water repellent film or the air electrode from being broken due to excessive pressure applied to the contact.

  In a further preferred embodiment of the present invention, the bottom surface of the positive electrode case has a step, a portion inside the rib protrudes downward from a portion outside the rib, and the step is formed on the bottom portion of the case. Same as or smaller than thickness. In such a configuration, the thickness of the air diffusion paper can be increased by the level difference. As a result, the air supplied from the air holes can be diffused almost uniformly over the entire surface of the air electrode, and thus the heavy load discharge characteristics can be improved.

  In a further preferred embodiment of the present invention, side wall portions corresponding to the four sides of the square air battery of the negative electrode case, the insulating gasket and the positive electrode case have loose roundness protruding outward. Therefore, the stress in the surface direction of the gasket, that is, the direction orthogonal to the sealing pressure, generated by the sealing pressure applied in the axial direction of the case can be made substantially uniform over the entire circumference of the gasket. Thereby, leakage resistance can be improved.

  In a further preferred embodiment of the present invention, the rib exists only at portions corresponding to the four side surfaces of the positive electrode case, that is, at positions parallel to the side surfaces, and does not exist inside the corner portion of the bottom surface of the positive electrode case. As a result, similar to the above example, the stress applied in the gasket surface direction can be made substantially uniform over the entire circumference of the gasket. Thereby, leakage resistance can be improved.

Stainless steel or iron can be used for the base material of the positive electrode case and the negative electrode case.
The negative electrode case is, for example, a clad material in which copper metal is bonded to a base material, and the surface of the base material is plated with nickel metal. Copper metal is disposed on the inner surface of the case, and nickel metal plating is disposed on the outer surface of the case. Furthermore, what has tin metal plated on copper metal can also be used.

  As the insulating gasket, a thermoplastic polymer having alkali resistance can be used. For example, a polyolefin resin such as a polyethylene resin or a polypropylene resin may be used, and a polyamide resin such as nylon may be used.

  As the electrolytic solution, a gelled electrolytic solution obtained by mixing an aqueous solution containing potassium hydroxide (hereinafter abbreviated as KOH) and zinc oxide (hereinafter abbreviated as ZnO) and a gelling agent is usually used.

  The KOH concentration range is preferably 28 to 45 wt%. The concentration of ZnO for suppressing self-discharge of zinc as the negative electrode active material may be dissolved in the KOH aqueous solution until it is saturated. An organic anticorrosive may be dissolved in the aqueous KOH solution in order to suppress the generation of hydrogen gas. Examples of the organic anticorrosive include fluoroalkyl polyoxyethylene. Examples of the gelling agent include carboxymethyl cellulose, polyvinyl alcohol, polyethylene oxide, polyacrylic acid, sodium polyacrylate, chitosan gel, etc., and those having a different degree of polymerization, degree of crosslinking, and molecular weight. You may use what mixed 2 or more types of them.

  The zinc alloy powder serving as the negative electrode active material may contain at least one of Al, Bi, In, Ca, Pb, and Sn in a range of 50 to 1000 ppm as a metal species having a high hydrogen overvoltage. Two or more of these metal species may be included. Other metal electrodes such as an iron electrode, an aluminum electrode, a calcium electrode, and a magnesium electrode can be used for the negative electrode. In that case, an electrolytic solution suitable for those electrodes is used.

As separators, vinylon nonwoven fabric, cellulose homogeneous membrane, polyethylene microporous membrane or polypropylene microporous membrane with hydrophilic treatment, sheets laminated with vinylon nonwoven fabric and cellulose homogeneous membrane, vinylon nonwoven fabric and polyethylene microporous membrane with hydrophilic treatment, Although the sheet | seat which laminated the polypropylene microporous film is mentioned, it is not limited to these.
Examples of the present invention will be described in detail below.

FIG. 1 is a front view showing a section of a rectangular air battery according to an embodiment of the present invention. FIG. 2 is a plan view thereof. FIG. 3 is a bottom view.
The positive electrode case 1 and the negative electrode sealing case 2 are rectangular air batteries sealed through a polypropylene resin gasket 3 as an insulating gasket interposed therebetween. The positive electrode case 1 includes a bottom portion 11 and four side walls 12 that are continuous with the bottom portion 11 and are continuous with each other, and has an opening that is partitioned by these side walls. The corner portion 14 that connects the side walls 12 of the positive electrode case 1 is curved. Similarly, the negative electrode sealing case 2 includes a bottom portion 21 and four side walls 22 connected to the bottom portion and connected to each other, and has an opening partitioned by these side walls. The side wall of the negative electrode sealing case 2 has a shoulder portion 25. A corner portion 24 that connects the side walls 22 of the case 2 is curved. The gasket 3 includes four outer side walls 32 connected to each other, four inner side walls 33 connected to each other, and a bottom portion 31 connecting the lower ends of the side walls 32 and 33.

  The battery size is, for example, 25 mm long, 35 mm wide, and 3.0 mm thick. The sealing is performed by caulking using a sealing mold installed in a press machine. That is, as described below, the positive electrode case 1 containing the air diffusion paper 4, the water repellent film 5, the air electrode 6, and the separator 7 was combined with the gasket 3 on the side wall 22, and the negative electrode 8 containing the electrolytic solution was contained. The negative electrode sealing case 2 is combined with the opening of the negative electrode sealing case facing the bottom of the positive electrode case. This is set in a sealing mold, and the end of the side wall of the positive electrode case 1 is caulked to the side wall 22 of the negative electrode sealing case 2 through the outer side wall 32 of the gasket 3. Thereby, the side wall 32 of the gasket 3 is radially compressed between the end of the side wall 12 of the case 1 and the side wall 22 of the case 2, and further, the inner surface of the side wall 12 of the case 1 and the shoulder portion 25 of the case 2 And a liquid-tight seal is obtained between the side wall 12 of the case 1 and the side wall 22 of the case 2. The axial tightening force by the side wall 12 of the case 1 acts so that the end of the side wall 22 of the case 2 compresses the bottom 31 of the gasket 3 toward the bottom of the case 1. As a result, a seal is obtained between the bottom surface of the case 1 and the gasket 3. Further, the axial tightening force by the side wall 12 of the case 1 acts to push the side wall 22 of the case 2 toward the inside of the case and thus push the gasket 3 toward the center of the case 1. However, there is a rib 10 at the bottom of the case 1, and this rib supports the lower end portion on the inner side of the side wall 33 of the gasket 3 via the separator 7 or the like, so that the side wall 22 of the case 2 is deformed inward. The gasket 3 is not displaced inward.

  As shown in FIG. 1, the battery has an air diffusion paper 4 adhered to the positive electrode case 1 and a microporous polytetrafluoroethylene film (hereinafter abbreviated as PTFE film) 5 as a water repellent film. The air electrode 6 and a polyethylene microporous membrane (hereinafter abbreviated as a hydrophilic treated PE microporous membrane) 7 subjected to hydrophilic treatment as a separator are laminated in this order. The outer peripheral edge of the air electrode 6 is in electrical contact with the side wall of the positive electrode case 1. The negative electrode case 2 is fitted with a gasket 3 having a U-shaped cross section. A negative electrode 8 containing an electrolytic solution is filled in the negative electrode case.

  The positive electrode case 1 uses a stainless steel base material whose outer surface is plated with nickel metal. An air hole 9 for taking in air and a rib 10 are provided on the bottom surface of the case. Between the bottom surface of the positive electrode case 1 and the gasket 3, a PTFE film 5, an air electrode 6, and a hydrophilic treatment PE microporous film 7 are sandwiched.

  The rib 10 of the positive electrode case 1 is provided in a convex shape from the bottom to the inside of the battery over the entire circumference at a position equidistant from the side wall of the positive electrode case 1. The gasket 3 is disposed between the rib 10 and the side wall of the positive electrode case 1.

  The negative electrode case 2 is a clad material in which copper metal is bonded to stainless steel as a base material, and the surface of the stainless steel is plated with nickel metal. Copper metal is disposed on the inner surface of the case, and nickel metal plating is disposed on the outer surface of the case.

  An auxiliary sealing layer is interposed between the side wall portion of the positive electrode case 1 and the gasket 3 in order to prevent leakage. The sealing auxiliary layer is formed by applying a sealing agent in which Bron asphalt pitch is dissolved in toluene as a solvent to the gasket 3 and drying it.

The air electrode 6 is produced as follows.
40% by weight of manganese oxide, 30% by weight of activated carbon, 20% by weight of ketjen black (Mitsubishi Chemical Corporation, ketjen black EC) which is a kind of carbon black as a conductive material, and polytetracene as a binder Fluoroethylene powder (hereinafter abbreviated as PTFE powder) 10% by weight is mixed. This mixture is pressure-bonded to a nickel metal plated stainless steel net serving as a current collector, and the air electrode 6 is produced. The end surface of the outer peripheral edge of the metal net serving as the current collector of the air electrode 6 is in electrical contact with the inner surface of the side wall of the positive electrode case 1.

The electrolytic solution is prepared as follows.
An aqueous solution containing 40% by weight of KOH and 3% by weight of ZnO is prepared. Next, 3% by weight of sodium polyacrylate and 1% by weight of carboxymethyl cellulose are mixed with this aqueous solution as a gelling agent to prepare a gelled electrolyte.

The negative electrode 8 containing the electrolytic solution is prepared as follows.
A zinc alloy powder as a negative electrode active material is added to the gelled electrolyte solution in a weight ratio twice as much as that of the gelled electrolyte solution and mixed.
Below, the rib 10 of the positive electrode case 1 is demonstrated concretely.

<< Examples 1-6 >>
A square air battery was manufactured using the ratio b / a (FIG. 4) of the height dimension b to the width dimension a of the protruding portion of the rib 10 of the positive electrode case 1 shown in Table 1 described below. Here, the positive electrode case 1 and the negative electrode case 2 have a thickness of 0.25 mm.

<< Examples 7 to 12 >>
Below, the case where the plate | board thickness of the positive electrode case 1 and the negative electrode case 2 is changed is demonstrated concretely.
The plate thickness of the positive electrode case 1 and the negative electrode case 2 is changed, and the ratio d / c of the side wall thickness d of the negative electrode case 2 to the thickness c of the side wall of the positive electrode case 1 is square as shown in Table 2 described below. An air battery was produced. Here, the dimension ratio b / a of the rib 10 of the positive electrode case 1 was fixed to 0.30.

Example 13
Hereinafter, the case where the rounded portion is provided at the lower end portion of the outer surface of the gasket 3 will be specifically described.
As shown in FIG. 5, a rounded portion 33 </ b> R having a curvature radius of 0.5 mm is provided at the lower end portion of the outer surface of the gasket 3. Other than that, a square air battery in which a rib 10 was provided on the positive electrode case 1 in the same manner as in Example 8 was produced.

Example 14
Hereinafter, the case where the rounded portion is provided at the projecting tip portion of the rib 10 will be specifically described.
As shown in FIG. 6, a rounded portion having a radius of curvature of 0.5 mm was provided at the protruding protruding tip of the rib 10. Other than that, the square air battery similar to Example 8 was produced.

Example 15
Hereinafter, a specific description will be given of a case where there is a step on the bottom surface of the positive electrode case 101 and the bottom surface portion 111a on the inner side of the rib 20 is at a lower position than the bottom surface portion 111b on the outer side of the rib 20.
As shown in FIG. 7, a step of 0.15 mm was provided on the bottom surface of the positive electrode case 101. That is, at the bottom of the case 101, the portion 111a inside the rib 20 protrudes downward by 0.15 mm from the portion 111b outside the rib 20. The thickness of the air diffusion paper 4 was increased according to this step. Other than that, the square air battery similar to Example 8 was produced.

Example 16
Hereinafter, an example in which the side wall portions corresponding to the four sides of the square air battery of the negative electrode case, the insulating gasket, and the positive electrode case have loose roundness protruding outward will be described in detail.
As shown in FIG. 8, the short side 122S has a radius of curvature of 125 mm and the long side 122L has a curvature so that the portions other than the corner of the side wall of the negative electrode case 102 protrude outward in the surface direction of the battery. A rounded portion having a radius of 150 mm was provided. Similarly to the insulating gasket 103 and the corner portion of the side wall of the positive electrode case 201, a rounded portion with a radius of curvature of 125 mm is provided on the short side and a rounded portion with a radius of curvature of 150 mm is provided on the long side. Other than that, the square air battery similar to Example 8 was produced.

Example 17
Below, the case where the rib 10 exists only in a parallel position along the straight line portion on the bottom surface of the positive electrode case and does not exist inside the corner portion on the bottom surface of the positive electrode case will be specifically described.
As shown in FIG. 9, the ribs 40 exist only in parallel positions along the straight line portion of the bottom surface of the positive electrode case 1 </ b> A, and thus along the straight line portion of the side wall 33 of the gasket. Therefore, the ribs 40 are not connected to each other. Except for the above, a rectangular air battery similar to that of Example 8 was produced.

《Comparative example》
A square air battery similar to that in Example 4 was produced except that the rib 10 was not provided on the positive electrode case 1 and the rounded portion was not provided on the outer peripheral side of the bottom surface of the gasket 3.

  About the square air battery of Examples 1-17 and a comparative example, the heat cycle test (henceforth abbreviated as HC test) was done as a high temperature, high humidity preservation test as a liquid leak acceleration test, and confirmation of the internal resistance of a battery.

  15 cells each were used for the high temperature and high humidity storage test. The battery was stored for 3 weeks under conditions of a temperature of 45 ° C. and a relative humidity of 90%, and the battery in which no leakage was observed was further stored for 2 weeks. At this time, the battery in which leakage was observed after storage for 3 weeks ended storage evaluation at 3 weeks. Only the batteries for which leakage was not observed were evaluated for continued storage. As a method for observing leaked liquid, use a magnifying glass for the battery after storage to observe the presence of liquid leakage between the positive electrode case and the insulating gasket and between the negative electrode sealing case and the insulating gasket. Counted the number. As a method for judging leakage, a reagent (for example, cresol red reagent) that changes color with an alkaline electrolyte is sprayed on the surface of the battery, and the presence or absence of a change in the reagent is observed.

Five cells were used for each HC test. The test was conducted for 7 days by repeating a cycle (4 hours in total) of storing in a thermostat at 60 ° C. for 2 hours and then storing in a thermostat at −10 ° C. for 2 hours. In order to confirm electrical contact between the outer peripheral edge of the air electrode and the side wall of the positive electrode case, the internal resistance before and after the test was measured by an alternating current method of 1 kHz. The difference of internal resistance before and after the test was taken as the amount of change, and the average of 5 cells was calculated.
The results are shown in Table 3.

  From the results shown in Table 3, it can be seen that the batteries of Examples 1 to 17 are superior in leak resistance because the number of batteries in which liquid leakage was observed was small as compared with the batteries of Comparative Examples. In addition, when the longitudinal sections of these batteries were observed, the battery of the comparative example had no rib on the positive electrode case, so the bottom of the insulating gasket slipped into the battery, and the side wall of the negative electrode sealing case was inside the battery. It fell down and buckled. There were gaps between the side wall portion of the positive electrode case and the insulating gasket and between the side wall portion of the negative electrode sealing case and the insulating gasket. It is thought that the liquid leaked through these gaps. When further observed, the air electrode and the separator were deformed, and the electrolytic solution also circulated between the outer peripheral edge of the air electrode and the separator and between the air electrode and the positive electrode case. From the appearance of the battery, no leakage from the air holes was observed, but it was assumed that if the evaluation days were extended further, the leakage from the air holes.

  The batteries of Examples 1 to 6 after 3 weeks of storage had a very small number of leaks compared to the batteries of the comparative examples. It can be seen that the leakage resistance is improved by providing a rib in the positive electrode case. When the longitudinal sections of these batteries were observed, in the batteries of Examples 1 and 6 and the battery of the comparative example, a gap was observed between the positive electrode case side wall portion and the insulating gasket side surface portion. The battery of the comparative example had the highest degree of slipping into the battery at the bottom of the insulating gasket and the degree of falling into the battery at the side wall of the negative electrode sealing case. On the other hand, the battery of the example had a smaller degree of slipping into the inside of the battery at the bottom of the insulating gasket and the degree of falling into the battery inside the side wall of the negative electrode sealing case than the battery of the comparative example.

  The amount of change in the internal resistance before and after the HC test increased in the order of the batteries of Examples 2 to 5, the batteries of Examples 1 and 6, and the battery of the comparative example. When the discharge performance of the battery after the HC test was confirmed, the battery of the comparative example was reduced by 90% with respect to the initial capacity, whereas the batteries of Examples 2 to 5 were 10% of the initial capacity. % Decrease. The batteries of Examples 1 and 6 were reduced by 50% with respect to the initial capacity. From this, the ratio b / a of the height dimension b to the width dimension a of the rib of the positive electrode case is preferably 0.1 to 2.5.

  The batteries of Examples 7 to 13 after 3 weeks of storage had a much smaller number of leaks than the batteries of the comparative examples. When the longitudinal sections of the batteries of Examples 7 to 13 were observed, neither sliding of the bottom of the insulating gasket into the battery nor falling of the negative electrode sealing case side wall into the battery was observed.

  The amount of change in internal resistance after the HC test was slightly larger in the battery of Example 7 than in the batteries of Examples 8-12. When the discharge performance was confirmed about the battery after HC test, the battery of Examples 8-12 was a fall within 10% with respect to an initial capacity. In contrast, the battery of Example 7 was observed to be 20% lower than the initial capacity. Therefore, the ratio d / c of the side wall thickness d of the negative electrode sealing case to the side wall thickness c of the positive electrode case is preferably 1.1 to 2.5. Further, when the thickness d of the negative electrode sealing case increases, the amount of negative electrode that can be filled in the battery decreases, and the battery capacity decreases. For this reason, the ratio d / c is preferably 2.0 or less. Therefore, a more preferable range of the ratio d / c is 1.1 to 2.0.

  In the battery of Example 13, no leakage was observed even after 5 weeks. When the vertical cross section of this battery was observed, the outer peripheral edge portion of the air electrode and the separator had entered the gap between the rounded portion of the bottom peripheral portion of the insulating gasket and the side wall portion of the positive electrode case. And no deformation of the separator was observed. The amount of change in internal resistance after the HC test was 0.1Ω. From this, by providing the rounded portion on the outer peripheral portion of the bottom surface of the insulating gasket, it is possible to maintain the electrical contact between the outer peripheral edge portion of the air electrode and the side wall portion of the positive electrode case in addition to the improvement of the leakage resistance. .

  In the battery of Example 14, no leakage was observed even after 5 weeks, and the amount of change in internal resistance after the HC test was as small as 0.2Ω. For this reason, even when the rounded portion is provided at the tip of the rib, the electrical contact between the outer peripheral edge of the air electrode and the side wall of the positive electrode case can be maintained. In addition, when the battery of Example 14 was disassembled and the water-repellent film and the air electrode were observed, the level difference caused by the contact with the ribs was moderate at the locations that were in contact with the rib tips. As a result, the stress applied to the contact between the tip of the rib and the air electrode is distributed on the rounded portion of the rib on average, and excessive pressure is applied to the contact between the rib and the air electrode during sealing, and the air It is possible to prevent the pole from being broken.

  The battery of Example 15 was almost the same as Example 8 in both the leakage rate after 5 weeks and the amount of change in internal resistance after the HC test. However, when the initial discharge performance of the batteries of Example 15 and Example 8 was confirmed, the discharge capacity of Example 15 was increased by 2% compared to Example 8. The reason why the discharge capacity increased in the initial discharge performance is that the diffusion resistance component at the time of discharge decreased due to the improvement of the air diffusion efficiency. For this reason, the heavy load discharge characteristics can be improved by providing a step on the bottom surface of the positive electrode case.

The battery of Example 16 had the smallest leakage rate after 5 weeks and the amount of change in internal resistance after the HC test among all the Examples. Further, the battery of Example 16 was hardened with an epoxy resin and cut along the diagonal of the battery. A longitudinal sectional view thereof is shown in FIG. In a portion that hits the corner portion of the battery, the compression ratio of the portion T between which the insulating gasket 103 is sandwiched between the shoulder portion 125S of the shoulder side wall 122 of the negative electrode case 102 and the side wall 212 of the positive electrode case 201, that is, 100 × ( thickness after compression) / (thickness before compression) is the average of the left T _L and right T _R of longitudinal cross-sectional view shown in FIG. 10 was 40%, respectively.

  Similarly, it cut | disconnected in the center of the short side and long side of a battery, and observed the longitudinal cross-section. That is, the part corresponding to the AA sectional view and the BB sectional view of FIG. 8 was observed. The ratio of the outer side wall of the insulating gasket compressed between the shoulder of the side wall of the negative electrode case and the side wall of the positive electrode case in the same manner as described above was cut at the longitudinal section cut at the center of the long side and at the center of the short side. In the longitudinal section, the average of the left and right sides of the longitudinal section was 40% on average. Therefore, the ratio that the insulating gasket is compressed by the shoulder of the negative electrode case is considered to be uniform throughout the gasket. From this, the stress applied in the direction orthogonal to the axis of the battery after the sealing can be uniformly distributed over the entire circumference of the gasket, and the leakage resistance can be improved.

  In the battery of Example 17, no leakage was observed even after 5 weeks. Further, the amount of change in internal resistance after the HC test was smaller than that in Example 8. Similar to the battery of Example 16, the battery was hardened with an epoxy resin, cut along the diagonal of the battery, and the longitudinal section thereof was observed. In the portion corresponding to the corner portion of the battery, the average of the ratio at which the insulating gasket was compressed by the shoulder portion of the negative electrode case on the left and right of the longitudinal section was 38%. Similarly, it cut | disconnected in the center of the long side of a battery, and the short side, and observed the longitudinal cross-section. The average of the length of the vertical cross-section of the ratio at which the insulating gasket is compressed by the shoulder of the negative electrode case is 38% in the vertical cross-section cut at the center of the long side, and the vertical cross-section cut at the center of the short side. The average of left and right was 38%. Therefore, it is considered that the ratio at which the insulating gasket is compressed by the shoulder of the negative electrode sealing case is uniform throughout the gasket. From this, the stress applied in the direction perpendicular to the axis of the battery after the sealing can be uniformly distributed over the entire circumference of the gasket, and the leakage resistance can be improved.

  In the embodiment, an air battery having a length of 25 mm, a width of 35 mm, and a thickness of 3.0 mm has been described, but the size is not limited thereto.

  In the embodiment, in the square air battery, a rib was provided in the positive electrode case, and the sealing structure related to the ratio of the height dimension to the width dimension of the rib and the ratio of the thickness of the negative electrode sealing case side wall to the thickness of the positive electrode case side wall was described. . Such a sealing structure can be applied to, for example, a rectangular alkaline manganese battery and a rectangular silver oxide battery sealing structure in addition to the rectangular air battery by eliminating the air hole of the positive electrode case, and has excellent liquid leakage resistance. A rectangular battery can be obtained.

  The present invention can provide a high-quality square air battery by providing a rib on the positive electrode case. The prismatic air battery of the present invention can be used not only for small hearing aids and small pagers, but also as a driving power source for small electronic devices such as portable electronic devices and small audio devices.

It is the front view which made a part of square air battery in one example of the present invention a section. It is a top view of the battery. It is a bottom view of the battery. It is an expanded sectional view of the part which has a rib of a positive electrode case. It is the front view which made a part of square air battery in other examples of the present invention a section. It is an expanded sectional view showing other examples of a portion which has a rib of a positive electrode case. It is the front view which made a part of square air battery in other examples of the present invention a section. It is a top view of the square air battery in other examples of the present invention. It is a bottom view of the square air battery in further another example of the present invention. FIG. 10 is a sectional view taken along line 10-10 in FIG. 8. It is a longitudinal cross-sectional view of the conventional square air battery.

Explanation of symbols

1, 1A, 101, 201 Positive electrode case 2, 102 Negative electrode sealing case 3, 103 Gasket 4 Air diffusion paper 5 Water repellent film 6 Air electrode 7 Separator 8 Negative electrode 9 Air hole 10, 20 Rib a Width of rib 10 b Rib 10 C Dimension of the side wall of the positive electrode case 1 d Thickness of the side wall of the negative electrode sealing case 2

Claims (9)

A rectangular positive electrode case containing air diffusion paper, a water repellent film, an air electrode, and a separator in that order on the bottom surface having air holes;
A rectangular negative electrode seal in which a cylindrical insulating gasket having a substantially U-shaped cross section covering from the opening to the inside and outside of the side wall is mounted and a negative electrode containing an electrolyte is accommodated, and the opening is combined toward the bottom of the positive electrode case A case,
A square air battery in which the open end of the positive electrode case is caulked to the outer periphery of the negative electrode sealing case via the insulating gasket, and both the cases are sealed,
The bottom surface of the positive electrode case, a rib protruding inward in response to the four sides of at least the casing, and so as to support the inner surface lower end portion of the insulating gasket through the separator by the rib, the rib Is provided at a position closer to the center of the bottom surface than the lower end of the inner surface of the insulating gasket .   The rectangular air battery according to claim 1, wherein the water repellent film, the air electrode, and a separator are laminated between a rib of the positive electrode case and a bottom surface of the insulating gasket.   3. The square shape according to claim 1, wherein a cross-sectional shape of the rib of the positive electrode case is such that a ratio b / a of a height dimension b to a width dimension a of a protruding portion of a convex shape is 0.1 to 2.5. Air battery.   The square air battery according to any one of claims 1 to 3, wherein a ratio d / c of a side wall thickness d of the negative electrode sealing case to a side wall thickness c of the positive electrode case is 1.1 to 2.5.   5. The insulation gasket according to claim 1, wherein a lower end portion of the outer surface has a roundness, and an outer peripheral edge portion of the air electrode is sandwiched between the rounded portion and the inner side wall of the positive electrode case. Square air battery.   The square air battery according to any one of claims 1 to 5, wherein a protruding tip of the rib has a rounded end.   The bottom surface of the positive electrode case has a step, a portion inside the rib protrudes downward from a portion outside the rib, and the step is equal to or smaller than the thickness of the bottom surface portion of the case. Item 7. The square air battery according to any one of Items 1 to 6.   The square air battery according to any one of claims 1 to 7, wherein the negative electrode case, the insulating gasket, and the positive electrode case have loose rounded portions that protrude from the side walls corresponding to the four sides of the square air battery.   The square air battery according to any one of claims 1 to 8, wherein the rib constitutes one continuous square corresponding to the outer shape of the bottom surface of the positive electrode case.

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