JPS5998479A - Air cell - Google Patents

Abstract

PURPOSE:To make the promotion of a large output attainable in a way of using oxygen gas fed from outside in a highly efficient manner as well as to offer such an air cell as partaking both usability for long hours and storage stability by installing an oxygen selective permeable film in space between an outer can and the air cell via an air diffusion layer. CONSTITUTION:A circular groove forming a concentric circle with another concentric circle, which is to lock an air electrode 1 and a separator 5, is installed in each of gaskets 3 and 4 set up in the air electrode and the separator 5 while an oxygen gas selective permeable film 4 is made into a cylindrical form, then inserted into this groove part and welded together. As the air electrode, the following three layers being unified as one body by pressure are used that 1) a gas permeable water-repellent film layer composed of a polytetraphloroethylene (PTFE) film of 100mum in thickness, having fine holes uniformly distributing an average bore diameter of 10mum, 2) a porous catalytic layer roll-molded after mixing those of platinum 4wt%, active carbon powder 80wt% and PTFE powder 16wt%, and 3) a collector layer composed of a nickel wire mesh. On the other hand, a negative pole collector body 7 consisting of a brass needle is set up in a negative pole flux (black) and top and bottom ends of an outer can are clamped each whereby an air-zinc cell is produced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an air cell equipped with an oxygen gas selectively permeable membrane that permeates oxygen gas and suppresses water vapor permeation.

[Technical background of the invention and its problems]

Air batteries that use metal as a negative electrode active material and oxygen as a positive electrode active material can extract oxygen from the air. Therefore, an air battery can be expected to contain an energy density that is approximately twice as high as that of the 9th battery. However, in order to obtain oxygen from the air, LIc requires an air inflow hole in the battery container, which may prevent water vapor or carbon dioxide from flowing into the battery.
This may cause the moisture inside the battery to leak out. When water vapor flows into the battery, it reduces the concentration of electrolyte, causes local short circuits, causes fluctuations in ball output, and increases internal pressure, causing leakage and rupture. Furthermore, when the electrolyte is alkaline, the composition of the electrolyte changes due to the inflow of carbon dioxide gas.

On the other hand, if moisture leaks from inside the battery in the form of the leakage described above, it can lead to damage not only to the battery but also to peripheral equipment, and if it occurs in the form of water vapor scattering, the electrolyte concentration gradually decreases. If the upper limit is 9, no output will be obtained due to the electrolyte drying out.

In order to deal with this problem, the batteries released to date have all air holes sealed as small as possible, and the holes are covered with tape until use, or the entire battery is placed inside a waterproof material. We are taking measures such as sealing it up. but,
When a battery is used, harmful gases enter and exit at the same time as oxygen gas flows in, and no fundamental solution has been reached. A more advanced method is to install a layer of water repellent such as a porous fluororesin membrane or moisture absorbent such as non-woven fabric between the air inlet hole of the battery and the air electrode to prevent leakage. Although this method has shown some degree of effectiveness, the permeation of harmful gases has not been prevented in this case as well.

The optimal mechanism for an air battery that completely blocks the permeation of liquid 2 and harmful gases and does not impede the permeation of the necessary amount of oxygen gas is considered to be the most suitable mechanism for an air cell that completely blocks the permeation of liquid 2 and harmful gases, but does not impede the permeation of the required amount of oxygen gas. This is the function of selectively permeating only oxygen gas, that is, the use of a so-called oxygen gas selective permeation membrane. Currently, examples of air batteries using such oxygen gas selective permeation R' include a method in which the membrane is brought into close contact with the 9-electrode and then incorporated into the battery circle, and a method in which the membrane is used to close the air hole T. is being tested. However, when the membrane is integrated with the air electrode, not only is the work complicated, but the membrane is likely to be damaged, and furthermore, if the membrane is not completely uniform, the air electrode may deteriorate locally. Such a situation may also occur. In addition, when using a membrane to block the air holes, the membrane area through which oxygen gas permeates becomes smaller, which reduces the amount of oxygen that comes into contact with the air electrode, making large current discharge difficult, and If the airtightness is broken through the gap between the outer can and the part where the outer can is closed or where it contacts the bottom plate, there is a drawback that the can will be completely defenseless.

[Purpose of the invention]

Misfire F! In view of the above points, oxygen gas selective permeation membrane, which is considered to be extremely necessary in terms of the structure of an air battery, is provided between the outer can and the air electrode via an air diffusion layer, so that the oxygen gas is supplied from the outside. The purpose of the present invention is to provide an air battery that utilizes the oxygen gas efficiently, enables high output, and has long-term use and storage stability.

[Summary of the invention]

The present invention provides an air battery in which oxygen gas supplied from an air inlet provided in an outer can is used as an active material to cause a chemical reaction on an air electrode, and an air diffusion layer is provided between the outer can and the air electrode. This is an air battery equipped with an oxygen gas selectively permeable membrane.

In other words, in the present invention, oxygen gas is first supplied from the outside to the air diffusion layer between the outer can and the oxygen gas selectively permeable membrane through the air inlet of the outer can, and then this oxygen is supplied throughout the oxygen gas selectively permeable membrane. After permeating, the oxygen gas reaches the air electrode via the air diffusion layer between the oxygen gas selectively permeable membrane and the air electrode. As a result, oxygen gas from the outside comes into contact with the entire surface of the air electrode uniformly and with high efficiency, making it possible to increase output and obtain an air pond that can be used for a long time and has good storage stability. .

In the present invention, the means for providing the oxygen gas selective permeation membrane between the outer can and the air electrode via the air diffusion layer is to attach a support and attach the oxygen gas selective permeation membrane to the support using an adhesive or the like. The means for fixing, the means for processing the outer can, the backing for sealing the battery, and the means for fixing the oxygen gas selectively permeable membrane can be selected as appropriate.

The performance required of the oxygen gas selectively permeable membrane used in the present invention is preferably as follows, based on a comparison of the membrane permeation rates of water vapor and oxygen gas, which are considered to be the most harmful to the battery. Oxygen gas permeation rate 10-”/+b, cd, cs
kIt or more or water vapor transmission rate 1g-"d/am-
・--The following must be 6, and the ratio of oxygen permeation rate to water vapor permeation rate must be 1.5 or more. More preferably, the above ratio is 3.0 or more. However, these conditions depend on the structure and size of the battery, the area of the air electrode, the type and amount of electrolyte, and the intended use of the battery (for large current discharge,
It is necessary to change it depending on the type of discharge (long-term discharge, continuous discharge, intermittent discharge, etc.).

Specifically, conventionally known fluororesins can be used, but for practical purposes, 8n02, ZnO, Allas% MgO, Cab obtained by a sputtering method or a vapor deposition method is used.

It is preferable to use a metal oxide thin film having water-containing or water-utilizing properties such as Bad, 5rO1Tie2.5i01, or a composite film of this thin film and FBP.

〔Effect of the invention〕

In the air battery of the present invention in which an oxygen gas selectively permeable membrane is fixed, a necessary amount of oxygen gas can pass through the membrane and reach the air electrode, and the amount of permeation and inflow of water vapor can be kept extremely low. Furthermore, it is possible to provide appropriate voids on both sides of the membrane that contribute to gas diffusion, allowing air to be removed due to unevenness on the surface of the membrane or air electrode, or differences in distance from the air inflow hole. The localization of the ultimate reaction point can be reduced, thereby increasing the reaction efficiency of oxygen on the air electrode,
It can enable large output discharge. In addition, compared to conventional methods, the work is easier than, for example, a method in which an oxygen gas permselective membrane is integrated with an air electrode and then incorporated into the battery, and the battery output is not affected by the unevenness of the anode or the surface of the air electrode. is decreasing. Furthermore, compared to the method of directly fixing the oxygen gas selective permeation membrane to the inside of the outer can, the effective area of the part of the membrane through which oxygen permeates becomes larger.
Large current discharge becomes possible.

[Embodiments of the invention]

Hereinafter, the invention will be explained based on an example using a cylindrical wave (LR44 type) zinc-air battery as an example.

<Examples 1 to 3> As shown in Fig. 1, the air electrode 1 and the separator 5 were installed in the gasket 6.4, which had a circular groove concentric with the 5-shaped groove for fixing the air electrode and the separator. A cylindrical oxygen gas selectively permeable membrane 14t is inserted into this portion and bonded. As an air electrode, a flat hole diameter of 1o
Gas-permeable water-repellent membrane layer consisting of a 100 μm thick polytetrafluoroethylene (PTFB) membrane with uniformly distributed micropores; 4% by weight platinum, 80% by weight activated carbon powder with an average particle size of 100 μm, PTFE powder After mixing 16 wt.
An air electrode with an integrated structure of five cods was used. In addition, a potassium hydroxide aqueous solution was used as the electrolyte, and zinc powder, which acts as a negative electrode active material, was dispersed together with a gelling agent to form negative electrode mixture 6, which was filled into the battery. A negative electrode current collector 7 made of a brass needle with a diameter of 21,111 mm was installed inside.The adhesive for attaching the gas selectively permeable membrane to the gasket was polysilicon, tyrene (Example 1), and a two-component mixture that hardens at room temperature. Type epoxy resin (Example 2) and polyamide (Example 3) were used.

After creating the zinc-air type a with the above structure, the upper and lower ends of the outer can were tightened to improve the adhesion between the gasket and the membrane.

<Examples 4 to 6> As shown in Figure 2, an oxygen gas selective permeation membrane was inserted between the gasket and the outer can, and polystyrene (Example 4) and room temperature curable two-component epoxy resin (Example 5) were used. , fc is wrapped around polyamide (Example 6) and glued, and then the outer can is made of
Zinc-air batteries were manufactured in the same manner as in Examples 1 to 3, except that the part of the gasket that was in contact with the PLC was recessed inward to create a gap between the membrane and the part of the outer can that had air inflow holes. It was created.

In addition to the above-mentioned examples, a zinc-air battery was fabricated as an example using the oxygen gas selective permeation M'fr method and the conventional method of incorporating an oxygen gas selective permeation membrane.

Comparative Example 1> A zinc-air battery was produced in the same manner as in Examples i to 3 except that the oxygen gas selectively permeable membrane was not used.

<Comparative Example 2> A zinc-air battery was produced in the same manner as in Comparative Example 1, except that an air electrode having a water-repellent film and an oxygen gas selectively permeable M pressure-bonded on the surface was used.

Comparative Example 3゛〉 A zinc-air battery was manufactured in the same manner as in Comparative Example 1, except that an oxygen gas selectively permeable membrane was directly adhered to the inner wall of the outer can using a 2g mixed epoxy resin that hardens at room temperature. did.

Zinc-air batteries made using the above nine methods each have 20 to 3
0 bottles were stored in an atmosphere of 45°C and 90% relative humidity,
The time until 50% of the battery of each structure leaked was measured. 25°C, 70% relative humidity.

The average output current of each battery during 2.50 discharges was measured, and the result t of fc0 or more was calculated from that value and shown in Table 1 along with the specific output energy amount.

Table 1 X1 (Example of the Invention) The present invention will be described below based on an example of a counterfeit cylindrical (LR44 type) zinc-air battery.

<Examples 7 to 9> As shown in FIG. 3, a square ring-shaped support 16 made of butyl rubber was installed in the outer can 10 provided with a nitrogen gas flow hole 10', and an oxygen gas selective permeation membrane 14 was bonded to this. It was attached using an adhesive.

Inside the oxygen gas selective permeation membrane, a gas-permeable water-repellent layer consisting of a polytetrafluoroethylene (PTFE) membrane with a thickness of 100 μm having uniformly distributed micropores with an average pore diameter of 10 μm; 80% by weight of activated carbon powder with an average particle size of 100 μm and 1 part of PTFB powder were rolled to a thickness of 0. 5 rim porous nocturnal catalyst layer; 0.1 mφ40 mm, cylindrical. An air electrode 1 was provided having a structure in which a three-layer current collector layer consisting of all nickel materials was integrated under a pressure of fl tOn/cdL. 1! Hydroxylated as a solution.

Using a potassium aqueous solution and zinc powder as a negative electrode active material,
Both were filled into the battery as a negative electrode mixture 6 by dispersing zinc powder in an electrolytic solution containing a gelling agent.

In this mixture, a negative electrode current collector 7"f. consisting of a needle with a diameter of 27' was installed. An oxygen gas selectively permeable membrane was placed on the support 1.
Polystyrene (Example 7), room-temperature curable two-component epoxy resin (Example 8), and polyamide (Example 9) were used as adhesives for attaching to No. 3.

<Example 10> As shown in Fig. 4, a zinc-air battery was produced in the same manner as in Example 7, except that the upper and lower ends of the side surface of the outer can were pressed into a band shape, and the inside of this hollow part was used as a support. Created.

<Examples 11 and 12> As shown in Fig. 5, the upper and lower ends of the sides of the outer can are each pressed into two strips, which can be inserted between the two hollow parts and into these parts from the inside of the can. The oxygen gas selectively permeable membrane was sandwiched between square rings of the same size, and the membrane was fixed without using an adhesive (Example 11) or with a polystyrene adhesive (Example 12). A zinc-air battery was produced in the same manner as in Example 7.

<Example 13> As shown in FIG. 6, a zinc-air battery was produced in the same manner as in Example 7, except that circular convex portions were provided on the gasket tube and 4 and integrated with the support body.

<Example 14> As shown in FIG. 7, a zinc-air battery similar to that of Example 13 was constructed in which the membrane adhesion portion was pressed from the outside using an O-ring 15.

<Example 15> As shown in Fig. 8, upper, middle, and lower C-square ring supports were installed outside the air electrode, and an oxygen gas selectively permeable membrane was pasted with polystyrene on the outside. A zinc-air battery was produced in the same manner as in Example 7, except that the upper and lower ends of the battery were sealed with polystyrene.

〈Example 16.17〉 As shown in Fig. 9, square ring-shaped supports were installed in double layers above and below the outside of the air electrode, and an oxygen-gas selective permeation membrane was placed between them without using an adhesive ( A zinc-air battery was produced in the same manner as in Example 7, except that it was fixed using Example 16) or polystyrene adhesive (Example 17).

<Example 18> As shown in Figure '10, a monooxygen gas selectively permeable membrane was
A zinc-air battery was produced in the same manner as in Example 7, except that the upper and lower end portions were attached to a wire mesh support provided on the outside of the pole.

<Example 19> A wire mesh support was immersed in a dilute toluene solution of polystyrene, then pulled up, excess solution gold was removed, an oxygen gas permeable membrane was layered and adhered, and this was placed outside the air electrode. A zinc-air battery was produced in the same manner as in Example 7, except that the structure was the same as in Example 18.

20 to 30 of each of the above 13 types of zinc-air batteries were heated at 45°C.
Five cells of each structure were stored in an atmosphere of 90% relative humidity.
The time until 0% leakage was measured.

In addition, the average output current for each cell was measured during 2.50 discharges at 25° C. and 70° relative humidity. As shown in this table above, the zinc-air battery having the structure of the present invention can extract the same amount of energy as the conventional zinc-air battery that does not take leakage resistance into consideration, and it also has leakage resistance. Much improved. Furthermore, it was able to extract a larger current while having leakage resistance equivalent to that of conventional leakage-resistant zinc-wall batteries.

From the above results, the present invention is considered to be extremely useful industrially.

In addition, is the structure basically equivalent to this example? A similar effect was observed when using square or button-shaped batteries with zinc-air batteries. Furthermore, similar effects could be obtained in an FC all-air battery using a metal other than zinc as the negative electrode active material, such as a FC battery made of iron ore.

[Brief explanation of drawings]

1 to 10 are cross-sectional views of the air battery according to the present invention. i,,,,air electrode 2,,,,lead 3.4.
,,,gas,') 5 ,,,,separator 6
,,,, negative electrode mixture 7 e+++ negative electrode current collector 8 ,
,,,Positive terminal 9 ,,,Negative terminal 10 ,,,
, Exterior can 1o': ,,, Sudden air inlet 11 , 12
,,,,Grono,) 13,,,,Support 14
,,,,Oxygen gas selective permeation membrane 15,,,,0-・
Ring Representative Patent Attorney Kensuke Norichika (and 1 other person) Fig. 1 Fig. 2 Fig. 47 Fig. 3 γ4 Fig. 4 Fig. 5 Fig. 6 q 4 7 Fig. 7 Fig. 8 q4.1 No. 9 Figure 10

Claims (1)

[Claims] α) Supplied from the air inlet provided in the outer can. An air battery that uses oxygen gas as an active material and causes an electrochemical reaction on an air electrode, characterized in that: 1. An oxygen gas selective permeation membrane is provided between the outer can and the air electrode via an air diffusion layer. A full charge battery.