JPH0475253A - Manufacture of battery - Google Patents

Abstract

PURPOSE:To improve the storage properties and long-range service performance of a battery by forming on a microporous film having predetermined microholes a predetermined thin film by sputtering method using La1-XSrXCo1-YFeYO3-Z (0<=X<1, 0<=Y<1, 0<=Z<1) as a target. CONSTITUTION:A thin film of thickness 2000Angstrom is formed using sputtering method which uses a mixed gas of Ar and N2 (the partial pressure ratio of Ar to N2: N2/Ar=25%) and by the use of La0.2Sr0.8Co0.8Fe0.2O2.7 as a target on one side of a polycarbonate film 4 of thickness 6mum having microholes of average diameter 0.05mum therethrough, so as to obtain a composite film 11. Such a battery is excellent at both heavy and light load characteristics and an excellent battery which is stable against changes in ambient atmosphere can be offered.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a gas diffusion electrode using oxygen as an active material, an electrolytic solution consisting of an alkaline aqueous solution, and a metal such as zinc, magnesium, or aluminum, or alcohol, hydrazine, or hydrogen. The present invention relates to a method for manufacturing a battery including negative electrode active materials such as the above.

BACKGROUND OF THE INVENTION BACKGROUND ART Batteries equipped with gas diffusion electrodes and using oxygen as an active material include air cells, fuel cells, and the like. Especially alkaline aqueous solution,
In batteries that use a neutral salt aqueous solution as the electrolyte,
Water vapor flows in and out from the gas diffusion electrode (oxygen electrode) depending on the internal vapor pressure, causing changes in the concentration and volume of the electrolyte in the battery, which affected the battery's performance characteristics. Taking a button-type air battery as an example, the situation will be explained using FIG. In the figure, 1 is an oxygen electrode (air electrode), and 2 is a porous water-repellent membrane that supports the oxygen electrode 1 and is made of polytetrafluoroethylene (PTFE), which has gas diffusivity but blocks liquid. 3 is an air intake hole from the outside, 4 is a porous body for air diffusion, 5.6 is a separator, 7 is a negative electrode zinc, and the alkaline electrolyte impregnated and retained in these is a potassium hydroxide aqueous solution, Its concentration is 30-35% by weight. For this reason, when the relative humidity is higher than 47 to 59%, external moisture is taken in, resulting in a decrease in electrolyte concentration and volumetric expansion, resulting in a decrease in discharge performance and leakage of the electrolyte. On the other hand, when the relative humidity is below the above range, evaporation of the electrolytic solution occurs, resulting in an increase in internal resistance and a decrease in discharge performance. Therefore, it is easily affected by the environmental atmosphere, so
Problems arose in battery characteristics after long-term storage, which restricted the use of air cells and fuel cells in specific fields and posed a major challenge in making them more versatile. In addition, in the figure, 8 is a negative electrode container containing negative electrode zinc 7, 9 is an insulating gasket, 1
0 is a positive electrode container.

Problems to be Solved by the Invention Various proposals have been made in the past in order to improve these problems. For example, a substance that reacts with the electrolyte is inserted into a portion around the air hole to prevent the electrolyte from leaking to the outside of the battery. Alternatively, an electrolyte absorbing material such as a nonwoven fabric made of paper or a polymeric material is provided to prevent leakage of the electrolyte to the outside of the battery. Furthermore, proposals have been made to prevent water vapor and carbon dioxide from entering the battery by making the air holes extremely small (even by limiting the amount of oxygen supplied).

However, both methods had major problems in preventing liquid leakage and discharge performance, especially in long-term discharge performance. The main causes of these are the dilution and volumetric expansion of the alkaline electrolyte due to the entry of water vapor from the air into the battery, and the inhibition of the discharge reaction due to the formation of carbonates due to the entry of carbon dioxide gas, and the blockage of the air circulation path. However, when the outside air has low humidity, the loss of moisture in the electrolyte causes performance to deteriorate. In order to eliminate this cause, in recent years, methods have been developed to control the amount of permeation of water vapor and carbon dioxide gas and to supply air to the oxygen electrode through a membrane that selectively allows oxygen to permeate with priority. A method has been proposed that uses a film in which a uniformly porous thin film, a thin film of a metal oxide, or an organic compound containing a metal element is integrated with a suitable porous film.

However, to date, it has not been possible to achieve a sufficiently effective oxygen permselectivity, so satisfactory discharge performance cannot be obtained, and the battery cannot withstand long-term use or storage, so it has not been put into practical use. not present.

Therefore, the present invention aims to improve the storability and long-term use performance of the above-mentioned battery, and to selectively remove oxygen from the atmosphere in order to obtain satisfactory discharge performance under a wide range of discharge conditions from light loads to heavy loads. The purpose of this invention is to provide an effective means for introducing water vapor into the battery at a sufficient rate and preventing the entry and exit of water vapor into the battery and the entry of carbon dioxide gas from the atmosphere into the battery over a long period of time.

Means for Solving the Problems In order to achieve the above objects, the present invention provides an air intake system for a gas diffusion electrode of a battery comprising a gas diffusion electrode using oxygen as an active material and a battery container having an air intake hole communicating with outside air. Ar and N2 are used as sputtering gas between the side and the inner surface of the battery container.
La1-xS r
A composite film obtained by forming a thin film on a microporous substrate using zco+-yFeyoz as a target was interposed.

The present invention forms a thin film on a microporous substrate using La+-xS rxCo+-yFeyoz as a target by a sputtering method using a mixed gas of Ar and N2 as a sputtering gas as a film with excellent oxygen selective permeability. We focused on the high oxygen selective permeability of the composite membrane obtained by this method.

This membrane has the oxygen permeation rate necessary to obtain satisfactory discharge performance under heavy loads, and the permeation prevention of water vapor and carbon dioxide gas to withstand long-term storage and long-term discharge under low humidity or high humidity atmospheres. They found that the performance of batteries to which this membrane was applied was extremely excellent, and they completed it.

Function: As is clear from the results of the battery test in the Examples described later, the composite membrane with this configuration has a good oxygen permeation rate for batteries and blocks water vapor and carbon dioxide from entering the battery. Both the heavy load discharge performance required of a practical battery and the performance when discharged for a long time in an atmosphere of high humidity or low humidity can be maintained in a satisfactory state.

Example (Example 1) L
ao, 2s ro, ec oo, aF eo, ro2.
7 as a target, a mixed gas of Ar and N2 (Ar
A thin film having a thickness of 2000 A was formed by a sputtering method using a partial pressure ratio of N2 and N2 (N2/Ar=25%) to form a composite film.

(Example 2) Ar and N were applied to one side of a polycarbonate film with the same specifications as that used in Example 1 using LaCoO3 as a target.
2 mixed gas (partial pressure ratio of Ar and N2: N2/Ar=25
A thin film with a thickness of 2000 Å was formed by a sputtering method using %) to form a composite film.

(Comparative Example 1) La
o, 2s ro, sc oo, sF eo, 202.7
A thin film having a thickness of 2000 A was formed by a sputtering method using a mixed gas of Ar and N2 (partial pressure ratio of Ar and N2: N2/Ar=25%) using the target as a composite film.

(Comparative Example 2) Lao, zs ro, sCoo, eF eo were coated on one side of a polycarbonate membrane with the same specifications as that used in Example 1.
, 202.7 as a target, a thin film with a thickness of 2000A was formed by sputtering using only Ar,
Composite, membrane.

(Comparative Example 3) La
o, 2s ro, ec oo, eF ea, 202. −
A mixed gas of Ar and N2 (Ar
A thin film having a thickness of 400 A was formed by a sputtering method using a partial pressure ratio of N2 and N2 (N2/Ar = 25%) to form a composite film.

(Comparative Example 4) Lag
, 2s ro, aCoo, eFeo, 2027 as a target, 1 was sputtered using a mixed gas of Ar and N2 (partial pressure ratio of Ar and N2: Np/Ar = 60%).
A thin film having a thickness of 00OA was formed to form a composite film.

(Comparative example 5) A porous water-repellent membrane is used, but a composite membrane is not used.

In order to confirm the effects of the present invention, a battery using the composite membranes prepared in Examples 1 and 2 and the composite membranes of Comparative Examples 1 to 4, and a battery not using the composite membrane were prototyped and evaluated. investigated. First, in the case of Comparative Example 5 in which no composite membrane was used, the configuration was exactly the same as that in FIG. 2. Next, as shown in Fig. 1, a battery using a composite membrane has a structure in which each composite membrane is interposed between a porous PTFE membrane 2 and a porous body 4 that disperses and equalizes the flow of oxygen. That is.

The dimensions of the prototype batteries are 11.6 m in diameter and 5 m in total height.
．． 4+m, and the sufficiency of the rate of oxygen uptake into the battery was evaluated by continuous discharge at 20°C and normal humidity (60% RH) under a relatively heavy load (75Ω).
Long-term continuous discharge at 20°C, high humidity (90% RH), and low humidity (20% RH) at a temperature of 3 Ω) prevents the intake of water vapor from the atmosphere into the battery during the long-term discharge period. We evaluated the effects on battery performance, such as evaporation of water inside the battery and uptake of carbon dioxide gas.

The details of the prototype battery are shown in Table 1. Here, as is clear from comparing Comparative Examples 1 to 4 and Examples 1 and 2, the gas permeation rate ratio of oxygen and water vapor is less than 1 in all of the comparative examples, and oxygen It cannot be said to be a selectively permeable membrane. However, in all the examples, the value was 3 or more, indicating that the composite membrane of the present invention has excellent oxygen selective permeability for use in batteries.

Table 2 also shows the performance test results of the prototype batteries.

(Left below) In Table 2, the end-of-discharge voltage is 9V in all cases, and the change in weight indicates an increase or decrease before and after the discharge test, which mainly suggests the amount of water taken in or evaporated during discharge. This is the numerical value.

The present invention can be most clearly explained in detail by comparing the characteristics of these batteries with Comparative Example 5, which does not use a composite membrane.

First, in a heavy load test at 20℃ and normal humidity, the discharge time was short.
Since the influence of moisture uptake and evaporation and the influence of carbon dioxide gas are small, there is no need to consider blocking the permeation of moisture and carbon dioxide gas as long as the oxygen supply rate is sufficient for battery performance. Therefore, under such conditions, excellent characteristics can be obtained even in Comparative Examples 1 to 5. On the other hand, in Examples 1 and 2 described above, discharge characteristics equivalent to Comparative Examples 1 to 5 were obtained, and the rate at which oxygen permeates through the composite membrane sufficiently follows the rate at which oxygen is consumed in the discharge reaction. It shows that

On the other hand, in the case of light load discharge, the discharge time is long, and in addition, when the outside air is high or low humidity, it is necessary to obtain battery characteristics that are superior in preventing the permeation of moisture and carbon dioxide gas, especially moisture, rather than the oxygen supply rate. The batteries of Comparative Examples 1 to 5, which do not have a sufficient mechanism to prevent the permeation of moisture and carbon dioxide gas, suffer from discharge due to depletion of moisture or, conversely, blockage of air holes due to leakage due to excessive intake of moisture. The voltage drops along the way,
A capacity equivalent to only a portion of the discharge capacity obtained in the heavy load test is obtained. Furthermore, it goes without saying that liquid leakage during discharge is a fatal problem in practical terms. On the other hand, the Examples showed extremely excellent performance, and a capacity almost equal to the discharge capacity in the heavy load test was obtained. These trends are the same whether the test atmosphere is high humidity or low humidity. This shows that in the case of the example, the moisture permeation blocking effect of the composite membrane was sufficiently exhibited.

Taking all the above into account, La1-Xs rxCo
A battery using a composite film obtained by forming a thin film on a microporous substrate using +-yFeyoz as a target has heavy load characteristics.

It can be concluded that it is possible to provide an excellent battery that has excellent light load characteristics and is stable even under changes in the external atmosphere.

In addition, in the above embodiment, the composite membrane of the present invention was installed between the battery container and the porous body for air diffusion, but if the mechanical strength of the composite membrane of the present invention is sufficient, the air diffusion There is no difference in battery characteristics even if the porous material is removed. Furthermore, in the above example, the composite membrane of the present invention was installed between the oxygen electrode and the porous membrane supporting the oxygen electrode, but if the oxygen electrode has sufficient strength, the supporting porous membrane is unnecessary. Even in that case, the battery characteristics will not change. We also confirmed that air batteries using neutral salt aqueous solutions such as ammonium chloride and zinc chloride as electrolytes have the same effect as batteries using alkaline electrolytes shown in the examples. There is.

Effects of the Invention As is clear from the above explanation, the oxygen selectively permeable composite membrane of the present invention can be used in a wide range of practical applications, from heavy loads to light loads, in batteries using neutral or alkaline aqueous solutions as electrolytes. It has the effect of being able to obtain high performance, excellent leakage resistance, and long-term storage.

[Brief explanation of drawings]

FIG. 1 is a cross-sectional view of a button-type zinc-air battery used to study examples and comparative examples of the present invention, and FIG. 2 is a cross-sectional view of a conventional button-type zinc-air battery that does not use a composite membrane. 1... Oxygen electrode (air electrode), 2... Water repellent membrane, 3... Air intake hole, 4... Porous membrane, 5, 6... ... Separator, 7 ... Negative electrode zinc, 8 ... Negative electrode container, 9 ... Insulating gasket, 10 ... Positive electrode container, 11 ...・・・
...Composite membrane. Name of agent Patent attorney Shigetaka Awano et al. 12 No. 2 Figure f-・-*1 11-・11] Written amendment June 1991 ■ Indication of the case 2 Name of the invention Method of manufacturing batteries 6 , Contents of amendment (1) [La 1-JXSrz on page 6, line 5 of the specification]
CO1 IFga O2J [La1-5(SrzCol-Y
Correct to I'elY 03-ZJ. (2) [La14SrzCo1-Y on page 6, line 11]
Fey OzJ F La1-zsrz Col yF
6y Correct to Okawa J. (3) “Table 2” on page 13 of the same document will be amended as shown in the attached sheet. (4) r La 14Srz C on page 15, line 18
0I-J/ FeYOz J [L1 cap 5rzCo+-
Correct to yFeyos-z J. Target of representative 6 amendment

Claims (4)

[Claims] (1) A gas diffusion electrode containing oxygen as an active material and a battery container having an air intake hole communicating with the outside air are provided, and between the air intake side of the gas diffusion electrode and the inner surface of the battery container, La_1_-_XSr_XCo_1_-_YFe_YO is provided.
＿３＿－＿Z(However, 0≦X<1, 0≦Y<1, 0≦Z<
Oxygen selective permeation obtained by using 1) as a target and forming a thin film by sputtering using a mixed gas of Ar gas and nitrogen gas on a microporous film having micropores of 0.1 μm or less. A method for manufacturing a battery using a composite membrane. (2) The method for manufacturing a battery according to claim 1, wherein the thin film has a thickness of 500 to 2000 Å. (3) The method for manufacturing a battery according to claim 1, wherein the nitrogen partial pressure ratio in the mixed gas is 0.1 to 50%. (4) The method for manufacturing a battery according to claim 1 or 2, wherein the oxygen selectively permeable composite membrane is in direct contact with the inner surface of the battery container having an air intake hole and the gas diffusion electrode.