JP2817343B2 - Battery - Google Patents

Description

The present invention relates to a gas diffusion electrode using oxygen as an active material, an electrolyte such as an alkaline aqueous solution, a metal such as zinc, magnesium, and aluminum, or an alcohol, hydrazine, or the like.
The present invention relates to a battery including a negative electrode active material such as hydrogen.

2. Description of the Related Art Examples of a battery including a gas diffusion electrode and using oxygen as an active material include an air battery and a fuel cell. In particular, in a battery using an alkaline aqueous solution or a neutral aqueous solution as an electrolyte, steam flows in and out of the gas diffusion electrode (oxygen electrode) according to the internal vapor pressure, and the concentration and volume of the electrolyte in the battery change, This affected battery characteristics. The situation will be described with reference to FIG. 2 taking a button-type zinc-air battery as an example. In the figure, 1 is an oxygen electrode (air electrode), and 2 is a porous membrane supporting an oxygen electrode made of polytetrafluoroethylene (PTFE) which has gas diffusibility but blocks liquid. 3
Is a hole for taking in air from outside, 4 is a porous body for supporting an oxygen electrode and diffusing air, 5 and 6 are separators, and 7 is a negative electrode composed of a mixture of an aqueous potassium hydroxide solution and zinc calomel powder. Generally, an aqueous solution of potassium hydroxide is used as the alkaline electrolyte, and its concentration is 30 to 35%. For this reason, when the relative humidity is higher than 47 to 59%, external moisture is taken in, and the concentration of the electrolyte and the volume expansion occur, resulting in a decrease in discharge performance and leakage of the electrolyte. On the other hand, when the relative humidity is lower than the above range, the electrolytic solution evaporates, resulting in an increase in internal resistance and a decrease in discharge performance.

Therefore, there is a problem in the characteristics after long-term storage because they are easily affected by the environmental atmosphere, and air cells and fuel cells are designed only for a specific field, and there is a major problem in achieving versatility. Was. In the figure, 8 is a negative electrode container, 9 is an insulating gasket, and 10 is a positive electrode container.

Problems to be Solved by the Invention In order to improve these problems, various measures have conventionally been studied. For example, a substance that reacts with the electrolyte is inserted into a portion around the air hole to prevent the electrolyte from leaking out of the battery. Alternatively, an electrolyte absorbing material such as a nonwoven fabric made of paper or a polymer material is provided to prevent the electrolyte from leaking out of the battery. Further, there have been proposals to prevent water vapor or carbon dioxide gas from entering the inside of the battery, even if the supply of oxygen is restricted by making the air holes extremely small. And discharge performance, especially in long-term discharge. These major causes are due to the dilution and volume expansion of the electrolyte due to the intrusion of water vapor in the air into the battery, and the inhibition of the discharge reaction based on the generation of carbonate due to the intrusion of carbon dioxide gas and the obstruction of the air flow path, On the other hand, when the outside air was low in humidity, the evaporation of water in the electrolytic solution caused a decrease in performance. To eliminate this cause, in recent years,
A method of controlling the permeation of water vapor or carbon dioxide gas and supplying air to the oxygen electrode through a membrane that selectively permeates oxygen preferentially,
For example, there has been proposed a method of using a polysiloxane-based nonporous uniform thin film or a film obtained by integrating a thin film of a metal oxide or an organic compound containing a metal atom with an appropriate porous film.

However, to date, satisfactory discharge performance has not been obtained due to insufficient effective oxygen gas selective permeability and insufficient permeation of water vapor and carbon dioxide gas. Since it had a technical problem that it could not withstand storage, it had not been put to practical use.

Accordingly, the present invention selectively improves the storability and long-term performance of the above-described battery and selectively suffices oxygen gas in the atmosphere in order to obtain satisfactory discharge performance under discharge conditions from low load to high load. It is an object of the present invention to provide an effective means for preventing the invasion of atmospheric water vapor and carbon dioxide gas into the electromagnetic field for a long period of time by taking it into the battery at a high speed.

Means for Solving the Problems The present invention provides a gas diffusion electrode using oxygen as an active material, an air intake side of a gas diffusion electrode of a battery including a battery container having an air intake hole communicating with the outside air, and an inner surface of the battery container. Between them, a cobalt porphyrin complex film or a mixed film of a cobalt porphyrin complex and polytrimethylsilylpropyne is interposed as an oxygen-selective permeable film.

Furthermore, as a porous base material for supporting the membrane, polypropylene, polyethylene, etc. having excellent alkali resistance were selected from polyolefin, fluororesin, polysulfone, etc., and the study was completed. The microporous membrane may be a single layer,
In order to ensure the strength during handling, production, or use, a two-layer or more structure in which an alkali-resistant nonwoven fabric is further integrated as necessary may be used.

The present invention has been completed, as a result of earnestly studying the above-described cobalt porphyrin complex film and the like for a battery, to comprehensively satisfy the above-described various properties, and to find that the performance of a battery to which the same is applied is extremely excellent. .

Operation As is clear from the results of the battery test in the examples described later with this configuration, simultaneously with the oxygen permeation rate for the battery, the effect of shutting off water vapor and carbon dioxide from the atmosphere is in a state to be satisfied. Both the high-load discharge performance required for a typical battery and the performance when discharged for a long time in an atmosphere of high humidity or low humidity are satisfied.

Example Hereinafter, an example of the present invention will be described.

Prototype of a battery using a cobalt porphyrin complex membrane as an oxygen-selective permeable membrane, a battery using a mixed membrane of a cobalt porphyrin complex membrane and polytrimethylsilylpropine as an oxygen-selective permeable membrane, and a battery not using the above membrane as a comparative example It was evaluated and examined.

In the case of the comparative example, the configuration was exactly the same as in FIG. The batteries using the cobalt porphyrin complex membrane as an oxygen-selective permeable membrane and the battery further using a mixed membrane of a cobalt porphyrin complex and polytrimethylsilylpropyne as the oxygen-selective permeable membrane. Is almost the same as in FIG. 2, and as shown in FIG.
The composite membrane of each embodiment is interposed between the porous membrane 2 and the porous body 4 that diffuses oxygen, and the composite membrane is arranged such that the side containing the complex faces the side of the air intake height 3. ,
It is different only from FIG.

The shape of the prototype battery is 11.6 mm in diameter and 5.4 mm in total height.
The sufficiency of oxygen uptake rate in the battery was evaluated by continuous discharge at 20 ° C and normal humidity (60% RH) at relatively high load (75Ω). Long-term continuous discharge at ℃, high humidity (90% RH) and low humidity (20% RH), captures water vapor in the atmosphere, evaporates water in the battery, and removes carbon dioxide gas during the long-term discharge period. The degree of influence on battery performance, such as loading, was evaluated.

The breakdown of the prototype battery is shown in Table 1. Table 2 shows the performance test results of the prototype battery.

In Table 2, the end-of-discharge voltage was 0.9V,
The change in weight indicates an increase and decrease before and after the discharge test, and is a numerical value mainly indicating uptake of water during discharge or some degree of evaporation.

The support of the composite membrane of the present invention is made of an alkali-resistant material. The effects of the present invention can be most clearly explained by comparing the characteristics of these batteries with those of a comparative example using no composite membrane.

First, the discharge period is short in the high load test at 20 ° C and normal humidity.
Since the influence of moisture uptake and evaporation and the influence of carbon dioxide gas are small, it is not necessary to consider the performance of the battery so much as to prevent the permeation of moisture and carbon dioxide gas if the supply rate of oxygen is sufficient. Therefore, under such conditions, excellent characteristics can be obtained even in the comparative example. On the other hand, in Examples 1 and 2 described above, the same discharge characteristics as those in Comparative Example were obtained, and it was confirmed that the velocity of oxygen permeating the composite membrane sufficiently followed the velocity of oxygen consumed by the discharge reaction. Is shown.

On the other hand, in the case of low load discharge, the discharge period is long, and in the case where the outside air is at high humidity or low humidity, the water and carbon dioxide gas, especially the prevention of permeation of water, are superior to the supply rate of oxygen. It becomes important. The battery of the comparative example, which does not have a moisture or carbon dioxide gas permeation prevention mechanism, has a low voltage in the middle of discharge due to depletion of moisture or congestion of air holes due to leakage of liquid due to excessive intake of moisture. Only a capacity corresponding to a part of the discharge capacity obtained in the load test is obtained. Needless to say, liquid leakage during discharge is a fatal problem in practical use. On the other hand, all the examples show extremely excellent performances, and these have obtained capacities almost equal to the discharge capacity in the high load test. These tendencies are the same whether the test atmosphere is high humidity or low humidity. This indicates that, in the case of the example, the effect of preventing moisture permeation of the composite membrane is sufficiently exhibited.

By integrating the above, a composite membrane with a cobalt porphyrin complex membrane formed on the surface of a microporous membrane and a prototype battery using a mixed membrane of a cobalt porphyrin complex and polytrimethylsilylpropyne have high load characteristics and low load characteristics. Both are excellent, and the change of the external atmosphere is also good. In particular, it is concluded that an excellent battery can be provided when an alkali-resistant microporous membrane is used for the support. Further, the same effect can be obtained by using a microporous membrane having another alkalinity, such as a nylon microporous membrane, as the microporous membrane supporting the composite membrane shown in the examples. Further, in the embodiment, the case where the support is a composite layer formed by integrating a microporous membrane and a nonwoven fabric made of polypropylene has been described, but the same applies if the nonwoven fabric is another alkali-resistant material such as polyethylene or nylon. The effect is obtained.

In each of the examples, it was confirmed that almost the same result was obtained even when the thin film side of the composite membrane was brought into contact with the air intake hole side.

Further, in the above-described example, the composite membrane of the present invention was installed between the battery container and the porous body for air diffusion, but the composite membrane of the present invention was a microporous membrane, and in some cases, a nonwoven fabric was further integrated. It is composed of a support, and there is no difference in battery characteristics even when the porous body for air diffusion is removed. However, when the strength of the composite membrane is not sufficient and the composite membrane is deformed toward the air intake hole, the porous membrane is provided to maintain the composite membrane in a stable shape. Further, in the above embodiment, the composite membrane of the present invention was installed via a porous membrane supporting the oxygen electrode between the oxygen electrode, but if the strength of the oxygen electrode is sufficient, the porous membrane is unnecessary and is excluded. However, the battery characteristics do not change. It was also confirmed that an air battery using an aqueous solution of a neutral salt such as ammonium chloride or zinc chloride as an electrolyte had the same effect as the battery using an alkaline electrolyte shown in the examples. The operation of the present invention can be explained for the same reason as in the embodiment.

Effects of the Invention As is apparent from the above description, according to the oxygen gas diffusion electrode of the present invention, excellent practical performance from high load to low load of a battery using a neutral or alkaline aqueous solution as an electrolyte, and excellent The effect of being able to provide liquid leakage resistance and long-term storage properties is obtained.

[Brief description of the drawings]

FIG. 1 is a half sectional view of a button-type zinc-air battery used in the study of the examples and comparative examples of the present invention, and FIG. 2 is a half sectional view of a conventional button-type zinc-air battery not using a composite membrane. is there. 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.

────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Nobuyuki Yanagihara 1006 Kazuma Kadoma, Kadoma-shi, Osaka Matsushita Electric Industrial Co., Ltd. (56) References JP 1-2677973 (JP, A) JP 1- 267974 (JP, A) JP-A-59-221971 (JP, A) JP-A-59-75582 (JP, A) JP-A-57-105969 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01M 12/06 H01M 4/86 H01M 2/16

Claims (2)

(57) [Claims] 1. A cobalt porphyrin complex comprising: a gas diffusion electrode using oxygen as an active material; and a battery container having an air intake hole communicating with the outside air, wherein a cobalt porphyrin complex is provided between an air intake side of the gas diffusion electrode and an inner surface of the battery container. A battery provided with a membrane. And a battery container having a gas diffusion electrode using oxygen as an active material and an air intake hole communicating with the outside air. A cobalt porphyrin complex is provided between an air intake side of the gas diffusion electrode and an inner surface of the battery container. And a mixed film of polytrimethylsilylpropyne and polytrimethylsilylpropyne.