JP2822485B2 - 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, reference numeral 1 denotes an oxygen electrode (air electrode), and 2 denotes a water-repellent film supporting an oxygen electrode made of polytetrafluoroethylene (PTFE) which has gas diffusibility but prevents a solution. Reference numeral 3 denotes a hole for taking in air from outside, 4 denotes a porous body for supporting an oxygen electrode and diffusing air, 5 and 6 denote separators, and 7 denotes a negative electrode composed of a mixture of an aqueous solution of potassium hydroxide and zinc aluminide. . Generally, an alkaline electrolyte uses an aqueous solution of potassium hydroxide at a concentration of 30 to 35%. For this reason, when the relative humidity is higher than 47 to 59%, external moisture is taken in, the concentration of the electrolyte decreases and the volume expands, and the discharge performance decreases and the electrolyte leaks. 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 non-woven fabric made of paper or a polymer material is provided to prevent leakage of the electrolyte to the outside of the electricity. Furthermore, 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 limited by making the air holes extremely small. And discharge performance, especially in long-term discharge. The main causes of these are the dilution and volume expansion of the electrolyte due to the penetration of water vapor into the battery, and the inhibition of the discharge reaction based on the generation of carbonate due to the penetration of carbon dioxide gas and the obstruction of the air flow path. On the other hand, when the outside air is low in humidity, the evaporation of water in the electrolytic solution causes 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 taking in the battery at a high speed and preventing water vapor and carbon dioxide gas in the atmosphere from entering the battery for a long time.

Means for Solving the Problems The present invention relates to a gas diffusion electrode using oxygen as an active material, and 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. In between, a polyorganophosphazene membrane is interposed as an oxygen-selective permeable membrane.

Further, a microporous film made of polyolefin such as polypropylene or polyethylene, a fluororesin, polysulfone or the like having excellent alkali resistance was selected as a support for this film, and the study was completed. The support may be a single layer, but in order to ensure strength during handling, production or use, it may have a composite film structure of two or more layers further integrated with an alkali-resistant nonwoven fabric as necessary. .

The present invention is a polyorganophosphazene film, as a result of intensive studies for batteries, as a whole, satisfying the above characteristics,
It was found that the performance of the battery to which this was applied was extremely excellent and completed.

Operation As is clear from the results of the battery test in the examples described later, this configuration must satisfy both the oxygen transmission rate for batteries and the effect of shutting off water vapor and carbon dioxide from the atmosphere. Accordingly, both the high load discharge performance required for a practical battery and the performance when discharged for a long time in an atmosphere of high humidity or low humidity are satisfied.

Example An example of the present invention will be described.

According to the method described by Allcock et al. (Inorg, Chem., 5 , 1709 (1966)), (diisoamyloxyphosphazene) was synthesized, cast from a tetrahydrofuran (THF) solution onto a glass plate, and then 100 μm in diameter. A battery using this membrane, a battery using polypropylene as a support of the phosphazene membrane, and a battery not using the above membrane as a comparative example were evaluated by trial production and examined.

In the case of the comparative example, the configuration was exactly the same as in FIG. The embodiment using a polyorganophosphazene film is almost the same as that shown in FIG. 2. As shown in FIG. 1, a polyorganophosphazene film is provided between a water-repellent film 2 made of PTFE and a porous material 4 for diffusing oxygen. The difference from the battery shown in FIG. 2 lies in that a phosphazene membrane and an alkali-resistant microporous membrane are used as a support for the phosphazene membrane.

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 or decrease before and after the discharge test, and is a numerical value mainly indicating uptake of moisture during discharge or some degree of evaporation.

The support of the composite membrane 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, in a high-load test at 20 ° C and normal humidity, the discharge period is short, and the influence of water uptake and evaporation and the influence of carbon dioxide gas are small. It is not necessary to consider so much the transmission blocking. 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 of Comparative Example were obtained, and it was confirmed that the speed of oxygen permeating the composite membrane sufficiently followed the speed 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 voltage of the battery in the comparative example, which does not have a mechanism to prevent the permeation of moisture or carbon dioxide, is depleted of water, or conversely, the air hole is blocked due to leakage due to the excessive intake of moisture, and the voltage drops during discharge, resulting in high load. Only a capacity corresponding to a part of the discharge capacity obtained in the 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.

Taken together, the prototype battery using the polyorganophosphazene composite membrane on the support of the microporous membrane has excellent high load characteristics and low load characteristics, good change in the external atmosphere, and especially alkali resistance. It can be concluded that an excellent battery can be provided when the microporous membrane is used as a support. Further, the same effect can be obtained with the microporous membrane supporting the polyorganophosphazene membrane shown in the examples even with other microporous membranes having alkalinity (for example, nylon microporous membrane). Further, in Example 2, a case was described in which the support was a composite layer formed by integrating a microporous membrane and a nonwoven fabric made of polypropylene.
Similar effects can be obtained if the nonwoven fabric is another alkaline material such as polyethylene or nylon.

In the examples, it was confirmed that substantially the same result was obtained even when the oxygen-selective membrane side 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. 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 Examples. Thus, 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 cross-sectional view of a button-type zinc-air battery used for studying the examples and comparative examples of the present invention, and FIG. 2 is a cross-sectional view of a conventional button-type zinc-air battery not using 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.

──────────────────────────────────────────────────の Continuing on the front page (51) Int.Cl. ⁶ Identification symbol FI H01M 12/06 H01M 12/06 F (72) Inventor Nobuyuki Yanagihara 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. 56) References JP-A-1-38564 (JP, A) JP-A-1-38551 (JP, A) JP-A-1-246811 (JP, A) JP-A-63-121023 (JP, A) JP-A-63-256118 (JP, A) JP-A-56-57828 (JP, A) (58) Fields investigated (Int. Cl. ⁶ , DB name) H01M 2/16 H01M 12/06 H01M 4/06 H01M 6 / 02 H01M 2/02

Claims (2)

(57) [Claims] 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 polyorganoorganizer is provided between an air intake side of the gas diffusion electrode and an inner surface of the battery container. A battery comprising a phosphazene film and an alkali-resistant microporous film that supports the polyorganophosphazene film. 2. An alkali-resistant microporous membrane comprising a polyolefin,
2. The battery according to claim 1, wherein the main component is one of a fluororesin and polysulfone.