Humidity-variation power-generation element

Abstract

To provide a humidity-variation power-generation element having high operational stability with respect to environmental conditions.SOLUTION: The present invention relates to a humidity-variation power-generation element that obtains an electromotive force by using humidity fluctuations in the environment. In both sides of an ion-permeable membrane, an aqueous electrolyte containing an ionic compound having deliquescence is accommodated together with an electrode. On one side of the ion-permeable membrane, the aqueous electrolyte is accommodated in the ion-permeable membrane under a waterproof moisture-permeable film that allows water vapor to pass. On the other side of the ion-permeable membrane, the aqueous electrolyte is accommodated in the ion-permeable membrane under a waterproof and moisture-proof film or wall that blocks at least moisture in the environment. The waterproof moisture-permeable film has flexibility and is provided along the surface of the aqueous electrolyte.SELECTED DRAWING: Figure 2

Description

[Technical Field]

[0001] The present invention relates to a humidity fluctuation power generation element that generates electricity using humidity fluctuations in the environment. [Background technology]

[0002] Humidity-fluctuation power generation elements such as humidity-fluctuation batteries can generate electricity on-site by utilizing humidity fluctuations in the environment, eliminating the need for wiring for power transmission. This means that they are expected to operate maintenance-free for long periods of time, for example, as a power source for small sensors for IoT. However, a tendency for the output voltage from humidity-fluctuation power generation elements to decrease over time has been observed.

[0003] For example, Patent Document 1 discloses a humidity-fluctuating battery having a structure in which an aqueous electrolyte solution containing a water-soluble polymer, which is an aqueous solution of a deliquescent ionic compound, is provided on both sides of an ion-permeable membrane made of a fluorine-based resin together with electrodes, and one first side is open to the environment, while the other second side is isolated from the environment by the ion-permeable membrane. Here, the aqueous electrolyte solution containing the water-soluble polymer is said to suppress water permeation through the ion-permeable membrane and reduce the decrease in output voltage over time. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Publication No. 2023-45541 Summary of the Invention [Problem to be solved by the invention]

[0005] As described above, in order to operate the humidity fluctuation power generation element without maintenance for a long period of time, it is necessary for the element to have high stability against the environment.

[0006] The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a humidity fluctuation power generation element that has high operational stability against environmental changes. [Means for solving the problem]

[0007] The present invention provides a humidity-fluctuation power generation element that generates electromotive force by utilizing humidity fluctuations in the environment, An aqueous electrolyte solution consisting of an aqueous solution of a deliquescent ionic compound is accommodated together with an electrode on each side of the ion-permeable membrane, and the aqueous electrolyte solution is accommodated on one side of the ion-permeable membrane by a waterproof / moisture-permeable membrane that allows water vapor to pass through, and the aqueous electrolyte solution is accommodated on the other side of the ion-permeable membrane by a waterproof / moisture-proof membrane / wall that blocks at least the moisture in the environment, and the waterproof / moisture-permeable membrane is flexible and is provided along the surface of the aqueous electrolyte solution.

[0008] According to this feature, the waterproof / moisture-permeable membrane can have an increased moisture absorption and release rate while also having an increased operational stability, thereby further improving operational stability against environmental changes.

[0009] In the above-described invention, the open end of the housing, which is a bottomed tubular body made of the waterproof and moisture-proof membrane / wall, may be closed with the waterproof and moisture-permeable membrane, the bottom side of the formed internal space and the open end side are separated by the ion-permeable membrane, the bottom side is filled with the aqueous electrolyte, and the open end side also contains the aqueous electrolyte. This feature makes it possible to increase the moisture absorption and release rate of the waterproof and moisture-permeable membrane while improving its operational stability, and also to improve its operational stability against environmental changes.

[0010] In the above-described invention, the waterproof / moisture-permeable membrane may be made of a porous fluororesin. Furthermore, the waterproof / moisture-permeable membrane may be provided with a coating on the side that comes into contact with the aqueous electrolyte, which enhances wettability with the aqueous electrolyte. The aqueous electrolyte may also contain a surfactant that enhances wettability with the waterproof / moisture-permeable membrane. These features can increase the moisture absorption and release rate of the waterproof / moisture-permeable membrane while also enhancing its operational stability, thereby further enhancing its operational stability against environmental changes.

[0011] In the above-described invention, the electrodes may be made of silver / silver chloride, and the aqueous electrolyte may be a chloride aqueous solution. Furthermore, the electrodes may be multi-layered, consisting of a silver / silver chloride layer and a layer of silver / silver chloride mixed with a resin. The waterproof / breathable membrane may be provided with a coating that reduces the transmission of ultraviolet light. The aqueous electrolyte may contain a desensitizer that inhibits the decomposition of silver chloride. The desensitizer may be phenosafranin. These features can inhibit electrode degradation and improve operational stability, thereby further enhancing operational stability against environmental changes. [Brief explanation of the drawings]

[0012] [Figure 1] 1 is a cross-sectional view of a humidity fluctuation battery (humidity fluctuation power generation element) according to the present invention. [Figure 2] FIG. 10 is a cross-sectional view of a humidity fluctuation battery in which a waterproof and breathable membrane is deflected. [Figure 3] 1 is a diagram illustrating the principle of ion permeation through a solid ceramic electrolyte. [Figure 4] FIG. 2 is an exploded perspective view of the humidity fluctuating battery. [Figure 5A] 3A to 3C are cross-sectional views showing the manufacturing process of the humidity fluctuating battery. [Figure 5B] 3A to 3C are cross-sectional views showing the manufacturing process of the humidity fluctuating battery. [Figure 5C] 3A to 3C are cross-sectional views showing the manufacturing process of the humidity fluctuating battery. [Figure 5D]3A to 3C are cross-sectional views showing the manufacturing process of the humidity fluctuating battery. [Figure 5E] 3A to 3C are cross-sectional views showing the manufacturing process of the humidity fluctuating battery. [Figure 6] FIG. 1 is a cross-sectional view showing a method of imparting deflection to a waterproof / breathable membrane. [Figure 7] 1 is a graph of the output of a humidity fluctuation battery comparing two types of waterproof and breathable membranes. [Figure 8] FIG. 2 is a perspective view showing the configuration of an electrode. [Figure 9] (a) Cross-sectional view of an electrode consisting of only a long-life layer and (b) a multi-layered electrode consisting of a long-life layer and a highly reactive layer. [Figure 10] 1 is a graph of humidity swing cell charge comparing two electrodes. [Figure 11] 1 is a graph of the charge of humidity swing batteries with and without surfactant added to the electrolyte. DETAILED DESCRIPTION OF THE INVENTION

[0013] A humidity fluctuation battery, which is one embodiment of a humidity fluctuation power generation element according to the present invention, will be described below with reference to Figure 1. Note that the humidity fluctuation power generation element is an element that generates electricity in response to humidity changes, and therefore can also be used as a sensor for detecting humidity changes, but here it will be described as a humidity fluctuation battery.

[0014] As shown in FIG. 1, humidity fluctuating battery 10 includes closed chamber 1, which is filled with aqueous electrolyte 9a and isolated from the environment, and open chamber 2, which is filled with aqueous electrolyte 9b and is open to the moisture in the environment to allow moisture exchange. Closed chamber 1 and open chamber 2 are separated from each other by ion-permeable membrane 3. Electrodes 4a and 4b are inserted into closed chamber 1 and open chamber 2, respectively, so as to contact electrolyte 9a and 9b. In other words, aqueous electrolyte is applied to both sides of ion-permeable membrane 3 along with the electrodes. Electrodes 4a and 4b are connected to wiring 5a and wiring 5b, respectively, for extracting the electromotive force generated between them to the outside. It is also preferable to provide a mesh sheet 14 with multiple openings on the outside of waterproof / breathable membrane 13 to prevent the intrusion of solids from the outside.

[0015] The electrolyte solutions 9a and 9b are aqueous solutions of deliquescent ionic compounds. Therefore, when the open tank 2 is exposed to the environment, it absorbs or releases moisture in response to changes in the humidity of the outside air, changing the ion concentration of the electrolyte solution 9b. Furthermore, chlorides, for example, can be suitably used as the deliquescent ionic compounds.

[0016] Here, closed tank 1 contains electrolyte 9a with a waterproof and moisture-proof membrane / wall, insulating electrolyte 9a from moisture in the external environment. Specifically, closed tank 1 is formed by containing electrolyte 9a in closed tank housing 11, which also serves as a waterproof and moisture-proof membrane / wall. On the other hand, open tank 2 is open to the environment to allow exchange of water vapor with the outside, while still being able to retain aqueous electrolyte inside. Therefore, for example, open tank 2 contains electrolyte 9b with a waterproof and moisture-permeable membrane 13. This makes it possible to prevent leakage of electrolyte 9b while leaving open tank 2 exposed to moisture in the environment.

[0017] The closed and open tanks 1 and 2 are formed by sealing the open ends of bottomed pipes formed by the closed tank housing 11 and the open tank housing 12, which serve as waterproof and moisture-proof walls, with a waterproof and moisture-permeable membrane 13. The bottom and open ends of the resulting internal space are separated by an ion-permeable membrane 3. Preferably, electrolyte 9a is contained so as to fill the bottom-side closed tank 1, ensuring constant contact with the entire surface of the ion-permeable membrane 3 and promoting ion exchange. Meanwhile, electrolyte 9b is contained in the open tank 2 on the open end side, allowing for volumetric changes due to changes in its moisture content as it absorbs and releases moisture. The waterproof and moisture-permeable membrane 13 allows permeation of gas molecules in the air, allowing for volumetric changes even when electrolyte 9b is contained in the open tank 2 so as to form gas pockets, such as air, when its volume is reduced. However, in this embodiment, a flexible waterproof and moisture-permeable membrane 13 is used, as described below. A porous fluororesin, for example, can be used as such a waterproof and moisture-permeable membrane 13.

[0018] As described above, in the humidity fluctuating battery 10, the electrolyte 9b contained in the open tank 2 changes its volume, which in turn changes the height of the liquid surface. To accommodate the change in volume, it is necessary to arrange the waterproof / moisture-permeable membrane 13 so that the volume of the open tank 2 is larger than the maximum volume of the electrolyte 9b.

[0019] On the other hand, it has been found that the shorter the distance between the waterproof and moisture-permeable membrane 13 of the open chamber 2 and the electrolyte 9b, the higher the rate at which water vapor is absorbed from the environment and released into the environment (moisture absorption rate and moisture desorption rate). Furthermore, a higher moisture absorption rate and moisture desorption rate increases the responsiveness of the humidity fluctuating battery 10, improving power generation output. Therefore, by positioning the waterproof and moisture-permeable membrane 13 to minimize the volume of the open chamber 2, the moisture absorption rate and moisture desorption rate can be increased, and changes in the moisture absorption rate and moisture desorption rate can be relatively reduced. In other words, improving the responsiveness of the humidity fluctuating battery 10 and minimizing these changes can enhance operational stability and operational stability against the environment. In particular, it is more preferable to position the waterproof and moisture-permeable membrane 13 so that it is in contact with the electrolyte 9b, as this maximizes the moisture absorption and moisture desorption rates.

[0020] Therefore, as described above, a flexible waterproof / moisture-permeable membrane 13 is used in the humidity fluctuating battery 10. This allows the waterproof / moisture-permeable membrane 13 to deform to follow the electrolyte solution 9b due to its flexibility, even if the volume of the electrolyte solution 9b becomes large relative to the volume of the open chamber 2. In other words, the waterproof / moisture-permeable membrane 13 can be positioned along the surface of the electrolyte solution 9b to reduce the distance therebetween, and can even be positioned so as to come into contact with the surface of the electrolyte solution 9b.

[0021] In particular, it is preferable to pre-deflect the waterproof / moisture-permeable membrane 13, as shown in FIG. 2. Deflecting the membrane allows the waterproof / moisture-permeable membrane 13 to deform to a degree that cannot be achieved by elastic deformation, making it easier to follow the volumetric changes of the electrolyte solution 9b. This makes it easier to position the waterproof / moisture-permeable membrane 13 along the surface of the electrolyte solution 9b, and even to bring the membrane 13 into contact with the surface of the electrolyte solution 9b. While the mesh sheet is omitted from FIG. 2, if a mesh sheet is used, it is preferable that the mesh sheet also be flexible, and furthermore, have elasticity and deflection, so that it can follow the deformation of the waterproof / moisture-permeable membrane that follows the volumetric changes of the electrolyte solution 9b.

[0022] Furthermore, if the area of ​​the waterproof and moisture-permeable membrane 13 facing the open tank 2 exposed to the environment is larger than the area of ​​the ion-permeable membrane 3 separating the closed tank 1 and the open tank 2, this also improves the moisture absorption rate and moisture release rate, which is preferable.

[0023] As described above, when the electrolytic solution 9b is brought into contact with the waterproof / moisture-permeable membrane 13, it is preferable to increase the wettability thereof, as this can increase the moisture absorption and desorption rates. Therefore, for example, it is preferable to provide a coating that increases the wettability with the electrolytic solution 9b on the side of the waterproof / moisture-permeable membrane 13 that comes into contact with the electrolytic solution 9b. Furthermore, the electrolytic solution 9b may contain a surfactant that increases the wettability with the waterproof / moisture-permeable membrane 13.

[0024] With the above configuration, humidity fluctuating battery 10 can generate electricity by changing the ion concentration in open chamber 2 in response to changes in the humidity in the environment, and using the difference in ion concentration as a driving force to perform ion exchange with closed chamber 1. Furthermore, by increasing the moisture absorption rate and moisture release rate as described above, operational stability can be improved, and operational stability against the environment can also be improved.

[0025] Preferably, silver / silver chloride is used for electrodes 4a and 4b, and an aqueous chloride solution is used for electrolyte solutions 9a and 9b. In this case, it is preferable to provide a coating that reduces the transmission of ultraviolet light to waterproof / moisture-permeable membrane 13 to prevent deterioration of the electrodes. Furthermore, it is also preferable to add a desensitizer to electrolyte solution 9b that suppresses the decomposition of silver chloride. Phenosafranine is a suitable desensitizer.

[0026] In such humidity-fluctuating batteries, for example, an ion-exchange membrane that allows the passage of hydrated cations is used as the ion-permeable membrane. The electrostatic repulsion of the fixed negative charge within the membrane prevents anions from penetrating the membrane, allowing only cations to pass through selectively in a hydrated (solvated) state. However, such cation-exchange membranes have some water permeability due to the water contained within them. Depending on the osmotic pressure that changes with the environment, water may pass through in a direction that reduces the ion concentration difference between the open and closed compartments, resulting in self-discharge. Furthermore, such ion-exchange membranes that conduct hydrated cations exhibit reduced ion selectivity for electrolytes with concentrations exceeding the fixed negative charge density, allowing the passage of anions. In the case of humidity-fluctuating batteries, depending on the humidity, such electrolytes may become highly concentrated, resulting in reduced output. In other words, self-discharge and output reduction can occur depending on the environment.

[0027] Therefore, in the humidity fluctuating battery 10 of this embodiment, a solid ceramic electrolyte is used as the ion permeable membrane 3.

[0028] For example, as shown in Figure 2, + B n+ (X - )n+1 In the solid ceramic electrolyte with the structure of X - A, which has weak bonds with ions + Only ions can move through it. In other words, the solid ceramic electrolyte allows only cations to pass through. Therefore, by using a solid ceramic electrolyte as the ion-permeable membrane 3, the humidity fluctuating battery 10 can suppress the permeation of anions and water. In other words, it can suppress self-discharge due to water permeation and output reduction due to permeation of anions.

[0029] Such a solid ceramic electrolyte is, for example, LATP (Li ATP) having a LISICON (lithium superionic conductor) type crystal structure with high water resistance. 1.4 Al 0.4 Ti 1.6 A (PO4)3)-based solid electrolyte can be preferably used, which can chemically stabilize the ion-permeable membrane 3. In addition, the ion-permeable membrane 3 made of a solid ceramic electrolyte is preferably formed into a plate-like body with a thickness of 20 μm or less, which can reduce the internal resistance of the humidity fluctuating battery 10.

[0030] The ion-permeable membrane 3 is fixed within the humidity-varying battery 10 by being sandwiched between the lower support 6a and the upper support 6b. The lower support 6a and the upper support 6b are preferably made of a foam material and a composite containing an electrolyte, which prevents damage to the ion-permeable membrane 3, which is made of a fragile solid ceramic electrolyte, and physically stabilizes the ion-permeable membrane 3. In particular, the ion-permeable membrane 3 is preferably made thin to reduce the internal resistance of the humidity-varying battery 10, but this allows for stable support even for a brittle ion-permeable membrane 3. The lower support 6a and the upper support 6b also serve as sealants for sealing the electrolyte solutions 9a and 9b, respectively. For example, foamed fluororubber can be used as such a foam material.

[0031] [Production test] Next, an example of fabricating a humidity fluctuating battery 10 according to this embodiment will be described.

[0032] First, a method for producing the humidity fluctuating battery 10 will be described with reference to FIGS.

[0033] As shown in FIG. 4, the humidity fluctuating battery 10 can be fabricated by laminating a closed-chamber casing 11 and an open-chamber casing 12 made of resin together with other components, and welding them together.

[0034] Referring also to Figure 5A, a rectangular annular lower support 6a with a 24 x 24 mm opening was placed inside a closed vessel housing 11 made of black ABS resin and shaped like a dish with a roughly rectangular depression in the center. The lower support 6a was made of foamed fluororubber with a hardness of 48 (Type A durometer). 0.15 mL of a 23.2 wt% lithium chloride aqueous solution was poured into the opening of the lower support 6a, which would become the closed vessel 1, and the electrode 4a was immersed in the electrolyte 9a, filling the closed vessel 1 made of the closed vessel housing 11. The electrode 4a was made by printing silver paste in a mesh pattern on both sides of 23 x 23 mm filter paper, baking it, and anodizing it in a hydrochloric acid solution to convert some of the silver to silver chloride. A gold-plated silver wire was then attached to the surface as wiring 5a. A 1-inch square, 20 μm thick LATP solid ceramic electrolyte plate (manufactured by Ohara Inc., LICGC (registered trademark) sintered compact-01) was placed as the ion-permeable membrane 3 to close the opening. Furthermore, an upper support 6b having the same planar shape as the lower support 6a was placed on top of it. The upper support 6b was made of foamed fluororubber with a hardness of 12 (type A durometer).

[0035] As shown in FIG. 5B, an open-tank housing 12 made of transparent polymethyl methacrylate resin is placed on top of the upper support 6b, and a load is applied from above. As a result, the open-tank housing 12 crushes the upper support 6b and the lower support 6a, and its outer periphery abuts against the closed-tank housing 11. The open-tank housing 12 has an opening on its lower side that is the same size as the opening of the upper support 6b, and an opening on its upper side that is wider. This allows the area of ​​the upper opening to be larger than the area of ​​the ion-permeable membrane 3 that separates the closed tank 1 and the open tank 2.

[0036] As shown in FIG. 5C , the closed-tank housing 11 and the open-tank housing 12 were fixed together by laser welding while maintaining the load. As a result, the ion-permeable membrane 3 was supported by the upper support 6b and the lower support 6a and fixed between the open-tank housing 12 and the closed-tank housing 11. This fixation could also be achieved by other methods, such as adhesives, double-sided tape, hot melt adhesive, or ultrasonic welding. The laser penetrates the transparent open-tank housing 12 and irradiates the black closed-tank housing 11, heating the surface of the closed-tank housing 11 that contacts the open-tank housing 12, thereby welding the two thermoplastic resin bodies together. At this time, the wiring 5a was routed to the outside through the gap between the closed-tank housing 11 and the lower support 6a and between the closed-tank housing 11 and the open-tank housing 12.

[0037] 5D, 0.2 mL of a 23.2 wt % aqueous lithium chloride solution as electrolyte 9b was poured into the lower opening of open-tank casing 12, which becomes open tank 2, and the opening of upper support 6b, and electrode 4b was immersed therein to accommodate electrolyte 9b inside open-tank casing 12. Electrode 4b is the same as electrode 4a.

[0038] Finally, as shown in FIG. 5E, a waterproof / moisture-permeable membrane 13 made of a porous fluororesin film and a mesh sheet 14 made of a PET film with honeycomb-shaped openings were placed to cover the upper opening of the open-chamber housing 12. A porous PTFE membrane (POREFLON® Membrane HP-045-30, manufactured by Sumitomo Electric Fine Polymer Co., Ltd.) was used for the waterproof / moisture-permeable membrane 13. The waterproof / moisture-permeable membrane 13 and mesh sheet 14 were attached to the open-chamber housing with double-sided tape. The mesh sheet can also be made of various plastic materials, metal meshes, or punched sheets. The wiring 5b was routed between the waterproof / moisture-permeable membrane 13 and the open-chamber housing 12 and routed to the outside. This completed the humidity-fluctuating battery 10.

[0039] Two types of humidity fluctuation batteries were created as described above. One waterproof / breathable membrane was pre-strained before installation. A platinum film was formed by sputtering on the surface of the bent waterproof / breathable membrane that comes into contact with the electrolyte to enhance wettability with the electrolyte. 0.01 wt% of 1-octanol was added to the electrolyte 9b in the open chamber 2 where the waterproof / breathable membrane was bent as a surfactant to enhance wettability with the waterproof / breathable membrane. The other waterproof / breathable membrane was attached as a comparative example, stretched from the periphery to prevent bending, to obtain a humidity fluctuation battery. In the comparative example, no coating or surfactant to enhance wettability was used.

[0040] Here, as shown in Figure 6, to pre-deflect the waterproof / moisture-permeable membrane 13, pressure was applied using water to deform it. More specifically, the waterproof / moisture-permeable membrane 13 was placed on a plate 22 having a through-hole 22a in the center, and its periphery was fixed and sealed to the plate 22 with a frame 21. Water was then poured through the through-hole 22a to apply pressure. This allowed the waterproof / moisture-permeable membrane 13 to be stretched three-dimensionally and deflected.

[0041] [Comparative Test (1)] Next, a test was conducted to investigate the performance of the two types of humidity fluctuation batteries obtained above, and the results will be described.

[0042] Figure 7 shows the results of measuring the open-circuit voltage when humidity changes were applied to the two types of humidity fluctuation batteries we fabricated. The humidity fluctuation batteries were placed in a constant-temperature, constant-humidity chamber at 25°C, and humidity was changed by alternating between 30% and 90% every four hours. As a result, the humidity fluctuation battery in which the waterproof and breathable membrane 13 was deflected so that it was in contact with the electrolyte (see "close contact" in the same figure) achieved a maximum output that was approximately 1.8 times higher than the humidity fluctuation battery in which the membrane was not deflected (see "unclosed" in the same figure).

[0043] The platinum coating provided on the waterproof / breathable film can also suppress transmission of ultraviolet rays, thereby suppressing deterioration of the electrodes 4a and 4b due to ultraviolet rays.

[0044] [Comparative Test (2)] Furthermore, two types of electrodes were fabricated and a comparative test was carried out using a similar humidity fluctuation battery, and the results are described below.

[0045] As shown in FIG. 8, the electrodes are made by printing silver paste 42 in a mesh pattern on both sides of filter paper 41, baking it, and anodizing it to form silver / silver chloride electrodes.

[0046] In particular, as shown in Figure 9(a), one electrode was formed as a single layer on both sides of filter paper 41 using a resin-containing silver paste (RA FS 059 S, manufactured by Toyo Ink Co., Ltd.). This silver paste contains micrometer-sized silver particles and resin, and electrical conductivity is achieved through contact between the silver particles. The inclusion of resin makes it difficult for the electrolyte to penetrate deep into the electrode, reducing reactivity, but also making it less susceptible to decomposition and achieving a relatively long life. This layer will be referred to as long-life layer 42a.

[0047] As shown in Figure 1(b), the other electrode was formed on both sides of filter paper 41, with a long-life layer 42a containing the same resin as above sandwiched between layers of resin-free silver paste (DNS409S, manufactured by Daicel Corporation) to form three layers on each side. This resin-free silver paste is made by dispersing nanometer-sized silver particles in a solvent. When fired, the silver particles sinter to form a layer of resin-free pure silver film. This layer increases reactivity by allowing the electrolyte to easily penetrate into the interior, but it also promotes electrode reactions within the layer, making it prone to decomposition and breakage. This layer is referred to as the high-reactivity layer 42b.

[0048] As shown in Figure 10, humidity-varying batteries using these two types of electrodes were placed in a thermo-hygrostat and connected to a 10 Ω load resistor. The temperature was set to 25°C and humidity was varied to generate electricity. As described above, the humidity was alternately varied between 30% and 90% every four hours. The amplitude of the charge output from the humidity-varying battery using an electrode with only the long-life layer 42a gradually decreased over time. On the other hand, the amplitude of the charge output from the humidity-varying battery using an electrode with a multilayer structure of the long-life layer 42a and the highly reactive layer 42b did not decrease significantly. In other words, the use of the latter multilayer electrode, consisting of a silver / silver chloride layer and a layer of silver / silver chloride mixed with resin, allows for stable, high output. This improves operational stability and environmental stability.

[0049] [Comparative Test (3)] Furthermore, as shown in Figure 11, we compared the presence or absence of a desensitizer in the electrolyte. One humidity fluctuation battery was fabricated with 0.01 wt% of phenosafranine added as a desensitizer to the electrolyte, while the other humidity fluctuation battery was fabricated without adding a desensitizer to the electrolyte. Then, the two humidity fluctuation batteries fabricated were subjected to a test using a wavelength of 254 nm and an intensity of 610 μW / cm. 2 The two types of humidity fluctuation batteries were each placed in a constant temperature and humidity chamber, and as in Comparative Test (2), a load resistance of 10 Ω was connected and humidity was changed to generate electricity, and the output charge was measured. The output charge of the humidity fluctuation battery without the addition of a desensitizer was biased to the positive side compared to the humidity fluctuation battery with the addition of a desensitizer. This is because the silver chloride on the electrode on the open chamber side was decomposed and returned to silver by the irradiation of ultraviolet light, and the amount of silver in the electrode increased, resulting in Ag+Cl at low humidity. - ⇒This is thought to be due to the fact that the chemical reaction of AgCl becomes more active. In other words, adding a desensitizer suppresses the photodecomposition of silver chloride, and thus the deterioration of humidity-varying batteries can be suppressed.

[0050] While the present invention has been described above with reference to exemplary embodiments and modifications thereof, the present invention is not necessarily limited thereto, and those skilled in the art will be able to find various alternative embodiments and modifications without departing from the spirit of the present invention or the scope of the appended claims. For example, depending on the combination of electrodes and electrolytes, an anion-permeable solid ceramic electrolyte can also be used as the ion-permeable membrane. [Explanation of symbols]

[0051] 1 Closed tank 2 Open tank 3. Ion-permeable membrane 4a, 4b electrode 9a, 9b Electrolyte 10 Humidity-varying battery

Claims

1. A humidity fluctuation power generation element that generates electromotive force by utilizing humidity fluctuations in the environment, An aqueous electrolyte solution consisting of an aqueous solution of a deliquescent ionic compound is accommodated on each side of the ion-permeable membrane together with an electrode, On one side of the ion-permeable membrane, the aqueous electrolyte is accommodated in a waterproof and moisture-permeable membrane that allows water vapor to pass through above the ion-permeable membrane; A humidity fluctuation power generation element characterized in that on the other side of the ion-permeable membrane, the aqueous electrolyte is contained by a waterproof and moisture-proof membrane / wall that blocks at least moisture in the environment on top of the ion-permeable membrane, and the waterproof and moisture-permeable membrane is flexible and is provided along the surface of the aqueous electrolyte.

2. The humidity fluctuation power generation element according to claim 1, characterized in that the open end of the housing, which is a bottomed tubular body made of the waterproof and moisture-proof membrane / wall, is closed with the waterproof and moisture-permeable membrane, the bottom side of the formed internal space is separated from the open end side by the ion-permeable membrane, the bottom side is filled with the aqueous electrolyte, and the open end side also contains the aqueous electrolyte.

3. 3. The humidity fluctuation power generation element according to claim 2, wherein the waterproof and moisture-permeable film is made of porous fluororesin.

4. 4. The humidity fluctuation power generation element according to claim 1, wherein the waterproof and moisture-permeable membrane has a coating on the side that comes into contact with the aqueous electrolyte to enhance wettability with the aqueous electrolyte.

5. 2. The humidity fluctuation power generation element according to claim 1, wherein the aqueous electrolyte contains a surfactant that enhances wettability with the waterproof and moisture-permeable membrane.

6. 2. The humidity fluctuation power generating element according to claim 1, wherein the electrodes are made of silver / silver chloride, and the aqueous electrolyte is an aqueous chloride solution.

7. 7. The humidity fluctuation power generating element according to claim 6, wherein the electrode is a multi-layered structure including a silver / silver chloride layer and a layer of silver / silver chloride mixed with a resin.

8. 7. The humidity fluctuation power generation element according to claim 6, wherein the waterproof and moisture-permeable film is provided with a coating that reduces the transmission of ultraviolet rays.

9. 7. The humidity fluctuation power generating element according to claim 6, wherein the aqueous electrolyte contains a desensitizer that suppresses decomposition of silver chloride.

10. 10. The humidity fluctuation power generating element according to claim 9, wherein the desensitizing agent is phenosafranine.

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