JP7756424B2 - Flexible thermochemical battery and flexible thermochemical battery module - Google Patents

Description

The present invention relates to a thermochemical battery that can convert thermal energy into electrical energy (power generation) via chemical energy, and in particular to a thermochemical battery that has been made flexible.

Thermoelectric converts thermal energy directly into electrical energy, and can produce electricity continuously if there is a heat source. On the other hand, batteries generate electrical energy using chemical reactions. Because thermochemical batteries generate electricity through a chemical reaction that uses heat, they have the advantage of being able to produce a higher voltage than thermoelectric conversion, which converts heat directly into electricity.

Specifically, some thermo-electrochemical cells generate electricity by using chemical reactions caused by thermal energy in the presence of a heat source (Non-Patent Documents 1 and 3). On the other hand, some thermo-chemical cells can be used as batteries by using chemical reactions caused by thermal energy to alternately maintain high and low temperature locations (Non-Patent Documents 2 and 3). The former can generate electricity semi-permanently and continuously, while the latter can be used repeatedly by alternately maintaining them in a state with a heat source (high temperature) and a state without a heat source (low temperature).

A thermochemical battery basically consists of two electrodes, a positive electrode and a negative electrode, and an aqueous electrolyte between them. There are two operating modes. One, as described in Non-Patent Documents 1 and 3, is a type in which, when there is a temperature difference between the two electrodes, a difference in the rate of chemical reactions causes a difference in carrier concentration in the electrolyte, generating a potential difference (hereafter referred to as the power generation type). The other, as described in Non-Patent Documents 2 and 3, is a type in which different types of electrolytes are separated into upper and lower or left and right sections by a separator. When the entire system, including the two electrodes, is heated, a potential difference is generated due to the difference in chemical reactions above and below (left and right) of the separator. In low-temperature locations, the reverse reaction occurs (current flow direction is reversed), generating a potential difference (hereafter referred to as the charging type). In either case, a surface reaction between ions and electrons is required on the electrode surface in contact with the electrolyte, necessitating the selection of an electrode.

For example, metals, particularly precious metals such as platinum, which have high catalytic activity, are often used for both electrodes of thermochemical batteries (Non-Patent Document 4). Some batteries also use a carbonized film for one electrode and platinum for the other (Patent Document 1). Furthermore, the inventors have invented a thermochemical battery that uses an organic conductive film electrode as the electrode, which has properties equal to or better than those of platinum, and can be used as the power generation type or charging type thermochemical battery (Patent Document 2).

Japanese Unexamined Patent Publication No. 8-171918 Patent No. 6732227

“Seebeck coefficients in ionic liquids prospects for themo-electrochemical cells”, T.J.Abraham, D.R.MacFarlane and J.M.Pringle, Chem. Commun., 47, (2011) pp.6260-6262. “Charging-free electrochemical system for harvesting low-grade thermal energy”, Y. ang, S.W.Lee, H.Ghasemi, J.Loomis, X.Li, D.Kraemer, G.Zheng, Y.Cui and G.Chen, PNAS, 111 (48), (2014), pp.17011-17016. “Poly(3,4-Ethylene Dioxythiophene)/Poly(Styrene Sulfonate) Electrodes in Electrochemical Cells for Harvesting Waste Heat”, Y. Wang, M. Mukaida, K. Kirihara, L. Lyu, and Q. Wei, Energy Technology, (2019), pp.1900998(1 of 8)-1900998(8 of 8). “Review of Thermally Regenerative Electrochemical Systems”, H.L.Chum and R.A.Osteryoung, Synopsis and Executive Summary, vol.1, Solar Energy Research Institute, (1980) pp.1-53.

As such, thermochemical batteries are convenient and environmentally friendly because they do not require wiring for charging, can generate sufficient power continuously, and can be used repeatedly. Therefore, it is expected that the range of applications of thermochemical batteries will expand in the future, such as being able to be carried around and used in various places and being installed in mobile objects.
On the other hand, thermochemical batteries contain an aqueous electrolyte inside, so they have a rigid structure to prevent leakage of the electrolyte, and they are not suitable for use on large, curved, or uneven surfaces, which limits their range of application.

The objective of the present invention is to provide a thermochemical battery and a thermochemical battery module that are highly versatile and can be used in a variety of locations and for a variety of purposes, while suppressing electrolyte leakage in a thermochemical battery that uses an aqueous electrolyte.

In thermochemical batteries, to generate power from a low-temperature heat source, a battery that can adapt to a wide surface is effective so that it can accommodate a relatively wide range of heat sources. However, because thermochemical batteries use an aqueous solution electrolyte, they have a rigid structure to prevent leakage. However, according to the present invention, the sealing body that contains the aqueous solution electrolyte is flexible, and the entire thermochemical battery is flexible, making it possible to adapt to a wide range of curved surfaces and uneven surfaces. Specifically, this problem is solved by the following means.

(1) A thermochemical battery comprising a pair of electrodes and an aqueous electrolyte present between and in contact with the pair of electrodes, capable of generating electricity when there is a temperature gradient difference between the pair of electrodes, characterized in that the battery has a flexible sealing body containing the aqueous electrolyte therein.
(2) A thermochemical battery comprising a pair of electrodes and a pair of aqueous solution electrolytes present between the pair of electrodes in contact with the electrodes and separated by a separator, capable of generating electricity through an oxidation-reduction reaction between the pair of aqueous solution electrolytes and the pair of aqueous solution electrolytes in the vicinity of the surfaces of the pair of electrodes when the pair of aqueous solution electrolytes are at a predetermined temperature condition, characterized in that the battery is provided with a flexible sealing body containing the aqueous solution electrolytes therein.
As described above, flexible thermochemical batteries are capable of continuous power generation, repeated use, and can be adapted to uneven surfaces, making them suitable for use in a variety of locations.
(3) The flexible thermochemical battery according to (1) or (2), wherein the sealing body comprises the pair of flexible electrodes and a flexible and insulating case disposed between the ends of the pair of flexible electrodes, the case containing the aqueous electrolyte, and the case having flexibility and insulating properties. Note that the term "between the ends of the pair of electrodes" also refers to the area between the outer edges of the pair of electrodes.
According to this configuration, both the electrodes and the insulating case disposed between the ends of the electrodes are flexible, so that the thermochemical battery has excellent flexibility while maintaining its strength.

(4) The thermochemical battery according to (3), wherein the pair of flexible electrodes is a carbon sheet or a conductive polymer sheet.
According to this configuration, the electrode is in a sheet form, which makes it easy to handle and leads to a thinner and lighter flexible thermochemical battery as a whole.
(5) The flexible thermochemical battery according to (3) or (4), wherein the flexible and insulating case is made of rubber.
According to this configuration, since the case is made of a rubber material, the entire thermochemical battery can more easily fit on an uneven surface.
(6) The flexible thermochemical battery according to (4) or (5), characterized in that a conductive polymer sheet is provided on the electrolyte-side surfaces of the pair of carbon sheet electrodes.
According to this configuration, by disposing the conductive polymer material on the electrolyte side of the electrode, the oxidation-reduction reaction of the electrolyte in the aqueous solution is further activated, improving the characteristics of the battery.

(7) The flexible thermochemical battery according to any one of (3) to (6), further comprising an adhesive member between the electrode and the case, for bonding the electrode and the case together. With this configuration, the electrode and the case are firmly bonded together.
(8) In the flexible thermochemical battery according to (7), the adhesive member comprises an adhesive on the electrode side, an adhesive on the case side, and a flexible substrate provided between the adhesive on the electrode side and the adhesive on the case side. This configuration allows the case and the electrodes to be bonded with different types of adhesives.

(9) In the flexible thermochemical battery according to (7), the adhesive member comprises: an adhesive member having an adhesive on the electrode side; and an adhesive provided between the case and the adhesive member, bonding the adhesive member to the case; or an adhesive member having an adhesive on the case side; and an adhesive provided between the electrode and the adhesive member, bonding the adhesive member to the electrode. According to this configuration, when different types of adhesives are used to bond the case and the electrode, the case and the electrode can be bonded simply and easily by using an adhesive member on the electrode side or the case side.
(10) The flexible thermochemical battery according to (8) or (9), characterized in that the flexible and insulating case is made of silicone rubber, the pair of flexible electrodes are carbon sheets or conductive polymer sheets, the adhesive or pressure-sensitive adhesive on the electrode side is a non-silicone adhesive, and the adhesive or pressure-sensitive adhesive on the case side is a silicone adhesive. Using silicone rubber for the case, which has particularly excellent heat resistance and chemical resistance and a wide range of flexibility options, improves the durability of the thermochemical battery and also enables the desired flexibility to be achieved. Furthermore, by selecting an adhesive appropriate for the material, the case and electrodes can be firmly bonded.

(11) A thermochemical battery module comprising a plurality of flexible thermochemical batteries according to any one of (1) to (10) electrically connected in series, which allows stable high power generation from a wide area of a low-temperature heat source.
(12) The flexible thermochemical battery module according to (11), characterized in that, between adjacent flexible thermochemical batteries connected in series, one of the pair of electrodes of one flexible thermochemical battery partially overlaps with the opposite electrode of the pair of electrodes of the other flexible thermochemical battery in a plan view, and a conductive member is provided at the overlapping portion to connect the one electrode to the opposite electrode. By providing a conductive member at the overlapping portion of the electrodes of adjacent thermochemical batteries, the conductive members can be easily connected and the strength is excellent. Furthermore, since adjacent thermochemical batteries can be arranged closely together, the module can be compact and high-power.
(13) The thermochemical battery module according to (11) or (12), characterized in that the sealed body of the flexible thermochemical battery includes a pair of flexible electrodes and a flexible, insulating case disposed between the ends of the pair of flexible electrodes and containing the aqueous electrolyte. Between adjacent series-connected flexible thermochemical batteries, the adjacent sidewall of the case of one flexible thermochemical battery also serves as the adjacent sidewall of the case of the other flexible thermochemical battery. A conductive member is provided within the sidewall, connecting one of the pair of electrodes of one flexible thermochemical battery to the opposite electrode of the other flexible thermochemical battery. The common sidewall of the adjacent cases between adjacent flexible thermochemical batteries allows for a large amount of electrolyte and a large electrode surface area, enabling high power generation without increasing the size. Furthermore, the overall thermochemical battery module has a simple structure, leading to weight and cost savings. Furthermore, by providing the conductive members inside the side walls of the case, the conductive members are protected and the case has excellent impact resistance.

(14) A flexible thermochemical battery module comprising: a cylindrical outer frame; partition members that divide the interior of the outer frame into a plurality of compartments; a flexible and insulating case; a pair of flexible electrodes that close both ends of the opening of each compartment of the case; an aqueous electrolyte that fills each compartment and is sealed by the case and the electrodes; and a conductive member that electrically connects the plurality of compartments in series, the conductive member being provided inside the partition member and connecting the electrode on one end of the opening of one of the adjacent compartments to the electrode on the other end of the opening of the other compartment; and capable of generating electricity when there is a temperature gradient difference between the electrode on one end of the opening of each compartment and the electrode on the other end of the opening.
(15) A flexible thermochemical battery module comprising: a cylindrical outer frame and partition members dividing the interior of the outer frame into a plurality of compartments; a flexible and insulating case; a pair of flexible electrodes sealing both ends of the opening of each compartment of the case; a pair of aqueous solution electrolytes filled in each compartment and sealed by the case and the electrodes, separated by a separator arranged horizontally to the electrode surfaces; and a conductive member electrically connecting the plurality of compartments in series, the conductive member being provided inside the partition member and connecting an electrode on one end of an opening of one of the adjacent compartments to an electrode on the other end of the opening of the other compartment; and capable of generating electricity by an oxidation-reduction reaction between the electrolyte of each pair of aqueous solutions and the surfaces of each pair of electrodes when the electrolyte of each pair of aqueous solutions in each compartment is at a predetermined temperature condition.
(16) A flexible thermochemical battery module according to (14) or (15), characterized in that the partition member, the portion to which the conductive member of the electrode on one end of the opening of one compartment is connected, and the portion to which the conductive member of the electrode on the other end of the opening of the other compartment is connected overlap in a planar view.
By unitizing thermochemical batteries consisting of individual compartments, there are no gaps between the thermochemical batteries and no lost area, compared to a thermochemical battery module made up of multiple independent thermochemical batteries connected together, thereby improving the output density of the thermochemical battery module.

The thermochemical battery of the present invention is flexible, allowing it to be placed on curved or uneven surfaces, making it highly versatile and expanding its range of applications. Furthermore, the thermochemical battery module of the present invention can be used on a wide surface of a low-temperature heat source, making it possible to obtain high power.

1 is a diagram showing the configuration of a power generation type battery and the power generation principle. FIG. 1 is a diagram showing the configuration of a rechargeable battery and the principle of power generation (in an equilibrium state). 1 is a diagram showing the configuration of a rechargeable battery and the principle of power generation. 1A is a plan view of a thermochemical battery according to a first embodiment, and FIG. 1B is a plan view of a case portion thereof. 4A is a side view (partial cross section) of the thermochemical battery shown in FIG. 4A viewed from various directions. FIG. 2 is an enlarged side view (schematic diagram) of a joint portion between an electrode and a case. FIG. 1 is a side view (partial cross section) of a rechargeable flexible thermochemical battery. 1A is a plan view of a thermochemical battery module according to a second embodiment, and FIG. 1B is a side view (partial cross section) thereof. 10A is a plan view of a thermochemical battery module according to a third embodiment, and FIG. 10B is a side view (partial cross section) thereof. 10A is a plan view of a thermochemical battery module according to a fourth embodiment, and FIG. 10B is a side view (partial cross section) thereof. 10A is a plan view of a thermochemical battery module according to a fifth embodiment, and FIG. 10B is a plan view of a case portion thereof. 11(A) is a side view (partial cross section) of the thermochemical battery module shown in FIG. 11(A) as viewed from various directions. Photograph of a flexible thermochemical battery. FIG. 1 is a diagram showing an example of output from a flexible thermochemical battery (power generation type). FIG. 10 is a diagram showing an example of output from a flexible thermochemical battery (rechargeable type). FIG. 10 is a diagram showing an example of the output of a flexible thermochemical battery module.

FIG. 1 shows the configuration of a power generating type battery and a diagram of the power generation principle.
Electrodes (for example, carbon sheets or conductive polymer sheets) 1 are electrically connected via a resistor (load) and are in contact with the electrolyte 3 at both ends of the electrolyte so as to sandwich it.

As shown in FIG. 1A, when there is no temperature difference between the electrodes 1 at both ends, the ion concentration inside the electrolyte is uniform and no potential difference occurs.
A, A ^3- , A ^4- , and e ⁻ represent a general atomic symbol, a trivalent anion of the atom, a tetravalent anion of the atom, and an electron, respectively.
Here, trivalent and tetravalent ions are exemplified, but the valence is not limited. Also, examples of A ^3- and A ^4- include CN ^- , CN ^2- , Fe(CN) ₆ ^3- , and Fe(CN) ₆ ^4- . It is considered that ions with a large formula weight are better, as they transport a large amount of energy when they move. However, when using a solution as an electrolyte, ions that are too large will not dissolve, so a balance must be struck.

1(B) shows an example where there is a temperature difference between the electrodes 1 at both ends (the bottom is high temperature and the top is low temperature in the figure). On the surface of the upper and lower electrode 1, ions (A ^4- ) in the electrolyte react on the high temperature side to become ions (A ^3- ) whose valence has changed and electrons (e ^- ) and electrons are generated (oxidation), and on the low temperature side, electrons flow in and the ions whose valence has changed react to become ions with the original valence (A ^4- ) (reduction).
In the electrolyte, differences in chemical reactions at the surfaces of both electrodes create differences in ion concentration, which leads to interdiffusion of ions.
On the other hand, the generated electrons move from the high-temperature electrode to the low-temperature side along the external conductor 2, generating electricity, with the high-temperature side becoming the cathode and the low-temperature side becoming the anode. Thus, in a power-generating battery, the current flows in one direction.

2 and 3 show the configuration of a rechargeable battery and its power generation principle. In this specification, the term "rechargeable" is used to distinguish it from the power generation type battery (where the current flows in one direction), and refers to a thermochemical battery (where the current flows in two directions) in which the current direction changes depending on the temperature, as will be described later. Specifically, this refers to a type of thermochemical battery in which the current direction alternates between temperatures higher and lower than a certain temperature, allowing for repeated use.
The electrodes 1 at both ends are electrically connected via a resistor (load), and electrolytes 3a and 3b separated by a separating material (ion-permeable membrane) 4 are in contact with one end opposite the separating material 4, respectively.

Although the electrolytes 3a and 3b are different types of electrolytes, they each have a common ion (cation or anion) (A ⁺ in the illustrated example). The electrolytes 3a and 3b undergo different reactions, and the temperature dependence of their reaction rates differs. For example, at a certain temperature, the reaction rates of the electrolytes 3a and 3b are the same (equilibrium state), and at other temperatures, the reaction rates of the electrolytes 3a and 3b differ. It is assumed that the reaction rate of the electrolyte 3a (or the reaction rate of the electrolyte 3b) is higher at temperatures higher than the equilibrium state, and the reaction rate of the electrolyte 3b (or the reaction rate of the electrolyte 3a) is higher at temperatures lower than the equilibrium state. In this case, the reaction of the electrolyte 3a (or the electrolyte 3b) occurs preferentially at temperatures higher than the equilibrium state, and the reaction of the electrolyte 3b (or the electrolyte 3a) occurs preferentially at temperatures lower than the equilibrium state. It should be noted that even if there is a certain temperature range at the equilibrium state, the equilibrium state can be considered to be a temperature at which no reaction can be confirmed.

When a reaction occurs between electrolytes 3a and 3b, the separation material 4 allows the common ions to pass through. If the common ions are cations, the separation material 4 is a cation-permeable membrane (cation exchange membrane), and if the common ions are anions, the separation material 4 is an anion-permeable membrane (anion exchange membrane).

A, B, and C are general atomic symbols.
e ⁻ represents an electron, and A ⁺ , B ⁻ , B ²⁻ , C ⁻ , and C ²⁻ represent ions and ions with changed valence.
Possible cations include Fe ²⁺ , Fe ³⁺ , Cu ⁺ , Cu ²⁺ , Ag ⁺ , Pb ²⁺ , Pb ⁴⁺ , etc., and possible anions include CN ^- , CN ^2- , Fe(CN) ₆ ^3- , Fe(CN) ₆ ^4- , etc. The valence of the ions, such as monovalent and divalent, is used as an example to explain the principle, and is not actually limited.

Figure 2 shows the state of electrolytes 3a and 3b under temperature conditions (the equilibrium state) where there is no difference in the reaction rates of electrolytes 3a and 3b. In this state, no ion transmission occurs between electrolytes 3a and 3b, and no electromotive force is generated.

For example, if the reaction rate in electrolyte 3a is higher than that in electrolyte 3b at a temperature higher than the equilibrium temperature, heating the entire system as shown in Figure 3(A) causes the oxidation reaction in electrolyte 3a (A ₂ B → AB + A ⁺ + e ^- ) to become dominant, generating A ⁺ and electrons. Electrons generated at lower electrode 1 reach upper electrode 1 via external conductive wire 2. In this environment, electrons flow from lower electrode 1 to upper electrode 1, making the lower electrode a cathode and the upper electrode an anode, generating electricity and utilizing the current flowing at this time. Furthermore, A ⁺ increases in concentration in electrolyte 3a, and moves through separator 4 to upper electrolyte 3b. In electrolyte 3b, a reduction reaction (AC + A ⁺ + e ^- → A ₂ C) occurs using the A ⁺ that has diffused and permeated and the electrons that have flowed to upper electrode 1. Then, the current stops due to ion saturation (when A ⁺ ions no longer move from the electrolyte 3a to the electrolyte 3b).

On the other hand, as shown in Figure 3(B), when the temperature is maintained lower than the equilibrium state, the reverse reaction of Figure 3(A) occurs, and current flows in the opposite direction to that shown in Figure 3(A). In other words, when the temperature is lower than that of the equilibrium state, the reaction rate of electrolyte 3b is greater than that of electrolyte 3a. Therefore, A ₂ C → AC + A ⁺ + e ^- (oxidation reaction) occurs in electrolyte 3b, and A ⁺ moves through separator 4 to the lower electrolyte 3a, and electrons flow from the upper electrode 1 to the lower electrode 1 via external conductive wire 2. In other words, the upper side becomes the cathode and the lower side becomes the anode, generating electricity and causing current to flow in the opposite direction to that shown in Figure 3(A), which can be utilized. In this case, too, current stops flowing due to ion saturation.

Then, by keeping the entire device in different temperature environments (for example, by connecting it to and disconnecting it from a heat source), the steps in Figure 3(A) and Figure 3(B) can be repeated, allowing for repeated use. In other words, the device generates electricity in response to changes in the ambient temperature of the entire device.

(Embodiment 1)
FIG. 4 shows a plan view of the flexible thermochemical battery of this embodiment (FIG. 4(A)) and a plan view of the case (FIG. 4(B)), and FIG. 5 shows side views as viewed from each direction (arrows A-C) of FIG. 4(A). For ease of understanding, the case portion is shown in cross section. Also, the lower electrodes are omitted from the plan view. This is also common to the other drawings. FIG. 6 shows an enlarged side view (schematic diagram) of the joint between the electrode and the case. This thermochemical battery corresponds to the power generation type described above. FIG. 7 shows a side view (partial cross section) of a rechargeable flexible thermochemical battery. The plan view of the rechargeable type thermochemical battery is the same as that of the power generation type thermochemical battery (FIG. 4).

The thermochemical battery 5 comprises an aqueous electrolyte 30 and a flexible sealing body containing the electrolyte 30. The sealing body prevents leakage of the aqueous electrolyte (also called electrolyte solution) 30 to the outside, i.e., provides a liquid-tight seal. The sealing body is formed from a pair of flexible electrodes 10 sandwiching the electrolyte solution 30, and a flexible, insulating case 20 positioned between the ends of the pair of electrodes 10 and containing the electrolyte solution. Because the electrolyte 30 is an aqueous solution and the sealing body that fills and contains the electrolyte 30 forms the outer shape of the thermochemical battery 5, the entire thermochemical battery is flexible, allowing it to adapt to large, curved, or uneven surfaces. Note that flexibility refers to flexibility, but also refers to the property of being easily deformed when external force is applied, for example, with a finger. Each component is described in detail below.

(electrolyte)
The electrolyte 30 can be any redox couple (a pair consisting of two types of ions that undergo an oxidation-reduction reaction) that can generate electricity, and can be applied to any thermochemical battery that uses an aqueous electrolyte. Therefore, it can be used not only for the power generation type but also for the charging type. Furthermore, redox couples often contain a metal element or a halogen element from the viewpoint of chemical stability.

Examples include iron (II) ions and iron (III) ions, cobalt (II) ions and cobalt (III) ions, iodide ions (I ⁻ ) and triiodide ions, ferrocyanide ions and ferricyanide ions, cobalt tris(bipyridine) (II) and cobalt tris(bipyridine) (III), etc. Among these, the use of a redox couple consisting of ferrocyanide ions (potassium ferrocyanide, K ₄ Fe(CN) ₆ ) and ferricyanide ions (potassium ferricyanide, K ₃ Fe(CN) ₆ ) is preferred because of the large voltage and ionic conductivity that can be obtained.

Note that gel-like (semi-solid) electrolytes are not included in the aqueous electrolyte 30. Aqueous electrolytes have better ionic conductivity and superior battery characteristics than gel-like electrolytes.
Additives may be added to the electrolyte 30 for purposes such as improving the electromotive force of the thermochemical battery. For example, the thermoelectric power can be improved by using additives such as guanidinium chloride (GdmCl), betaine (Bet, or more specifically, trimethylglycine), aminoguanidine chloride (AdmCl), and metformin chloride (MfmCl). Other additives include ionic liquids (e.g., 1-ethyl-3-methylimidazolium chloride ([EMIM]Cl)). While additives may or may not be used, guanidinium chloride is particularly suitable for improving electromotive force when ferrocyanide ions are used as the electrolyte, due to its strong interaction with the ferrocyanide ions, resulting in a large electromotive force.

(case)
The case 20 is a cylindrical frame made of a flexible and insulating material. While the example shown in FIG. 4B shows a rectangular frame, the shape of the case 20 is not particularly limited, and may be circular, another polygonal shape, or a shape including curves and straight lines. The case 20 is also not particularly limited as long as it is made of a flexible and insulating material, and may be made of resin or general rubber. Examples of the material include various general-purpose or special synthetic rubbers, such as natural rubber, styrene butadiene rubber, chloroprene rubber, acrylonitrile rubber, butyl rubber, ethylene propylene rubber, urethane rubber, fluororubber, chlorosulfonated polyethylene rubber, and silicone rubber (hereinafter referred to as silicone), and these may be used alone or in combination.

Of these types, fluororubber and silicone are preferred from the perspective of heat resistance. For example, silicone can be used up to 200°C (temporarily up to 300°C). Silicone is also particularly preferred from the perspective of chemical resistance (reactivity with electrolytes), as it excels. Furthermore, the flexibility of silicone can be controlled by the ratio of monomer (skeleton agent) and crosslinking agent (binder) during production, so there is a wide range of flexibility options available.

Furthermore, forming the case 20 from such a flexible material leads to weight and cost reductions for the entire thermochemical battery. Furthermore, the case 20 forms the framework of the sealing body and functions as a pillar, and the flexibility of the case 20 makes it easier for the thermochemical battery to fit on curved or uneven surfaces.

(electrode)
The pair of electrodes 10 serve as both the bottom and the lid of the case 20, and are arranged so as to contact the upper or lower end of the opening of the case 20, i.e., to close the openings at both ends, as shown in FIG.

The electrode 10 may be made of any flexible, electrically conductive material. Examples include carbon and conductive polymers. Carbon electrodes are particularly preferred because they are highly corrosion-resistant, electrically conductive, and inexpensive. Thin-film or sheet-like electrodes, such as carbon sheets (graphite sheets or carbon nanotube (CNT) sheets) and conductive polymer sheets, are also preferred because they are easy to handle and contribute to the overall thinning and weight reduction of the thermochemical battery. The use of sheet-like electrodes also allows the thermochemical battery to fit more easily on large, curved, or uneven surfaces. The graphite sheets, CNT sheets, conductive polymer sheets, and the like may be used alone or in combination. For example, a graphite sheet may be coated with CNT, which has excellent electrical properties.

When using carbon electrodes, a conductive polymer material may be placed on the electrolyte-side surface of the carbon electrode (excluding the surface that interfaces with the case). For example, placing a conductive polymer sheet such as PEDOT/PSS (poly(3,4-ethylenedioxythiophene) doped with poly(4-styrenesulfonic acid)) on the electrolyte-side surface of a graphite sheet or CNT sheet is preferable, as this further activates the redox reaction and improves the battery's characteristics. Note that while it is preferable to place the conductive polymer material on both of the pair of electrodes 10, it may also be placed on one of the electrodes 10.

Furthermore, when using a sheet-type electrode such as a carbon sheet, coating the surface of the sheet-type electrode with a conductive polymer film or attaching a conductive polymer sheet allows the conductive polymer material to adhere to the electrode, improving conductivity. A conductive polymer film can be easily formed by spraying a conductive polymer filler onto the sheet-type electrode. Furthermore, when using a conductive polymer sheet, manufacturing is easy as it can be simply attached.

(External connection electrode)
External connection electrodes 40 are connected to the upper and lower electrodes 10, and an electrical circuit can be formed by connecting a device (not shown) to the external connection electrodes 40. The external connection electrodes 40 are not necessary; they can be connected to the upper and lower electrodes 10 as long as the device can be connected to them. The external connection electrodes 40 can be made of any flexible and conductive material, including conductive carbon fiber, fibers impregnated with a conductive polymer, or metal wire. One end of the external connection electrodes 40 is connected to the upper and lower electrodes, respectively, and the other end is connected to the device. The method of connecting the external connection electrodes 40 to the electrodes 10 and the device is not particularly limited, and can be welding, a detachable fastener such as a clip, or adhesive bonding with a conductive adhesive. Examples of conductive adhesives that can be used include acrylic, epoxy, or urethane adhesives with conductive components such as copper or silver dispersed therein.

(Adhesive member)
By interposing an adhesive member 50 (FIG. 6) between the electrode 10 and the case 20, the electrode 10 and the case 20 are firmly bonded together, enhancing the sealing effect.
The adhesive member 50 may be any material that can join the case 20 and the electrode 10 and prevent leakage of the electrolyte solution 30. For example, an adhesive or an adhesive tape (adhesive member) having an adhesive (adhesive) on one or both sides may be used alone or in combination. Appropriate adhesives and adhesive methods may be selected depending on the type of case and electrode.

For example, if silicone is used as the material for the case 20, it is preferable to use a silicone-based adhesive, which has better adhesive properties, rather than non-silicone adhesives such as acrylic, epoxy, or urethane-based adhesives. On the other hand, if a carbon electrode such as a carbon sheet or a conductive polymer material is used for the electrode 10, a non-silicone adhesive is more suitable than a silicone-based adhesive.

In this way, if the adhesive suitable for bonding the case 20 is different from the adhesive suitable for bonding the electrode 10, the two can be firmly bonded by sandwiching a flexible, planar substrate (e.g., a film, tape, sheet, thin film, etc.) between the case and the electrode, and applying appropriate adhesives to the electrode side of the substrate and the case side of the substrate, respectively.

For example, many commercially available single-sided adhesive tapes are coated with acrylic or urethane adhesives, and by applying a different adhesive to the non-adhesive side of the tape, it is possible to simply and easily bond the case and electrode using a different type of adhesive.

6 shows an enlarged view of the joint between the electrode 10 and the case 20. For ease of understanding, the components are shown partially separated.
For example, when using a silicone case 20 and a graphite sheet electrode 10, one can use single-sided adhesive tape 52 as adhesive member 50, affix the adhesive tape 52 to the electrode 10 side, and then apply a silicone-based adhesive 56 to the non-adhesive side of the adhesive tape or to the case side to bond the case side. In this specification, the adhesive on the adhesive surface of the adhesive tape is called an adhesive, but adhesion and adhesion are synonymous.

An example of adhesive tape 52 is polyester film coated with an acrylic adhesive 54. Graphite sheets have good adhesion even with non-silicone adhesives, and can be easily adhered using adhesive tape 52. The same is true for CNT sheets and conductive polymer sheets. Note that, in cases where a silicone adhesive is applied to the adhesive surface of the adhesive tape, the opposite of the above example can be achieved by attaching the adhesive tape to the case side and then applying a highly versatile acrylic adhesive, for example, to the non-adhesive side of the adhesive tape to adhere the graphite sheet side.

Furthermore, if a highly water-repellent rubber such as silicone is used for the case 20, it is advisable to subject the adhesive side surface of the case 20 to surface treatment such as ozone treatment, plasma treatment, corona treatment, or flame treatment to make it hydrophilic. Ozone treatment is the most suitable hydrophilization treatment because it requires simple equipment and no special raw materials, making it the easiest and most cost-effective method.

In this way, by performing a surface treatment such as ozone treatment on the adhesive surface of the silicone to make it hydrophilic, the adhesion between the case surface and the adhesive can be further improved. If a common adhesive is suitable for both the case 20 and the electrode 10, a single type of adhesive may be applied to one or both of the case 20 and the electrode 10 for adhesion, or double-sided adhesive tape may be used for simplicity. In other words, if a rubber material other than silicone is used as the material for the case 20, a non-silicone adhesive or double-sided adhesive tape may be used as the adhesive member 50 between the electrode 10 and the case 20. The surface treatment may also be applied to other rubber materials, but not applying it does not particularly contribute to improved adhesion.

(Method for manufacturing thermochemical battery)
Next, a method for manufacturing a power-generating thermochemical battery will be described with reference to Figures 4 and 5. In this embodiment, a graphite sheet is used as the electrode 10, and the case 20 is made of silicone.
First, two graphite sheets (of the same size and thickness) and a predetermined amount of electrolyte 30 containing a redox couple are prepared. Next, the case (frame material) 20 is made, but the order of these steps does not matter. The case 20 can be made by pouring silicone raw material into a mold, heating it to harden it, and then cutting it. Specifically, the method is as follows.

First, the base agent (silicone oil) and curing agent (cross-coupling agent) are mixed in the desired ratio (a range of 1:1 to 100:1 is possible) and stirred for a set time (e.g., about 1 hour) at a constant temperature (e.g., about 25°C). The mixing ratio of the base agent and curing agent can be selected appropriately to achieve the desired flexibility. After that, a vacuum is applied for a set time (e.g., about 1 hour) at a constant pressure (e.g., about 50,000 Pa) and a constant temperature (e.g., about 25°C) to remove air bubbles. The mixture is then placed in a mold and solidified by a cross-coupling reaction at a constant temperature (e.g., about 70°C) for a set time (e.g., about 12 hours). Using a non-static container, such as an anti-static plastic container, as the mold is preferable, as this facilitates peeling of the silicone after molding. The center of the case 20 is then cut to form a cylindrical shape. The smaller the cylindrical diameter, the greater the flexibility and the larger the amount of electrolyte that can be contained, so the larger the cut size is. However, an appropriate size can be selected depending on the material, taking into consideration strength, the temperature difference between the upper and lower electrodes, and ensuring a certain degree of adhesive surface area with the electrodes.

The overall size of case 20 is set to be the same as, slightly smaller than, or slightly larger than graphite sheet electrode 10. Specifically, the size should be such that the end of graphite sheet electrode 10 contacts the upper or lower end of case 20.
In the illustrated example, case 20 is arranged along the edge of electrode 10, but it may be arranged at the end (closer to the end than the center) of electrode 10. Note that arranging case 20 at the edge of graphite sheet electrode 10 is preferable because it allows for a wide contact surface between electrolyte 30 and electrode 10.

Then, the graphite sheet electrode 10, which will form the bottom of the thermochemical battery, is adhered to the bottom of the case 20. This adhesion is performed as follows. Prior to this adhesion, it is advisable to perform a surface treatment such as ozone treatment on the adhesion side surface of the case 20.

First, a single-sided adhesive tape 52 (e.g., an acrylic adhesive 54) is attached to the edge of the graphite sheet electrode 10, a silicone adhesive 56 is applied to the surface opposite the adhesive surface of the adhesive tape, and the bottom end of the case (silicone) 20 is placed on the applied surface and pressed to adhere. This seals the bottom end of the opening of the case 20. The silicone adhesive 56 may also be applied to the case 20. The graphite sheet electrode 10 and the case 20 may be bonded together first using the adhesive tape 52. The silicone adhesive 56 may be applied to the case 20 first, and then the adhesive tape 52 may be attached to the graphite sheet electrode 10. The adhesive 56 may be applied by spraying, for example. This also applies to the other embodiments.
Then, once the adhesive 56 has hardened, the electrolyte 30 is poured in so as to avoid the presence of air bubbles.

Furthermore, the graphite sheet electrode 10 is attached to the adhesive surface of the adhesive tape 52, and after silicone-based adhesive 56 is applied to the entire upper end of the case 20, the surface opposite the adhesive surface of the adhesive tape 52 is pressed against the applied surface and the lid is closed. In this way, the sealed body consisting of the case 20 and electrode 10 is filled with electrolyte 30 and sealed liquid-tight. Alternatively, the graphite sheet electrode 10 may be attached after adhesive tape 52 is attached to the case side with silicone-based adhesive 56.

Furthermore, if the same adhesive is used for the electrode 10 and the case 20, they may be attached using double-sided adhesive tape, or adhesive may be applied to one or both of the electrode 10 and case 20 sides to bond them together. Then, by connecting external connection electrodes 40 to the edges of the upper and lower electrodes 10 using a conductive adhesive (not shown), and connecting a device to the external connection electrodes 40, an electrical circuit can be formed.

Furthermore, by installing a separator (ion-permeable membrane) 34 that separates the electrolyte in the thermochemical battery, it can also be used as the rechargeable type (Figure 7). The separator 34 can be any flexible ion-permeable membrane, and an appropriate ion-permeable membrane can be selected depending on the type of electrolyte 30 used. In this case, the ion-permeable membrane must be placed inside the case 21, but this can be easily done by creating two cases 21a and 21b of equal size and sandwiching the ion-permeable membrane between them.

The case can be made in the same way as for a power-generating thermochemical battery. Two identical cases can be made using this method, or one larger case can be cut horizontally into two. It is not a problem if the thickness (height) or size of the two cases differs slightly.

An electrode (e.g., a graphite sheet) 10 is then attached to the bottom of one case 21a to seal the bottom, electrolyte 30a is poured in, and an ion-permeable membrane 34 is attached to the top of the case to seal the lid. The other case 21b is then attached on top of the ion-permeable membrane 34, electrolyte 30b is poured in, and an electrode 10 is attached to the top of the case to seal the lid. The bonding method can be the same as for the power-generating thermochemical battery 5.

If the case 21 is made of silicone, it is recommended to use a silicone adhesive as the adhesive between the cases 21a and 21b and the ion-permeable membrane 34. That is, in this case, the ion-permeable membrane 34 is attached to the adhesive surface of the adhesive tape 52, and the silicone-based adhesive 56 is applied to the entire surface of the cases 21a and 21b, and the surface of the adhesive tape 52 opposite the adhesive surface is pressed against the applied surface.

An example of a combination of the electrolytes 30a and 30b is a potassium chloride solution (or potassium nitrate solution) and a mixed solution of potassium ferrocyanide and potassium ferricyanide. In this case, the ion-permeable membrane 34 is a cation-permeable membrane (the common ion is K ⁺ ). The cation-permeable membrane and the anion-permeable membrane can be selected appropriately depending on the types of electrolytes in the upper and lower electrolytes. For example, if the combination is a potassium chloride solution and a mixed solution of iron (II) chloride and iron (III) chloride, the resulting membrane is an anion-permeable membrane (the common ion is Cl ⁻ ). As long as the common ion of the electrolytes 30a and 30b is the same, the same ion-permeable membrane can be used regardless of the material of the case 21.

(operation)
Next, the operation of the flexible thermochemical battery will be described.
First, the operation of the power generating flexible thermochemical battery 5 will be described.
A power-generating flexible thermochemical battery 5 is placed on a heat source, such as a hot drain pipe or a hot exhaust pipe. In this case, the lower electrode 10 is at a high temperature, and the upper electrode 10 is at a low temperature. As described above, ions in the electrolyte 30 react at the lower electrode 10 on the high-temperature side, becoming ions with a changed valence and electrons, while on the low-temperature side, an influx of electrons causes ions to return to their original valence. Therefore, heat flows from bottom to top in the direction of arrow F (FIG. 5), and current flows in the direction of arrow D. In this way, the battery can be used as a device battery.

Next, the operation of the rechargeable flexible thermochemical battery 6 will be described.
In the case of a rechargeable flexible thermochemical battery 6, when it is kept in a heat source, for example, a warm room, the entire battery heats up ( FIG. 3A ), causing reactions in the electrolyte and on the electrode surfaces in both the upper and lower parts. In the illustrated example, ions (e.g., cations) in the electrolyte 30a generated by a preferential reaction flow in the direction of arrow F ( FIG. 7 ) from the lower side to the upper electrolyte 30b, and current flows in the direction of arrow D, generating electricity until the ions are saturated. If the thermochemical battery 6 is then placed at a different temperature, for example, outdoors in the cold, the opposite reaction occurs, causing the current to flow in the opposite direction, and electricity is generated again until the ions are saturated.

In the case of the charging type, even if there is a temperature difference between the upper and lower electrodes, the influence of the temperature difference can be ignored because the types of electrolytes 30a and 30b inside are different, and the behavior is different from that of the power generation type. Note that the direction of current when the temperature changes will differ depending on the type of electrolyte used in the upper and lower electrodes.
Furthermore, in the case of a rechargeable thermochemical battery, two cases 21a and 21b are stacked on top of each other, so the thickness is slightly increased compared to a power generating thermochemical battery, but this does not affect flexibility in any way.

As described above, the flexible thermochemical batteries 5 and 6 according to this embodiment can be used as the power generation type and the charging type, and therefore, if there is a heat source, the heat can be converted into electricity and stored, and therefore they are expected to be one of the means for recovering surrounding waste heat.
Therefore, the flexible thermochemical batteries 5 and 6 according to this embodiment are capable of both continuous power generation and repeated use, and can be used in a variety of locations.

The flexible thermochemical batteries 5 and 6 according to this embodiment are useful in a variety of devices requiring flexibility. For example, they can be used as power sources for small devices and wearable devices such as mobile phones, audio recording and playback devices, wristwatches, video and still image cameras, temperature and humidity sensors, and body-attachable devices, as well as for animal management devices (GPS (Positioning System) and body temperature management sensors) and plant management devices (temperature and humidity sensors and sunlight sensors). The same applies to other embodiments. Potential heat sources include factory exhaust heat, equipment exhaust heat, exhaust pipes, drainage pipes, household exhaust heat, the human body, animals, geothermal heat, solar heat, and other sources.

In this embodiment, the sealed body consisting of the cases 20, 21 and the electrodes 10 itself forms the outer shape of the thermochemical battery, but other components such as a flexible cover may be added to the outside of the cases 20, 21 and the electrodes 10. If the cover overlaps the electrodes 10, it is recommended to use a thermally conductive material (e.g., a metal thin film, a thermally conductive polymer, etc.). In this case, too, the entire thermochemical battery is flexible, making it applicable to a variety of locations.

Furthermore, while it is preferable that all components constituting a flexible thermochemical battery be flexible, this does not exclude components that include even a small amount of non-flexible parts. This also applies to other embodiments.

(Embodiment 2)
In this embodiment, a plurality of thermochemical cells are electrically connected in series to form a thermochemical cell module.
The voltage can be increased by electrically connecting multiple flexible thermochemical batteries of the power generation type shown in Embodiment 1 in series. In this case, the heat source is located on one end side of each pair of electrodes, so the heat flow is limited to one direction.

FIG. 8A shows a plan view of a thermochemical battery module 60 in which two thermochemical batteries 5 are connected, and FIG. 8B shows a side view (partial cross section) of FIG. 8A.
As shown in these figures, two thermochemical batteries 5 are electrically connected by connecting the external connection electrodes 40 of adjacent thermochemical batteries with a conductive member 70. The conductive member 70 connects the external connection electrode 40 of the low-temperature side (or high-temperature side) electrode 10 of one of the adjacent thermochemical batteries to the external connection electrode 40 of the high-temperature side (or low-temperature side) electrode 10 of the other thermochemical battery, and is disposed between the side walls of the cases 20 of the adjacent thermochemical batteries 5.

The conductive member 70 for connecting the external connection electrode 40 may be any conductive material that does not impair the flexibility of the connection portion. Furthermore, the conductive member 70 is preferably flexible and conductive, but is not particularly limited and may be the same as the external connection electrode 40. For example, metal wire or fiber impregnated with a conductive polymer may be used. This also applies to other embodiments.

(Method for manufacturing a thermochemical battery module)
Next, a method for manufacturing a thermochemical battery module will be described with reference to FIG.
First, two thermochemical batteries 5 are fabricated in the same manner as in Embodiment 1. Then, a linear conductive member 70 is prepared to electrically connect the two thermochemical batteries, and both ends of the conductive member 70 are connected to the external connection electrodes 40 using a conductive adhesive. This connection is not limited to the use of a conductive adhesive, and metal wires or fibers may be directly connected to each other, or other metal wires or conductive polymer-impregnated fibers may be used.
The conductive adhesive may contain graphene, graphite particles, carbon nanotubes, etc. Even if no conductive adhesive is used, an aggregate of graphene, graphite particles, carbon nanotubes, etc. may be applied to the connection portion between the metal wire or conductive polymer-impregnated fiber and the external connection electrode 40.
In order to increase the strength of the conductive member 70, a protective cover may be provided around the conductive member 70.

In this way, by directly connecting a plurality of external connection electrodes 40 of the thermochemical batteries 5, it is possible to easily fabricate a thermochemical battery module 60. On the other hand, a thermochemical battery without external connection electrodes 40 may be fabricated, and the edges of the upper and lower electrodes 10 may be connected only by the conductive member 70.
In addition, by using a sealing material (not shown) on the opposing surfaces of the cases 20 of adjacent thermochemical batteries 5 and around the conductive member 70, the conductive member 70 can be protected and the gap between the side walls can be filled.

(operation)
The flow of current in the thermochemical battery module 60 will now be described.
When the thermochemical battery module 60 is placed on a heat source (for example, a hot drain pipe or a hot exhaust pipe), the electrode 10 on the ground side (hereinafter referred to as the lower side) becomes hot, and the electrode 10 on the opposite side to the ground side (hereinafter referred to as the upper side) becomes cold. Therefore, in both of the two thermochemical batteries 5 constituting the module, the lower electrode 10 becomes hot and the upper electrode 10 becomes cold, and heat flows from the lower side to the upper side in the direction of arrow F, and current flows from the upper electrode 10 in the direction of arrow D via the conductive member 70 to the lower electrode 10 of the adjacent thermochemical battery 5.

This current causes a linear current to flow (in the direction of arrow D) between the two thermochemical batteries 5. A DC circuit is formed by connecting a device to the external connection electrodes 40 on one end and the other end of the series-connected thermochemical batteries 5. The external connection electrode 40 is connected to the lower electrode 10, which is at a high temperature, on the input side of the battery, and to the upper electrode 10, which is at a low temperature, on the output side.

In this way, with the thermochemical battery module 60 of this embodiment, multiple thermochemical batteries 5 are connected, allowing stable, high-power generation from a wide area of a low-temperature heat source. This is also true for the thermochemical battery modules of other embodiments.

Although this embodiment shows an example in which two thermochemical batteries are connected, more than two thermochemical batteries may be connected. Furthermore, the invention is not limited to connecting identical thermochemical batteries, but may also connect thermochemical batteries of different shapes and sizes. Furthermore, the invention is not limited to connecting batteries in a straight line, but can also be connected in a bent shape, making it possible to accommodate any shape or size to fit the shape of the installation surface. It is also applicable to rechargeable thermochemical batteries.
(Embodiment 3)

Fig. 9(A) shows a plan view of a thermochemical battery module in which two thermochemical batteries are connected, and Fig. 9(B) shows a side view (partial cross section) of Fig. 9(A). For ease of understanding, the conductive member inside the case side wall is shown as a cross section. This is also true for other embodiments.
The thermochemical battery module 62 of this embodiment is similar to the thermochemical battery module of embodiment 2 in that it is a thermochemical battery module in which two thermochemical batteries 7 are connected, but differs from the thermochemical battery module of embodiment 2 in that the side walls of the adjacent cases of the two thermochemical batteries are common.

In other words, while the thermochemical battery module 60 of embodiment 2 is configured by connecting two independent thermochemical batteries 5 in series, in this embodiment the cases of the two thermochemical batteries are unitized to obtain the same amount of power as the thermochemical battery module of embodiment 2. Furthermore, instead of connecting the external connection electrodes of the thermochemical batteries using a conductive member, a pair of upper and lower electrodes are connected.

The conductive member 72 connects the low-temperature (or high-temperature) electrode 12a of one adjacent thermochemical battery 7 to the high-temperature (or low-temperature) electrode 12a of the other adjacent thermochemical battery 7.

In the illustrated example, the pair of upper and lower electrodes 12 (12a, 12b) of the thermochemical battery are approximately the same size, but to ensure space for the connecting portion 12aa of the conductive member 72 (hereinafter referred to as the conductive connection portion), it is preferable to make the sizes slightly different so that this portion is wider. That is, as shown in Figure 9, of the pair of upper and lower electrodes 12, the length of the side in the current direction (direction of arrow D) of electrode 12a having the conductive connection portion 12aa is longer than that of electrode 12b without the conductive connection portion.

(Method for manufacturing a thermochemical battery module)
Next, a method for manufacturing a thermochemical battery module 62 will be described with reference to FIG. 9 . Similar to the first embodiment, a case will be described in which graphite sheets are used as the electrodes 12 and the case 22 is made of silicone. Basically, the method is the same as the second embodiment, but two larger electrodes 12a and two smaller electrodes 12b are prepared as graphite sheets (electrodes). For example, the short sides may be the same length but the long sides may be different. The electrolyte containing the redox couple may be the same as that in the first embodiment.

Then, one or more, preferably multiple, linear conductive members 72 are prepared as needed to electrically connect the thermochemical batteries 7. These conductive members 72 may be similar to the conductive members 70 of embodiment 2 and may be of the same length. The conductive members 72 may be connected to the thermochemical batteries using the same material as that used to connect the conductive members 70 of embodiment 2 to the external connection electrodes 40. The number and size of the conductive members 72 are not particularly limited, but should be an appropriate number and size so as to maintain the strength of the side walls of the case 22 (the partitions described below) and to provide an appropriate spacing, taking workability into consideration. This also applies to the thermochemical battery modules of other embodiments.

The case (frame material) 22 can be made in essentially the same way as the case of embodiment 1, by changing the size and shape of the silicone molding mold. In this case, the solidified material after molding is cut in two places longitudinally, forming a part whose interior is divided into two compartments 22b by a partition 22a.

Then, an electrode (graphite sheet) 12 that will form the bottom of the thermochemical battery 7 is adhered to the bottom of the case 22. At this time, electrodes 12a and 12b of different sizes are aligned and adhered to the case. The adhesion method may be the same as in embodiment 1. Then, electrolyte 30 is poured into each of the two compartments 22b separated by the partition 22a inside the case 22. After that, an electrode 12 is attached to the top of the case 22, the lid is closed, and the electrodes are pressed and adhered. At this time, in the compartment with the smaller electrode 12b attached to the bottom, a larger electrode 12a is attached above it, and in the compartment with the larger electrode 12a attached to the bottom, a smaller electrode 12b is attached above it. In other words, the larger electrodes 12a and the smaller electrodes 12b are arranged above and below the compartments 22b so that they are staggered vertically. By arranging them in this manner, the conductive connection portion 12aa of the upper (or lower) electrode 12a of one adjacent compartment 22b and the conductive connection portion 12aa and partition portion 22a of the lower (or upper) electrode 12a of the other adjacent compartment 22b overlap in plan view.

Next, holes (not shown) for inserting the conductive members 72 are formed in the partition 22a of the case 22 and the upper and lower electrodes 12a, the number of which corresponds to the number of conductive members. The conductive members 72 are then inserted into the holes to connect the upper and lower electrodes 12a. If necessary, they may be fixed in place with adhesive. Note that since the electrolyte 30 is sealed in the partition 22a of the case 22 (the portion in contact with the graphite sheet), placing the conductive members 72 inside the partition 22a does not affect the sealing effect.

Then, as in embodiment 1, the external connection electrode 40 is connected to the edge of the smaller electrode 12b of each thermochemical battery 7. It does not matter whether the external connection electrode 40 or the conductive member 72 is connected first. This also applies to thermochemical battery modules of other embodiments. The shape of the case 22 and the shapes of the compartments 22b are not particularly limited and may be circular, other polygonal shapes, or shapes including curves and straight lines. The shape and size of the electrodes 12 are not particularly limited to this embodiment as long as the conductive connection portions 12aa of the upper and lower electrodes of adjacent compartments 22b overlap or are adjacent in plan view. This also applies to thermochemical battery modules of other embodiments that have conductive connection portions.

(operation)
The current flow in the thermochemical battery module 62 is the same as in the second embodiment, and when the thermochemical battery module 62 is placed on a heat source (for example, a hot drain pipe or a hot exhaust pipe), the lower electrodes 12 of the two thermochemical batteries constituting the module are both at high temperature and the upper electrodes 12 are at low temperature, and heat flows from the bottom to the top in the direction of arrow F. Accordingly, current flows in the direction of arrow D from the upper electrode 12 a to the lower electrode 12 a via the conductive member 72.

This current causes a linear current to flow (in the direction of arrow D) between the two thermochemical cells 7. A DC circuit is formed by connecting a device to the external connection electrodes 40 on one and the other ends of the series-connected thermochemical cells 7. The external connection electrode 40 is connected on the input side of the battery to the lower electrode 12b, which is at a high temperature, and on the output side to the upper electrode 12b, which is at a low temperature.

As such, in the thermochemical battery module 62 of this embodiment, between adjacent thermochemical batteries 7, the upper electrode 12a of one thermochemical battery partially overlaps the lower electrode 12a of the other thermochemical battery in a plan view, i.e., when viewed perpendicular to the electrode surface. By placing a conductive member 72 between the overlapping upper and lower electrodes 12a, the conductive member 72 can be easily connected and has excellent strength. Furthermore, since there are no gaps between adjacent thermochemical batteries, the module is compact and high-power.

Furthermore, the conductive member 72 is fixed and protected by being placed within the partition portion 22a, which is the side wall of the case 22. Therefore, when the thermochemical battery module is bent, the conductive member 72 bends along with the case 22, making it highly impact-resistant and durable. Furthermore, since the adjacent side walls of the case 22 are shared between adjacent flexible thermochemical batteries, a larger amount of electrolyte can be used and the electrode surface area can be increased, allowing for high power output without increasing the size. Furthermore, the entire thermochemical battery module 62 has a simple and compact structure, which also leads to weight and cost savings. Furthermore, since multiple thermochemical batteries can be manufactured simultaneously as an integrated unit, the effort required to manufacture and connect independent thermochemical batteries is reduced, resulting in excellent workability.

While this embodiment illustrates an example in which two thermochemical batteries are unitized, more than one thermochemical battery may be unitized. Furthermore, the batteries are not limited to being linearly elongated, but can also be bent. This allows for a variety of shapes and sizes to be accommodated to the shape of the installation surface. Connecting more thermochemical batteries increases the likelihood of gaps forming at the connections, resulting in increased area loss. However, this embodiment shares a common sidewall on the adjacent sides of the thermochemical batteries, improving output density (output per unit area) compared to the second embodiment. This embodiment can also be used in rechargeable thermochemical batteries. While this embodiment illustrates a case in which the conductive connections 12aa of the upper and lower electrodes 12a overlap in a planar view, even if the conductive connections 12aa of the upper and lower electrodes 12a do not overlap in a planar view, the length of the conductive member 72 can be adjusted to position the conductive member 72 within the partition 22a and connect the upper and lower electrodes 12a.

(Embodiment 4)
Furthermore, as an example of electrically connecting a plurality of independent thermochemical cells, it is also possible to connect them without using external connection electrodes.
FIG. 10(A) shows a plan view of a thermochemical battery module in which two thermochemical batteries are connected, and FIG. 10(B) shows a side view of FIG. 10(A).
The thermochemical battery module 64 of this embodiment is similar to the thermochemical battery module 60 of embodiment 2 in that it is configured by connecting two independent thermochemical batteries 8 in series, but differs in that adjacent upper and lower electrodes 14a are connected directly without using external connection electrodes 40.

The upper and lower electrodes 14a are connected by a conductive member 74, and the upper (or lower) electrode 14a of one of the adjacent thermochemical cells 8 is arranged so as to partially overlap the lower (or upper) electrode 14a of the other thermochemical cell in plan view, which is common to the thermochemical cell module 62 of the third embodiment. That is, the larger electrodes 14a and the smaller electrodes 14b are arranged alternately above and below the case 20. The conductive member 74 and the thermochemical cells may be connected using the same material as that used to connect the conductive member 70 and the external connection electrode 40 of the second embodiment.
Furthermore, a protective cover may be provided to increase the strength of the conductive member 74, or a sealant may be used on the opposing surfaces of the cases of adjacent thermochemical batteries 8 or around the conductive member 74 to fill the gap between the side walls. This embodiment also achieves the same effects as those of embodiments 2 and 3. It can also be applied to a rechargeable thermochemical battery.

(Embodiment 5)
This embodiment, like the thermochemical battery module of embodiment 3, has a common side wall between adjacent cases of thermochemical batteries, but differs from the thermochemical battery module of embodiment 3 in that it is a thermochemical battery module in which four thermochemical batteries are connected.

Figure 11 shows a plan view of the flexible thermochemical battery module of this embodiment (Figure 11(A)) and a plan view of the case (Figure 11(B)), and Figure 12 shows a side view of the flexible thermochemical battery as viewed from each direction (arrows A-C) in Figure 11(A).
As shown in these figures, four thermochemical batteries 9 are electrically connected in series by conductive members 76. The conductive members 76 connect the low-temperature (or high-temperature) electrode 16 of one adjacent thermochemical battery 9 to the high-temperature (or low-temperature) electrode 16 of the other thermochemical battery 9. The conductive members 76 may be connected to the thermochemical batteries using the same material as that used to connect the conductive members 70 and the external connection electrodes 40 in the second embodiment. The pair of upper and lower electrodes 16 of each thermochemical battery 9 are approximately the same size, but may be elongated horizontally to ensure sufficient space for the conductive connection portions 16a. The pair of upper and lower electrodes 16 are arranged in each compartment 24b of the case 24 so that the long side corresponds to the direction of current (the direction indicated by arrow D, the direction of current flow through the conductive connection portions 16a).

(Method for manufacturing a thermochemical battery module)
Next, a method for manufacturing a thermochemical battery module 66 will be described with reference to FIGS. 11 and 12 . Similar to the third embodiment, a case in which graphite sheets are used as the electrodes 16 and the case is made of silicone will be described. Basically, the method is the same as the third embodiment, but eight rectangular graphite sheets of the same size (four on each side) are prepared. The conductive connectors 16 a connecting the upper and lower electrodes 16 can be provided on the long side edges of the rectangles. Making the graphite sheets the same size improves the workability and productivity of the thermochemical battery. Alternatively, as in the third embodiment, two types of graphite sheets of different sizes (e.g., sheets with the same short side length but different long side lengths) may be prepared, each with four sheets.

In other words, there are no particular limitations on the shape or size of the conductive member 76, as long as it can secure installation space for the conductive member 76 and can cover the openings of each compartment 24b of the case 24. This also applies to other thermochemical battery modules that have conductive connections. Furthermore, the electrolyte containing the redox couple may be the same as in embodiment 1.

Then, one or more, preferably multiple, linear conductive members 76 are prepared as needed to electrically connect the thermochemical cells 9. These conductive members 76 may be similar to the conductive members 70 of embodiment 2 and may be of the same length. In this embodiment, since four thermochemical cells are connected, conductive members 76 must be placed at three connection points (conductive connection portions 16a). The size and number of these conductive members 76 can be considered the same as for the conductive members of embodiment 3.

Next, the case (frame material) 24 is made in the same manner as the case of embodiment 1, except for changing the size and shape of the silicone molding mold. In this case, the solidified material after molding is cut in four places on the left and right, forming a case whose interior is divided into four compartments 24b by partitions 24a.

Then, an electrode (graphite sheet) 16 that will form the bottom of the thermochemical battery 9 is adhered to the bottom of the case 24, with the graphite sheet arranged so that the short and long sides of the rectangle in adjacent sections 24b are oriented in a staggered pattern.

The bonding method may be the same as in embodiment 1. Then, electrolyte 30 is poured into each of the four compartments separated by partitions 24a inside the case 24. After that, electrodes 16 are attached to the top of the case 24, the lids are closed, and the case is pressed and bonded. At this time, the upper and lower electrodes 16 are arranged so that their vertical and horizontal orientations are staggered. By arranging them in this manner, the conductive connection portion 16a of the upper (or lower) electrode 16 of one adjacent compartment 24b and the conductive connection portion 16a and partition 24a of the lower (or upper) electrode 16 of the other compartment 24b overlap in a planar view.

Next, holes (not shown) for inserting the conductive members 76 are formed in the partition 24a of the case 24 and the upper and lower electrodes 16, the number of which corresponds to the number of conductive members, and the conductive members 76 are inserted into the holes to connect the upper and lower electrodes 16. This connection is the same as in embodiment 3, so a description thereof will be omitted. This operation is performed in each compartment 24b. Then, external connection electrodes 40 are connected to the input and output electrodes 16 of the thermochemical battery module 66, as in embodiment 1. The shapes of the case 24 and the compartments 24b are not particularly limited and may be circular, other polygonal shapes, or shapes including curves and straight lines.

(operation)
The current flow in the thermochemical battery module 66 is the same as in Embodiments 2-4, but when the thermochemical battery module is placed on a heat source (for example, a hot drain pipe or a hot exhaust pipe), the lower electrodes 16 of all four thermochemical batteries 9 constituting the module become hot and the upper electrodes 16 become cold, and heat flows from the bottom to the top in the direction of arrow F ( FIG. 12 ). Accordingly, current flows in the direction of arrow D from the upper electrode 16 to the lower electrode 16 via the conductive member 76.

This current causes current to flow between the four thermochemical cells 9 in a U-shape (in the direction of arrow D) when viewed from above (Figure 11). Furthermore, a DC circuit is formed by connecting a device to the external connection electrodes 40 on one and the other ends of the series-connected thermochemical cells 9. The external connection electrode 40 is connected on the input side of the battery to the lower electrode 16, which is at a high temperature, and on the output side to the upper electrode 16, which is at a low temperature.

The thermochemical battery module of this embodiment achieves the same effects as in embodiment 3. While this embodiment shows an example in which four thermochemical batteries 9 are unitized, more than two thermochemical batteries may be unitized and spread two-dimensionally. For example, the thermochemical batteries may be arranged in a 3x3 configuration, stepped or zigzag in plan view, or any shape or size can be accommodated by changing the shape and size of the case to match the shape and size of the installation surface. This can also be applied to rechargeable thermochemical batteries. Even if the conductive connection portions 16a of the upper and lower electrodes 16 do not overlap in plan view, the length of the conductive member 76 may be adjusted to position the conductive member 76 within the partition portion 24a to connect the upper and lower electrodes 16.

Example 1
A thermochemical battery (power generating type) was fabricated in the following manner.
Two graphite sheets (EYGS091210, manufactured by Panasonic Corporation, area 4.5 cm ² , thickness approximately 0.1 mm) were prepared as electrodes 10. Furthermore, potassium ferrocyanide (K ₄ Fe(CN) ₆ ) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and potassium ferricyanide (K ₃ Fe(CN) ₆ ) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were mixed and stirred as electrolyte 30, followed by guanidinium chloride (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) so that the molar concentrations (mol/L) of the compounds were as follows:
Potassium ferrocyanide (K ₄ Fe(CN) ₆ ): potassium ferricyanide (K ₃ Fe(CN) ₆ ): guanidinium chloride (CH ₆ ClN ₃ ) = 0.4 M: 0.4 M: 1.0 M

Next, a silicone rubber case 20 was fabricated using PDMS (polydimethylsiloxane, manufactured by Dow Corning Toray Co., Ltd., SILPOT 184, two-component mixture type) as the raw material. First, the base resin and curing agent were mixed in a 10:1 ratio and stirred for one hour at a temperature of 25°C. A vacuum was then applied for one hour at 50,000 Pa and 25°C. The product was then placed in a rectangular container (ABS non-charged rectangular case, type 10, external dimensions 194 mm x 104 mm x 26 mm, manufactured by AS ONE Corporation) and allowed to stand at 70°C for 12 hours to solidify.

The solidified material was then removed from the container and cut to the specified size (30 mm x 60 mm), after which the center was cut off to create a rectangular cylindrical case. Furthermore, both end surfaces of the case were subjected to a surface treatment with ozone in air at room temperature using a surface modification device (ASM401N, manufactured by Asumi Giken Co., Ltd.).

An adhesive tape with an acrylic adhesive (Scotch (registered trademark), VHB (registered trademark) acrylic foam structural bonding tape, Y-4920, manufactured by 3M Corporation) was then attached to the edge of the graphite sheet, and a silicone adhesive (MPX-1, manufactured by Konishi Co., Ltd.) was applied to the surface of the adhesive tape opposite the adhesive, and the underside (the surface that would become the bottom) of the case was adhered to it.
Next, the case was filled with the prepared electrolyte, and the top of the case was covered with a graphite sheet using silicone adhesive and adhesive tape, in the same manner as in the previous method.

The overall size of the thermochemical battery produced was 30 mm x 60 mm, with a thickness of approximately 4 mm (electrolyte part dimensions: 15 mm x 30 mm, thickness 3.5 mm).

Figure 13 shows a photograph of the thermochemical battery when bent. As shown, the flexible thermochemical battery of this example can be easily bent with fingers, and even when kept in this state for more than a month, no leakage of electrolyte was observed. Therefore, the flexible thermochemical battery can be used not only on flat surfaces with curved or uneven surfaces, but also by wrapping it around a person's arm, a pipe, etc.

Example 2
Thermochemical batteries (power generation type) were fabricated using natural rubber (GS-09, manufactured by Wake Sangyo Co., Ltd.) and special synthetic rubber (non-silicone type) (KGS-021, environmentally friendly rubber, manufactured by Wake Sangyo Co., Ltd.) as the materials for the case 20. Conditions other than the material of the case 20, i.e., the type of electrodes and the composition of the electrolyte, were the same as in Example 1. Square cylindrical cases were fabricated by cutting the center of commercially available sheets of natural rubber and special synthetic rubber. The graphite sheet was cut to fit the size of each case. The size of the natural rubber case was 50 mm x 50 mm, and the size of the special synthetic rubber case was 30 mm x 40 mm.

Thermochemical batteries were fabricated in the same manner as in Example 1, except that the adhesive surface of the case 20 was not surface-treated and double-sided adhesive tape (3M Corporation, Scotch®, KPS-100, acrylic adhesive) was used to attach the electrode 10 to the case 20. The dimensions of the fabricated thermochemical batteries were 50 mm x 50 mm and approximately 4 mm thick (electrolyte dimensions: 30 mm x 30 mm, 3.5 mm thick) for the natural rubber battery and 30 mm x 40 mm and approximately 4 mm thick (electrolyte dimensions: 10 mm x 20 mm, 3.5 mm thick) for the special synthetic rubber battery. The amount of electrolyte was adjusted to meet the respective electrolyte dimensions. Both thermochemical batteries were flexible, and no electrolyte leakage was observed with slight bending. However, when bent to the same extent as the thermochemical battery with the silicone case of Example 1 (Figure 13), electrolyte leakage and cracks were observed. Therefore, it can be said that the thermochemical battery with the silicone case of Example 1 has better flexibility.

14 shows the measurement results of the output characteristics of the thermochemical batteries of Examples 1 and 2. The horizontal axis represents voltage (mV), and the vertical axis represents output density (μW/cm ² ). The black circles represent the results for the thermochemical battery with a silicone case of Example 1, the black triangles represent the results for the thermochemical battery with a natural rubber case of Example 2, and the squares represent the results for the thermochemical battery with a special synthetic rubber case of Example 2.

A hot plate was used as a heat source, with the high-temperature side temperature set to 28°C and the low-temperature side allowed to cool naturally (room temperature 25°C). The output was measured by directly contacting the electrodes 10 of the thermochemical battery with external conductive wires 2 (FIG. 1) connected to a measuring instrument (Keithley Instruments, Inc., SourceMeter® 2400). No external resistor was used. The measurement time was 1 minute.
As shown in Figure 14, it was confirmed that an output of approximately 0.25 to 1.6 μW/ ^cm² could be obtained even with a temperature difference of only 3°C. With this level of output, several units could be connected together and used as a power source for a temperature and humidity sensor using a boost circuit.

These results also showed that the output per unit area was overwhelmingly greater for thermochemical batteries with silicone cases. This is thought to be because silicone has a fairly low thermal conductivity, making it difficult for heat to be transferred from the lower electrode on the grounded side of the heat source to the upper electrode, maintaining a temperature difference between the upper and lower electrodes. In the case of thermochemical batteries with natural rubber cases and special synthetic rubber cases, it is thought that a temperature difference between the upper and lower electrodes was less likely to occur, resulting in lower output than would be the case if it were due to an actual temperature difference. Therefore, it can be said that thermochemical batteries with silicone cases are excellent in terms of output characteristics as well.

Example 3
A thermochemical battery (rechargeable type) was fabricated in the following manner.
A cation exchange membrane (CIMS, manufactured by Astom Corporation) was used as the separation material 34 (FIG. 7), the composition of the electrolyte 30a was a mixed solution of potassium ferrocyanide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and potassium ferricyanide (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and was adjusted to satisfy the following conditions, and the composition of the electrolyte 30b was a potassium chloride solution (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.).
Composition of the electrolyte 30a: potassium ferrocyanide (K ₄ Fe(CN) ₆ ): potassium ferricyanide (K ₃ Fe(CN) ₆ ): guanidinium chloride (CH ₆ ClN ₃ ) = 0.4 M: 0.4 M: 1.0 M
Composition of electrolyte 30b: potassium chloride solution 1.0M
The type of electrode, the material of the case, the adhesive tape, the adhesives, etc. were the same as those in Example 1.

Two rectangular cylindrical cases (outer dimensions: 30 × 70 mm, electrolyte area: 4.0 cm ² , thickness: 3.5 mm) were fabricated as silicone rubber cases 21 in the same manner as in Example 1. Surface treatment was performed on both end surfaces of each of the cases 21 a and 21 b in the same manner as in Example 1.

The graphite sheet and case 21a were then bonded together using acrylic adhesive tape and a silicone adhesive. Electrolyte 30a was poured into case 21a without leaving any voids. A cation exchange membrane was then attached to the top of case 21a in the same manner as above, and the case was then covered. Case 21b was then attached on top of the cation exchange membrane, and electrolyte 30b was poured into case 21b without leaving any voids. The top of case 21b was then covered with a graphite sheet. The overall dimensions of the fabricated thermochemical battery were 30 mm x 70 mm, with a thickness of approximately 8.0 mm (electrolyte portion dimensions: area 4.0 ^cm2 , thickness 7.0 mm).

The flexible thermochemical battery of this example could also be easily bent with fingers, and no leakage of electrolyte was observed even when bent to the same extent as the flexible thermochemical battery of Example 1 (FIG. 13).
15A and 15B show the measurement results of the output characteristics of the thermochemical battery, where Fig. 15A shows the relationship between time and temperature, and Fig. 15B shows the relationship between time and load voltage.
The output was measured by directly contacting the external conductive wires 2 (FIGS. 2 and 3) connected to a measuring instrument (Memory Hilogger LR8400, manufactured by Hioki E.E. Corporation) with the electrodes 10 of the thermochemical battery. The resistance at this time was 40 Ω (ohms).
In addition, the effective area of the graphite sheet relative to the heat source (ground surface) was 4.0 cm ² .
The thermochemical battery was then placed in a temperature environment (temperature-controlled room) of 5° C. and 60° C. at regular intervals (30 minutes) and the load voltage was measured.
These results show that the thermochemical battery can obtain a voltage of approximately 40 mV at high temperatures and 30 mV in the opposite direction at low temperatures. It was also confirmed that the current flows in the opposite direction when the thermochemical battery is in the high-temperature and low-temperature states, which means that the battery can be used repeatedly.

Example 4
A thermochemical battery module was fabricated by unitizing four thermochemical batteries using the following method. The types of electrodes, the composition of the electrolyte, the raw materials for the case, the adhesive tape, and the adhesives were the same as those used in Example 1.
Eight rectangular graphite sheets (area 4.5 cm ² , thickness approximately 0.1 mm) were prepared as electrodes 16. A rectangular container with an outer diameter of 194 mm × 104 mm (same as in Example 1) was used to fabricate a unit case 24 (outer diameter 80 mm × 80 mm, electrolyte portion 20 mm × 22.5 mm, thickness 3.5 mm) in the same manner as in Example 1. The solidified material removed from the container was cut in four places on the left and right to create a unit case divided into 2 × 2 sections. Furthermore, both end surfaces of the case were surface-treated with ozone in the same manner as in Example 1.

Then, four graphite sheets were attached to the underside of the case using adhesive tape and silicone adhesive. They were arranged in alternating vertical and horizontal orientations, with the long and short sides of adjacent graphite sheets facing in opposite directions.

Next, electrolyte 30 was poured into each of the four compartments 24b in the case, ensuring that no voids were formed, and the top surface of the case 24 for each compartment 24b was covered with four graphite sheets using a method similar to that used in Example 1. At this time, the graphite sheets were arranged vertically and horizontally so that the long and short sides of the upper and lower compartments 24b were oriented in a staggered manner.

Seven holes were then drilled through the case divider 24a and the graphite sheets above and below it. Conductive carbon fibers (Epoch Corporation, carbon roving, G-08-020) 76 were inserted through the holes and sewn to the edges of the upper and lower graphite sheets. This process was repeated three times. The resulting thermochemical battery module measured 80 mm x 80 mm and was approximately 4 mm thick (each electrolyte section dimension: 20 mm x 22.5 mm, thickness: 3.5 mm).

FIG. 16 shows the measurement results of the output characteristics of the thermochemical battery module.
The high-temperature side temperature was 37°C, and the low-temperature side was allowed to cool naturally. The temperature difference was 3°C (34°C when allowed to cool naturally). The effective area for the heat source of four graphite sheets was 18 ^cm2 (4.5 ^cm2 x 4). As in the thermochemical batteries of Examples 1 and 2, a measuring instrument (SourceMeter (registered trademark) 2400, manufactured by Keithley Instruments Inc.) was used for the measurement, and the measurement time was 1 minute.

As shown in Figure 16, it was confirmed that an output of 33 μW was obtained even with a temperature difference of just 3°C. With this level of output, it can be used as a temperature sensor via various boost circuits, and it is also possible to wirelessly transmit temperature information to a mobile device.

The thermochemical battery of the present invention can be used as a power source without charging as long as there is a heat source, making it suitable for use as a power source for mobile devices, etc. Furthermore, because the thermochemical battery of the present invention is lightweight, harmless, inexpensive, and can fit on uneven surfaces, it may also be used as a power source for digital healthcare devices worn on the human body, animal and plant management devices, etc.

1 Electrode 2 Conductive wire 3 Electrolyte 4 Separator 5, 6, 7, 8, 9 Thermochemical cell 10, 12, 14, 16 Electrode 12a, 14a Larger electrode 12b, 14b Smaller electrode 20, 21 Case 22, 24 Case (unit)
22a, 24a Partitions 22b, 24b Compartment 30 Electrolyte (electrolyte solution)
34 Separation material (ion permeable membrane)
40 External connection electrode 50 Adhesive member 52 Adhesive tape 54 Adhesive 56 Adhesive 60, 62, 64, 66 Thermochemical battery module 70, 72, 74, 76 Conductive member D Current direction F Heat flow direction

Claims (16)

A thermochemical battery comprising a pair of electrodes and a pair of aqueous solution electrolytes present between the pair of electrodes in contact with the electrodes and separated by a separator, the thermochemical battery being capable of generating electricity through an oxidation-reduction reaction between the pair of aqueous solution electrolytes and the pair of aqueous solution electrolytes in the vicinity of the surfaces of the pair of electrodes when the pair of aqueous solution electrolytes are under a predetermined temperature condition,
the predetermined temperature condition is a temperature condition in which a state with a heat source and a state without a heat source are alternately maintained;
A flexible thermochemical battery having the aqueous electrolyte therein and comprising a flexible sealing body. A thermochemical battery comprising a pair of electrodes and an aqueous electrolyte present between the pair of electrodes and in contact with the electrodes, the thermochemical battery being capable of generating electricity when there is a temperature gradient difference between the pair of electrodes,
a flexible sealing body having the aqueous electrolyte solution therein;
The sealing body is
The pair of electrodes having flexibility;
a flexible and insulating case disposed between the ends of the pair of flexible electrodes, the case containing the aqueous electrolyte solution therein;
A flexible thermochemical battery comprising: The sealing body is
The pair of electrodes having flexibility;
a flexible and insulating case disposed between the ends of the pair of flexible electrodes, the case containing the aqueous electrolyte solution therein;
10. The flexible thermochemical battery of claim 1, comprising: 4. The flexible thermochemical battery according to claim 2, wherein the pair of flexible electrodes are carbon sheets or conductive polymer sheets. 5. The flexible thermochemical battery according to claim 2 , wherein the flexible and insulating case is made of rubber. The flexible thermochemical battery described in claim 4 or 5, characterized in that a conductive polymer sheet is provided on the electrolyte-side surfaces of the pair of carbon sheet electrodes. 7. The flexible thermochemical battery according to claim 2 , wherein an adhesive member is provided between the electrode and the case to bond the electrode and the case together. The flexible thermochemical battery described in claim 7, characterized in that the adhesive member comprises an adhesive on the electrode side, an adhesive on the case side, and a flexible substrate disposed between the adhesive on the electrode side and the adhesive on the case side. The adhesive member is
an adhesive member having an adhesive on the electrode side, and an adhesive provided between the case and the adhesive member to bond the adhesive member to the case; or
8. The flexible thermochemical battery according to claim 7, further comprising: an adhesive member having an adhesive on the case side; and an adhesive provided between the electrode and the adhesive member, for bonding the adhesive member and the electrode. the flexible and insulating case is made of silicone rubber;
the pair of flexible electrodes are carbon sheets or conductive polymer sheets,
the adhesive or pressure-sensitive adhesive on the electrode side is a non-silicone adhesive;
10. The flexible thermochemical battery according to claim 8, wherein the adhesive or pressure sensitive adhesive on the case side is a silicone adhesive. A flexible thermochemical battery module comprising a plurality of flexible thermochemical batteries according to any one of claims 1 to 10 electrically connected in series. The flexible thermochemical battery module described in claim 11, characterized in that, between adjacent flexible thermochemical batteries connected in series, one of a pair of electrodes of one flexible thermochemical battery partially overlaps with the electrode of the pair of electrodes of the other flexible thermochemical battery opposite the one electrode in a plan view, and a conductive member connecting the one electrode and the opposite electrode is provided at the overlapping location. the sealed body of the flexible thermochemical battery comprises the pair of flexible electrodes, and a flexible and insulating case disposed between ends of the pair of flexible electrodes, the case containing the aqueous electrolyte therein,
In the adjacent flexible thermochemical batteries connected in series, the adjacent side wall of the case of one flexible thermochemical battery also serves as the adjacent side wall of the case of the other flexible thermochemical battery,
The thermochemical battery module according to claim 11 or 12, characterized in that a conductive member is provided within the side wall, connecting one of a pair of electrodes of one flexible thermochemical battery to the opposite electrode of a pair of electrodes of the other flexible thermochemical battery. a flexible and insulating case including a cylindrical outer frame and partition members that divide the interior of the outer frame into a plurality of compartments;
a pair of flexible electrodes that close both ends of an opening of each compartment of the case;
an aqueous electrolyte filled in each compartment and sealed by the case and electrodes;
a conductive member that electrically connects the plurality of compartments in series, the conductive member being provided inside the partition member and connecting an electrode on one end side of an opening of one of the adjacent compartments to an electrode on the other end side of the opening of the other compartment;
A flexible thermochemical battery module capable of generating electricity when there is a temperature gradient difference between the electrode on one end of the opening of each compartment and the electrode on the other end of the opening. a flexible and insulating case including a cylindrical outer frame and partition members that divide the interior of the outer frame into a plurality of compartments;
a pair of flexible electrodes that close both ends of an opening of each compartment of the case;
a pair of aqueous electrolyte solutions filled in each compartment, sealed by the case and the electrodes, and separated by a separator arranged horizontally to the electrode surfaces;
a conductive member that electrically connects the plurality of compartments in series, the conductive member being provided inside the partition member and connecting an electrode on one end side of an opening of one of the adjacent compartments to an electrode on the other end side of the opening of the other compartment;
a flexible thermochemical battery module capable of generating electricity by an oxidation-reduction reaction between the electrolytes of each pair of aqueous solutions in each compartment and the surfaces of each pair of electrodes when the electrolytes are at a predetermined temperature condition,
A flexible thermochemical battery module, wherein the predetermined temperature condition is a temperature condition in which a state with a heat source and a state without a heat source are alternately maintained . The flexible thermochemical battery module described in claim 14 or 15, characterized in that the partition member, the portion to which the conductive member of the electrode on one end of the opening of one compartment is connected, and the portion to which the conductive member of the electrode on the other end of the opening of the other compartment is connected overlap in plan view.