JP3142093B2 - Storage type temperature difference battery - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a novel temperature difference battery which has a normal power generation and storage function when there is a temperature difference between two electrodes and is capable of discharging when the temperature difference has disappeared. The present invention relates to a power storage type temperature difference battery that is effective as a backup power source for low-temperature exhaust heat recovery and cogeneration.

[0002]

2. Description of the Related Art Conventionally, as a thermoelectric converter, a concentration cell using an electrolyte solution in which anions are gasified has been known. FIG. 2 shows an outline of the concentration cell.

[0003] The configuration of the battery, as shown in FIG. 2, the upper and lower glass tube 10 of circular, each gas bridge B ₁ and solution bridge B ₂ 2 one cell C ₁ is connected with, C _2, And graphite fiber intercalation compound 1. In these cells C ₁ and C ₂ , platinum lead wires 2 are inserted to form electrodes. Further, as the graphite fiber intercalation compound 1 is not dispersed to a solution bridge B _2, glass filters 3 are arranged as shown.

The electrolyte 4 contains 10% K saturated with Br _2.
An aqueous solution of Br is used, and the electrolyte is injected from the injection valve 5 so that the lower part of the graphite fiber intercalation compound 1 is filled to the extent that it is immersed. The low temperature medium 6 between the cell C _1, C _2, gives a high-temperature medium 7, cooling the outside of the cell C ₁ and C _2, producing a warmed temperature difference. Then, a difference in concentration of Br ₂ and Br ⁻ occurs between high and low temperatures, and a potential difference appears between the low-temperature electrode E ₁ and the high-temperature electrode E ₂ . In other words, a type of concentration cell is formed due to the temperature difference.
Flowing from ₂ to E _1.

[0005]

By the way, the Br ₂ gas diffuses to the high temperature side through the gas bridge B ₁ and the electrode E ₁
Then, Br ₂ receives an electron and becomes Br ⁻ ion. Further, in the electrolyte Br ^- it is moved to the high temperature side from the low temperature side through a solution bridge B _2, emits electrons at E ₂ electrodes, the Br ₂ gas. In this battery, the low temperature side is the positive electrode, and the high temperature side is the negative electrode.

In a concentration cell utilizing such a temperature difference, ions do not participate in the electrode reaction, and when the temperature difference disappears, the electromotive force due to the concentration difference also disappears, and it is impossible to extract power. .

The present invention solves the problem that a conventional concentration cell does not have a power storage function. In addition to a normal power generation function using anions, each cation redox pair generated by a high-temperature electrode and a low-temperature electrode is stored. An object of the present invention is to provide a power storage type temperature difference battery having a power storage function by maintaining the concentration difference and forming a concentration cell, and enabling power generation even if the temperature difference disappears.

[0008]

That is, the present invention provides a ring-shaped electrolyte containing a cation redox pair whose oxidation-reduction potential changes with temperature and an electrolyte solution in which an anion which is a counter ion of the cation redox pair is gasified. In a temperature difference battery having a container and a pair of high and low temperature electrodes separated by a predetermined temperature difference in the container, the battery is disposed at a lower portion in the container and does not transmit through the cation redox pair. Equipped with a diaphragm, has a regular power generation function due to the difference in vapor pressure of gas between high and low temperatures, and accumulates each cation redox pair generated at the high and low temperature electrodes to generate a concentration difference, thereby providing a power storage function. And discharging when the temperature difference between the high and low temperature electrodes disappears so that the concentration difference between the cation redox pairs disappears.

[0009]

According to the present invention, a cation redox pair whose oxidation-reduction potential changes with temperature and an electrolyte solution in which an anion as the counter ion is gasified are separated from each other by a predetermined temperature difference in an annular container. Having a pair of high and low temperature electrodes,
Further, a septum that is impermeable to the cation redox pair is disposed at a lower portion of the container. With this, it has a normal power generation function by forming a concentration cell due to the gas vapor pressure difference between high and low temperatures, and causes a concentration difference by accumulating each cation redox pair generated at the high and low temperature electrodes. And a power storage function by forming a density cell. Further, when the temperature difference between the two electrodes disappears, discharge can be performed in a direction in which the concentration difference between the cation redox pair disappears.

[0010]

Embodiments of the present invention will be described below.

In the power storage type temperature difference battery of the present invention,
In order to cause a reaction in which an anion emits electrons to gasify and a reverse reaction thereof and a redox reaction of a cation redox pair on the same electrode, a redox pair compound in which the anion gasifies is used in the electrolyte. That is, by filling the electrolyte aqueous solution between the electrodes having different temperatures, a difference in gas and ion concentrations occurs between high and low temperatures, and a normal power generation function is exhibited by forming a concentration cell. At the same time, a cation redox pair whose oxidation-reduction potential changes with temperature causes a concentration difference by accumulating each cation redox pair generated at the high and low temperature electrodes, thereby forming a concentration cell, thereby achieving a power storage function. Have. Further, in order to realize such a function, an anion exchange membrane is used in which a cation redox pair does not permeate between the high and low temperature electrodes and an anion can permeate.

Here, the present invention will be described in detail by taking Br ^- as an example. Where M ^{Z +} and M ^{(Z + n) +} are valences Z
+, (Z + n) + cation redox. High temperature electrode (E ₂ ); 2Br ⁻ → Br ₂ + 2e ⁻ (ordinary power generation)… (1) M ^{(Z + n) +} + e ⁻ → M ^{Z +} (power storage)… (2) Low temperature electrode (E ₁ ) Br ₂ + 2e ⁻ → 2Br ⁻ (ordinary power generation) (3) M ^{Z +} → M ^{(Z + n) +} + e ⁻ (power storage) (4) No temperature difference E ₂ ; M ^{Z +} → M ^{(Z + n) +} + e ^- (density difference _{discharge) ... (5) E 1;} M (Z + n) + + e - when → M ^{Z +} (density difference discharge) ... (6) there is a temperature difference, the hot electrode (1) of The oxidation reaction of bromine and the reduction reaction of the formula (3) occur at the low-temperature electrode, and electrons flow from the high-temperature side to the low-temperature side. That is, the circuit current is
Flow from low temperature to high temperature. At the same time, a reduction reaction of the redox pair of the formula (2) occurs at the high-temperature electrode, and an oxidation reaction of the formula (4) occurs at the low-temperature electrode.

[0013] In the power storage type temperature difference battery of the present invention, Br ^- is transmitted, because it established a anion-exchange membrane impermeable to cations redox pair, it is on the hot electrode M ^{(Z + n ) +} is consumed along with the M ^{Z +} accumulation of, M ^{(Z + n) +} is accumulated together with the consumption of M ^{Z +} is on the low-temperature electrode. Therefore, the difference in concentration between M ^{Z +} and M ^{(Z + n) +} between both electrodes is enlarged.

By providing such a diaphragm, the concentration of M ^{Z +} on the high-temperature side and the concentration of M ^{(Z + n) +} on the low-temperature side increase, and by maintaining this difference in concentration, the electricity storage function is developed. . When the temperature difference between the electrodes E ₁ and E ₂ disappears, the power storage type temperature difference battery holding this concentration difference acts as a concentration cell. That is, in the direction of the E ₁ M ^{Z +} is increased, E ₂
Then, an electromotive force is generated in the direction in which M ^{(Z + n) +} increases,
The reaction of the above equations (5) and (6) proceeds, and current flows until the concentration difference between the two electrodes disappears. When quick charging is desired, an external voltage can be applied.

In the electric storage type temperature difference battery of the present invention, the above reaction can be efficiently advanced by using a graphite intercalation compound as an electrode material. In other words, by causing the charge transfer reaction of the electrolyte not only on the electrode surface but also between the graphite layers, a substantial reaction area is increased,
The current density per unit area can be increased.
Further, among the graphites, graphites having excellent orientation and crystallinity are preferable, and carbon fibers (VGCF) formed by a vapor phase growth method for easily forming an interlayer compound, and highly oriented heat-treated graphites (HOPG) formed by a high-temperature pressure treatment. Can be used. However, the electrode material is not particularly limited to graphite, and the gasification of the anion and its reverse reaction and the redox reaction of the redox couple may proceed on the same electrode. For example, a two-dimensional layered substance such as a transition metal dichalcogenide can be used.

Further, the electrolyte system used in the present invention is:
It is preferred that the cation redox couple has a positive thermoelectromotive force and that the value is as large as possible. This makes it possible to use a system in which anions are easily gasified, the vapor pressure has a large temperature dependence, and a layered substance and an interlayer compound are formed by charge transfer. As such,
FeBr ₂ / FeBr ₃ , CuBr / CuBr ₂ , Fe
Cl ₂ / FeCl ₃ , CuCl / CuCl ₂ , SbCl
₃ / SbCl ₅ , Fe (NO ₃ ) ₂ / Fe (N
Redox _couple electrolytes such as O ₃ ) ₃ and CuNO ₃ / Cu (NO ₃ ) ₂ are preferably used. That is, by selecting such a system, it becomes possible to develop a normal power generation function using anions and a power storage function using a cation redox pair. However, the electrolyte is not limited to these, and may be any electrolyte that satisfies the above characteristics.

Further, according to the present invention, it is possible to accumulate cation redox pairs by installing an anion exchange membrane having high ionic conductivity and low resistance which does not transmit cations but transmits anions. Becomes As such an anion exchange membrane, a polymer ion exchange membrane having various grades of amine groups, quaternary ammonium groups, sulfonium groups and the like can be used. However, the present invention is not limited to this, and any membrane that does not allow the cation redox pair to permeate may be used.

Next, an embodiment of the present invention will be described more specifically with reference to the drawings.

A highly oriented heat-treated graphite is added to a bromine solution at room temperature for 24 hours.
After immersion for a certain time, a part of the obtained product is quantitatively analyzed to be an intercalation compound having a composition of almost C ₁₆ Br. Furthermore, 5 × 10
By holding in a vacuum of ^-5 Torr for 1 hour, a graphite intercalation compound having a composition of C ₄₃ Br stable in the air can be obtained. According to X-ray diffraction, this is a high order interlayer compound of about the tenth stage.

FIG. 1 is a conceptual diagram showing an example of the configuration of a power storage type temperature difference battery according to the present invention. Electrodes E ₁ and E ₂ were fixed by lead wires 2 of platinum in an annular glass tube 10 having a diaphragm 11 of an anion exchange resin in the center.
The synthesized graphite intercalation compound 12 is filled. In this case, the weight of one electrode is 5 g. And, as an electrolyte, 10% FeBr ₂ / FeB saturated with Br ₂
The r ₃ aqueous solution 13 is injected from the injection valve 14 until the lower portions of the electrodes E ₁ and E ₂ are in contact with each other, and is sealed.

In such a state, the cell C ₁ side (negative electrode E ₁ ) is given at 20 ° C. by the low temperature medium 6 and the cell C ₂ side (positive electrode E ₂ ) is given at 80 ° C. by the high temperature side medium 7. Here, when an ammeter and a voltmeter are connected between the electrodes E ₁ and E ₂ , the open circuit voltage and the short circuit current value show a potential difference of about 85 mV and a current of about 125 mA. After 24 hours, when the electrodes E ₁ and E ₂ are brought to a constant temperature, a potential difference of about 35 mV and about 10
A current of mA is obtained. From this, Fe ²⁺ and Fe ²⁺
A concentration cell is formed due to the ³⁺ redox pair, and exhibits a power storage function.

Similarly, 1 saturated with Br ₂ was used as an electrolyte.
A 0% CuBr / CuBr ₂ aqueous solution 13 is applied to the electrodes E ₁ , E ₂
Until the lower part of the container comes in contact with the injection valve 14 and seal it. The cell C ₁ side (negative electrode E ₁ ) is set at 20 ° C. by the low temperature medium 6, and the cell C ₂ side (positive electrode E ₂ ) is set at 80 ° C. by the high temperature side medium 7, and an ammeter and a voltage are applied between the electrodes E ₁ and E _2. When the meter is connected, the open circuit voltage and the short circuit current value show a potential difference of about 80 mV and a current of about 130 mA. Then, after 24 hours, when the electrodes E ₁ and E ₂ are brought to a constant temperature, about 25 mV
And a current of about 13 mA can be obtained. Thus, C
It is possible to confirm the expression of the electricity storage function by the concentration cell due to the u ⁺ and Cu 2 ⁺ redox pair.

The same result as described above can be obtained when a graphite intercalation compound synthesized from vapor grown carbon fiber is used.

[0024]

As described above, according to the present invention, a normal temperature difference power generation function utilizing the vapor pressure difference of gas, and a redox pair being accumulated by a diaphragm utilizing heat (power storage function), and a concentration cell when the temperature difference disappears Can be discharged.
Furthermore, by using a graphite intercalation compound electrode having excellent orientation and crystallinity, the contact area with the electrolyte is increased to achieve a higher current density. It is extremely effective as a backup power supply for cogeneration. In addition, since the circulation action of the electrolyte due to the temperature difference is used, there is basically no moving part and the structure is maintenance-free, so that the effect of reducing the maintenance cost is great.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram showing an example of a configuration of a power storage type temperature difference battery according to the present invention.

FIG. 2 is a conceptual diagram showing a configuration example of a conventional temperature difference battery.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Graphite fiber intercalation compound, 2 ... Platinum lead wire, 3 ... Glass filter, 4 ... KBr electrolyte, 5 ... Electrolyte injection valve, 6
... low temperature medium (T ₁ ° C), 7 ... high temperature medium (T ₂ ° C), 10
... glass tube, 11 ... anion exchange membrane, 12 ... graphite intercalation compound, 13 ... KBr ₂ / KBr ₃ or CuBr / Cu
Br ₂ electrolyte solution, 14 electrolyte injection valve, B ₁ gas bridge, B ₂ solution bridge, C ₁ low temperature cell, C ₂ high temperature cell, E ₁ low temperature electrode, E ₂ high temperature electrode.

Continuation of the front page (56) References JP-A-6-82180 (JP, A) JP-A-6-140082 (JP, A) JP-A-5-166554 (JP, A) JP-A-4-94067 (JP) JP-A-9-149769 (JP, A) JP-A-2-121281 (JP, A) JP-A-58-145072 (JP, A) JP-A-55-30110 (JP, A) (58) Field surveyed (Int. Cl. ⁷ , DB name) H01M 14/00

Claims (4)

(57) [Claims] 1. An annular container containing an cation redox pair whose oxidation-reduction potential changes with temperature and an electrolyte solution in which an anion which is a counter ion of the cation redox pair is gasified. A temperature difference battery having a pair of high and low temperature electrodes separated by a temperature difference, comprising: a diaphragm disposed at a lower portion in the container and not permeating the cation redox pair; It has a normal power generation function caused by the vapor pressure difference of the gas, and has a power storage function by accumulating the respective cation redox pairs generated by the high and low temperature electrodes to generate a concentration difference. An energy storage type temperature difference battery, wherein when the difference disappears, the battery is discharged in a direction in which the concentration difference of the cation redox pair disappears. 2. The method according to claim 1, wherein the cation redox couple is Fe ²⁺ / F.
The energy storage type temperature difference battery according to claim 1, wherein e ³⁺ or Cu ⁺ / Cu ²⁺ , and a counter ion of the cation redox pair is a halogen or a nitrate ion. 3. The electric storage type temperature difference battery according to claim 1, wherein the high / low temperature electrode is formed of a graphite intercalation compound containing halogen, halide, or nitric acid as an intercalating substance. 4. The energy storage battery according to claim 1, wherein the diaphragm is formed of an anion exchange membrane having an amine group, a quaternary ammonium group, and a sulfonium group of each grade.