JP2016177868A - Redox flow battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a redox flow battery which has a high energy density and enables the suppression of precipitation of a precipitate such as a manganese oxide.SOLUTION: A Mn-Ti based redox flow battery 1 is arranged so that a positive electrode electrolyte and a negative electrode electrolyte are supplied to a battery cell including a positive electrode 104, a negative electrode 105 and a diaphragm 101 interposed between the electrodes to perform its charge and discharge. The positive electrode electrolyte includes manganese ions and reactive metal ions. The negative electrode electrolyte includes at least one kind of metal ions selected from titanium ions, chromium ions and zinc ions. The reactive metal ions are at least one kind of ions selected from vanadium ions, chromium ions, iron ions, cobalt ions, copper ions, molybdenum ions, ruthenium ions, palladium ions, silver ions, tungsten ions, mercury ions and cerium ions.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a redox flow battery. In particular, the present invention relates to a redox flow battery that can suppress the generation of precipitates and has a high energy density.

  In recent years, with the seriousness of power shortage, rapid introduction of natural energy such as wind power generation and solar power generation on a global scale and stabilization of the power system (for example, maintenance of frequency and voltage, etc.) have become issues. . As one of the countermeasure technologies, attention has been paid to installing large-capacity storage batteries to smooth output fluctuations, store surplus power, and level load.

  One of the large-capacity storage batteries is a redox flow battery (hereinafter sometimes referred to as an RF battery). RF batteries have features such as (1) easy to increase the capacity of megawatt class (MW class), (2) long life, and (3) the state of charge of the battery can be monitored accurately. Therefore, it is expected to be optimal as a storage battery for stabilizing power systems.

  In an RF battery, charging and discharging are performed by supplying a positive electrode electrolyte and a negative electrode electrolyte to battery cells in which a diaphragm is interposed between the positive electrode and the negative electrode, respectively. As the electrolytic solution for each electrode, a solution containing, as an active material, a metal ion whose valence changes by oxidation and reduction is typically used. Typical examples include an Fe-Cr RF battery using iron (Fe) ions as a positive electrode active material and chromium (Cr) ions as a negative electrode active material, and a V RF battery using vanadium (V) ions as active materials of both electrodes ( Paragraph 0003 of the specification of Patent Document 1).

In Patent Document 1, an Mn-Ti system using manganese (Mn) ions as a positive electrode active material and titanium (Ti) ions as a negative electrode active material as an RF battery capable of obtaining a higher electromotive force than a conventional V-type RF battery. An RF battery is disclosed. In Patent Document 1, by containing together titanium ions in the positive electrode electrolyte solution, it is possible to suppress the generation of precipitates such as manganese oxide (MnO _2), it can be performed stably reaction of Mn 2+ ^/ Mn ³⁺ Is disclosed.

Japanese Patent No. 4835792

  Development of a redox flow battery with higher energy density is desired.

  In the Mn—Ti-based RF battery disclosed in Patent Document 1, the generation of precipitates can be suppressed as described above by containing titanium ions in the positive electrode electrolyte. However, the titanium ions in the positive electrode electrolyte basically do not function as a positive electrode active material and do not contribute to charge / discharge. Therefore, when the total concentration of metal ions in the positive electrode electrolyte is constant, the ratio of the active material in the positive electrode electrolyte is relatively decreased due to the inclusion of titanium ions, and the energy density is lowered. Further, for example, in order to use an electrolytic solution with a small proportion of the active material as a redox flow battery having a long capacity, it is necessary to use a large amount of the electrolytic solution. Then, the capacity of the tank increases, the size of the entire RF battery system due to the increase in the tank (enlargement of the installation space), the increase in the electrolyte cost, and the like are caused.

  Accordingly, one of the objects of the present invention is to provide a redox flow battery that can suppress the generation of precipitates and has a high energy density.

  The redox flow battery of the present invention performs charge and discharge by supplying a positive electrode electrolyte and a negative electrode electrolyte to a battery cell including a positive electrode, a negative electrode, and a diaphragm interposed between the two electrodes. The positive electrode electrolyte contains manganese ions and reactive metal ions. The negative electrode electrolyte contains at least one metal ion selected from titanium ions, chromium ions, and zinc ions. The reactive metal ion is at least one selected from vanadium ion, chromium ion, iron ion, cobalt ion, copper ion, molybdenum ion, ruthenium ion, palladium ion, silver ion, tungsten ion, mercury ion and cerium ion. .

  The redox flow battery of the present invention can suppress generation of precipitates and has a high energy density.

It is explanatory drawing which shows the operation principle of a battery system provided with the redox flow battery of embodiment.

[Description of Embodiment of the Present Invention]
In order to improve the energy density of the redox flow battery using manganese ions as the positive electrode active material, the present inventors have studied using a plurality of ion species that function as the active material. As a result, the inventors have obtained a surprising finding that specific metal ions function as an active material in the positive electrode electrolyte and can suppress the generation of precipitates such as manganese oxides. Based on this finding, a configuration is proposed in which the positive electrode electrolyte separately includes metal ions that function as an active material and have an effect of suppressing precipitates, in addition to manganese ions that are positive electrode active materials. First, the contents of the embodiment of the present invention will be listed and described.

  (1) The redox flow battery according to the embodiment performs charge and discharge by supplying a positive electrode electrolyte and a negative electrode electrolyte to a battery cell including a positive electrode, a negative electrode, and a diaphragm interposed between the two electrodes. . The positive electrode electrolyte contains manganese ions and reactive metal ions. The negative electrode electrolyte contains at least one metal ion selected from titanium ions, chromium ions, and zinc (Zn) ions. The reactive metal ions include vanadium ions, chromium ions, iron (Fe) ions, cobalt (Co) ions, copper (Cu) ions, molybdenum (Mo) ions, ruthenium (Ru) ions, palladium (Pd) ions, silver It is at least one selected from (Ag) ions, tungsten (W) ions, mercury (Hg) ions, and cerium (Ce) ions. The said reactive metal ion means what has a function as a positive electrode active material, and the function which suppresses precipitation of a deposit.

  Since the RF battery of the embodiment uses manganese ions contained in the positive electrode electrolyte as the positive electrode active material, (1) the electromotive force can be increased as compared with a conventional V-type RF battery, (2) Since manganese ions are water-soluble metal ions, the electrolytic solution can be made into an aqueous solution and excellent in manufacturability. (3) Manganese ions are relatively inexpensive and preferable from the viewpoint of resource supply. Play. In the RF battery of the embodiment, the specific metal ion (reactive metal ion) contained in the positive electrode electrolyte also functions as the positive electrode active material, so that the ratio of the active material in the electrolyte can be increased. Therefore, the RF battery of the embodiment has a higher energy density than an RF battery including a positive electrode electrolyte that includes manganese ions and titanium ions and does not include the reactive metal ions. In addition, since the RF battery of the embodiment can suppress the generation of precipitates, even when the state of charge is increased, an increase in cell resistance due to the precipitates can be suppressed, and the cell resistance is low. Thus, the RF battery of the embodiment has excellent battery characteristics. Furthermore, the RF battery of the embodiment can reduce the size of the tank, the installation space, the cost of the electrolyte, and the like.

  (2) As an example of the RF battery of the embodiment, a form in which the positive electrode electrolyte further contains an added metal ion can be mentioned. The additive metal ions include aluminum (Al) ions, cadmium (Cd) ions, indium (In) ions, tin (Sn) ions, antimony (Sb) ions, iridium (Ir) ions, gold (Au) ions, lead ( Pb) at least one selected from ions and bismuth (Bi) ions. The said additive metal ion means what has a function which does not function as an active material substantially, but suppresses precipitation of a deposit.

  As a result of the study by the present inventors, the above-mentioned specific metal ions (added metal ions) are present together with manganese ions in the positive electrode electrolyte, thereby suppressing the generation of precipitates such as manganese oxides. I got the knowledge. In particular, the inventors have found that the additive metal ions can suppress the generation of precipitates even if the content of the added metal ions is very small. The said form can suppress generation | occurrence | production of a precipitate more effectively by containing an addition metal ion in addition to a reactive metal ion. Moreover, the said form can suppress the fall of the ratio of the active material in electrolyte solution by reducing content of an addition metal ion, and can have a high energy density.

  (3) As an example of the RF battery of the embodiment, a form in which the concentration of the reactive metal ions in the positive electrode electrolyte (total concentration in a plurality of cases) is 0.001M or more and 5M or less. M shown as a unit of concentration means volume molar concentration, that is, mol / L (mol / liter). Hereinafter, the same applies to the concentration.

  The said form contains a reactive metal ion in the above-mentioned specific range, (1) It can utilize a reactive metal ion favorably as an active material, and can have a high energy density, (2) Precipitate (3) Even when the electrolytic solution is an aqueous acid solution, it can be dissolved satisfactorily, and the electrolytic solution is excellent in manufacturability.

  (4) As an example of the RF battery of the embodiment, when the above-described additive metal ions are contained, the concentration of the additive metal ions in the positive electrode electrolyte (the total concentration in the case of a plurality) is 0.001M or more and 1M or less. One form is mentioned.

  The said form can suppress generation | occurrence | production of a precipitate effectively by containing an additional metal ion in the above-mentioned specific range.

  (5) As an example of the RF battery of the embodiment, there is a mode in which at least one of the manganese ion concentration in the positive electrode electrolyte and the metal ion concentration in the negative electrode electrolyte is 0.3 M or more and 5 M or less. . When the metal ions contained in the negative electrode electrolyte are plural kinds, the total concentration is used.

  The said form contains the metal ion which functions as an active material of each pole in the above-mentioned specific range, (i) It can fully contain the metal element which performs a valence change reaction, and can have a high energy density. (Ii) Even when the electrolytic solution is an aqueous acid solution, it can be dissolved satisfactorily, and the electrolytic solution is excellent in manufacturability.

  (6) As an example of the RF battery of the embodiment, the negative electrode electrolyte contains titanium ions as the metal ions, the concentration of the manganese ions in the positive electrode electrolyte, and the concentration of the titanium ions in the negative electrode electrolyte. The form whose at least one is 0.3M or more and 5M or less is mentioned.

  The said form can be set as the Mn-Ti type | system | group RF battery with a high energy density because the density | concentration of the said manganese ion and the density | concentration of the said titanium ion satisfy | fill a specific range, and also described in the said form (5) ( The effect of ii) is also achieved.

(7) As an example of the RF battery of the embodiment, the reactive metal ion may have a form satisfying at least one of the following (A) to (L).
(A) The vanadium ion is a divalent vanadium ion, a trivalent vanadium ion, a tetravalent vanadium ion, or a pentavalent vanadium ion. (B) The chromium ion is a divalent chromium ion, 3 (C) The iron ion is at least one of a divalent iron ion and a trivalent iron ion (D) The cobalt ion is at least one of a divalent cobalt ion and a trivalent cobalt ion. (E) The copper ion is at least one of a monovalent copper ion and a divalent copper ion. (F) The molybdenum ion. Is at least one of a tetravalent molybdenum ion, a pentavalent molybdenum ion, and a hexavalent molybdenum ion. (G) The mu ion is at least one of a divalent ruthenium ion, a trivalent ruthenium ion, and a tetravalent ruthenium ion. (H) The palladium ion is at least one of a divalent palladium ion and a tetravalent palladium ion. I) The silver ion is at least one of a monovalent silver ion and a divalent silver ion. (J) The tungsten ion is at least a tetravalent tungsten ion, a pentavalent tungsten ion, and a hexavalent tungsten ion. (K) The mercury ion is at least one of monovalent mercury ion and divalent mercury ion. (L) The cerium ion is at least one of trivalent cerium ion and tetravalent cerium ion. is there

  The metal ions having each valence listed above function as a positive electrode active material and exhibit the effect of suppressing precipitates. Thus, the above form has high energy density and can suppress the generation of precipitates.

  (8) As an example of the RF battery according to the embodiment, the negative electrode electrolyte may further include a manganese ion.

  In the above form, both the positive electrode electrolyte and the negative electrode electrolyte contain manganese ions. That is, in the above form, at least one ionic species existing in the electrolyte solution of both electrodes overlaps. Therefore, for example, even when the manganese ions of the positive electrode move to the negative electrode over time, it is easy to avoid a decrease in battery capacity due to the reduction of the positive electrode active material by moving the manganese ions of the negative electrode to the positive electrode.

  (9) As an example of the RF battery of the embodiment, the negative electrode electrolyte may further include manganese ions and the reactive metal ions.

  In the above form, both the positive electrode electrolyte and the negative electrode electrolyte contain manganese ions and reactive metal ions. That is, in the above embodiment, both of the electrolyte solutions of both electrodes include a plurality of ion species, and a plurality of ion species existing in the electrolyte solution of both electrodes overlap. Therefore, in the above-described embodiment, (i) it is easy to avoid a decrease in battery capacity due to the above-described reduction in active material over time, (ii) liquid transfer with time along with charge / discharge (the electrolyte of one electrode is the other) Even if there is a variation in the amount of electrolyte solution in both electrodes due to the phenomenon of movement to the other electrode, it is easy to correct, and (iii) it is excellent in the productivity of the electrolyte solution.

  (10) As an example of the RF battery of the embodiment, when the positive electrode electrolyte contains the above-described added metal ions, the negative electrode electrolyte further contains manganese ions, the reactive metal ions, and the added metal ions. The form to include is mentioned.

  The said form contains a manganese ion, a reactive metal ion, and an addition metal ion in both a positive electrode electrolyte solution and a negative electrode electrolyte solution. In other words, in the above embodiment, both the electrolytes of both electrodes contain a plurality of ionic species, and the plurality of ionic species existing in the electrolytes of both electrodes overlap. Therefore, as in the above-described form (9), the above-described form is (i) it is easy to avoid a decrease in battery capacity due to the reduction of the active material over time, and (ii) the liquid is changed over time with charge / discharge. Even if there is a variation in the amount of electrolyte solution in both electrodes due to the transfer, it is easy to correct, and (iii) the electrolyte solution is excellent in productivity.

  (11) As an example of the RF battery of the embodiment, when the negative electrode electrolyte contains manganese ions, a form in which the concentration of manganese ions in the negative electrode electrolyte is 0.3 M or more and 5 M or less.

  The said form has an effect similar to the above-mentioned form (8)-(10). Specifically, the said form can suppress the reduction | decrease of the battery capacity by the reduction | decrease of the positive electrode active material with time at least. Furthermore, the said form can melt | dissolve favorably even when making electrolyte solution into the aqueous solution of an acid because the density | concentration of the manganese ion in negative electrode electrolyte solution is the above-mentioned specific range, and it is excellent in manufacturability of electrolyte solution.

(12) As an example of the RF battery according to the embodiment, when the positive electrode electrolyte contains the additional metal ion, the additional metal ion satisfies at least one of the following (a) to (i).
(A) The aluminum ion is a monovalent aluminum ion, a divalent aluminum ion, or a trivalent aluminum ion. (B) The cadmium ion is a monovalent cadmium ion or a divalent cadmium ion. (C) The indium ion is at least one of monovalent indium ion, divalent indium ion, and trivalent indium ion. (D) The tin ion is divalent tin ion and tetravalent. (E) the antimony ion is a trivalent antimony ion and at least one of a pentavalent antimony ion (f) the iridium ion is a monovalent iridium ion or a divalent iridium ion Trivalent iridium ion, tetravalent iridium ion, pentavalent iri (G) The gold ion is a monovalent gold ion, a divalent gold ion, a trivalent gold ion, a tetravalent gold ion, or a pentavalent gold ion. (H) the lead ion is at least one of a divalent lead ion and a tetravalent lead ion (i) the bismuth ion is at least a trivalent bismuth ion and a pentavalent bismuth ion On the other hand

  Since the metal ions having the respective valences listed have the effect of suppressing precipitates, the above-described form contains the added metal ions having the respective valences in addition to the reactive metal ions, thereby generating precipitates. Can be more effectively suppressed.

  (13) As an example of the RF battery of the embodiment, the manganese ion is at least one of a divalent manganese ion and a trivalent manganese ion, and the negative electrode electrolyte contains titanium ions as the metal ions. The form whose titanium ion is at least one of a trivalent titanium ion and a tetravalent titanium ion is mentioned.

  The listed manganese ions function as a positive electrode active material in the positive electrode electrolyte, and the listed titanium ions function as a negative electrode active material. An Mn-Ti RF battery can be constructed. In the case where manganese ions of each valence listed are also contained in the negative electrode electrolyte, the same effect as in the above embodiments (8) to (10), that is, the battery capacity due to at least the reduction of the positive electrode active material over time Can be suppressed.

[Details of the embodiment of the present invention]
Hereinafter, a redox flow battery according to an embodiment of the present invention will be described in detail. In addition, this invention is not limited to these illustrations, is shown by the claim, and is intended that all the changes within the meaning and range equivalent to the claim are included. For example, in the test examples described later, the concentration of manganese ions in the positive electrode electrolyte, the type / concentration of metal ions (negative electrode active material) in the negative electrode electrolyte, the type of acid / acid concentration, and the reactivity of the electrolyte in each electrode The type / concentration of the metal ions / additional metal ions, the amount of the electrolyte, the material / size of the electrode, the material of the diaphragm, and the like can be appropriately changed. In addition, in the test examples described later, an additive metal ion can be added to the electrolyte solution of at least one electrode.

  First, with reference to FIG. 1, the outline | summary of a battery system provided with the redox flow battery which concerns on embodiment is demonstrated, and electrolyte solution is demonstrated in detail after that. The element shown in the tank of FIG. 1 shows an example of ionic species contained in the electrolytic solution. In FIG. 1, a solid line arrow means charging, and a broken line arrow means discharging.

(overall structure)
The redox flow battery (RF battery) 1 of the embodiment typically includes a power generation unit 300 (for example, a solar power generator, a wind power generator, and the like, via an AC / DC converter 200, a transformer facility 210, and the like. A general power plant or the like) is connected to a load 400 such as a power system or a customer, and charging is performed using the power generation unit 300 as a power supply source and discharging is performed using the load 400 as a power supply target. In performing charging / discharging, the following battery system including the RF battery 1 and a circulation mechanism (tank, conduit, pump) for circulating the electrolyte in the RF battery 1 is constructed.

  The RF battery 1 includes a positive electrode cell 102 containing a positive electrode 104, a negative electrode cell 103 containing a negative electrode 105, and a diaphragm 101 that separates the cells 102 and 103 and transmits predetermined ions. Is a main component. A positive electrode electrolyte tank 106 is connected to the positive electrode cell 102 via conduits 108 and 110. A negative electrode electrolyte tank 107 is connected to the negative electrode cell 103 via conduits 109 and 111. The conduits 108 and 109 are provided with pumps 112 and 113 for circulating the electrolyte solution of each electrode. The RF battery 1 uses the conduits 108 to 111 and the pumps 112 and 113 to the positive electrode cell 102 (positive electrode 104) and the negative electrode cell 103 (negative electrode 105), respectively. The electrolyte solution is circulated and supplied, and charging / discharging is performed in accordance with the valence change reaction of the metal ion that becomes the active material in the electrolyte solution of each electrode.

  The RF battery 1 typically uses a form called a cell stack including a plurality of battery cells 100. Here, the cells 102 and 103 include a bipolar plate (not shown) in which the positive electrode 104 is disposed on one surface and the negative electrode 105 is disposed on the other surface, a supply hole for supplying an electrolytic solution, and an exhaust for discharging the electrolytic solution. A configuration using a cell frame having a liquid hole and having a frame (not shown) formed on the outer periphery of the bipolar plate is representative. By laminating a plurality of cell frames, the liquid supply hole and the drainage hole constitute an electrolyte flow path, and the flow path is connected to the conduits 108 to 111. The cell stack is configured by repeatedly stacking a cell frame, a positive electrode 104, a diaphragm 101, a negative electrode 105, a cell frame,. As the basic configuration of the RF battery system, a known configuration can be appropriately used.

  In the RF battery 1 of the embodiment, the positive electrode electrolyte contains manganese ions, and the negative electrode electrolyte contains at least one metal ion selected from titanium ions, chromium ions, and zinc ions. And in the RF battery 1 of embodiment, a reactive metal ion is contained as a specific metal ion which has a some function further in positive electrode electrolyte solution.

(Electrolyte)
-Positive electrode electrolyte-Manganese ion The positive electrode electrolyte with which the RF battery 1 of embodiment contains manganese ion as a positive electrode active material. Manganese ions have at least one valence ion in the positive electrode electrolyte. For example, a divalent manganese ion and a trivalent manganese ion can be mentioned. Furthermore, tetravalent manganese may be contained. This tetravalent manganese is considered to be MnO ₂ . However, this MnO ₂ is not a solid precipitate but exists in a stable state as dissolved in the electrolyte, and is reduced to Mn ²⁺ by a two-electron reaction (Mn ⁴⁺ + 2e ⁻ → Mn ²⁺ ) during discharge. In other words, it can be discharged to act as an active material and be used repeatedly, which may contribute to an increase in battery capacity. Therefore, the presence of a slight amount (about 10% or less of the total amount (mol) of manganese ions) of tetravalent manganese is allowed in the positive electrode electrolyte.

Examples of the manganese ion concentration (hereinafter referred to as Mn content) in the positive electrode electrolyte include 0.3M or more and 5M or less. When it is 0.3 M or more, a sufficient energy density (for example, about 10 kWh / m ³ ) as a large-capacity storage battery can be obtained. Since the energy density is increased as the Mn content is higher, the Mn content can be set to 0.5 M or more, and further 1.0 M or more. In the RF battery 1 according to the embodiment, by containing the reactive metal ions described later in the positive electrode electrolyte, even if the concentration of manganese ions is increased, the generation of precipitates can be suppressed, and the manganese ions can be stabilized. Be present. However, considering the solubility in a solvent, the Mn content is easily 5M or less, more preferably 2M or less, and the productivity of the electrolytic solution is excellent.

-Reactive metal ion The positive electrode electrolyte solution with which RF battery 1 of embodiment is equipped contains a reactive metal ion further. This reactive metal ion functions as a positive electrode active material, and also functions as an inhibitor for the generation of precipitates such as manganese oxide. The specific reactive metal ion is at least one selected from vanadium ion, chromium ion, iron ion, cobalt ion, copper ion, molybdenum ion, ruthenium ion, palladium ion, silver ion, tungsten ion, mercury ion and cerium ion. Is mentioned. Each reactive metal ion has at least one valence ion in the positive electrode electrolyte. For example, (A) vanadium ions include divalent vanadium ions, trivalent vanadium ions, tetravalent vanadium ions, and pentavalent vanadium ions. Examples of (B) chromium ions include divalent chromium ions, trivalent chromium ions, tetravalent chromium ions, and hexavalent chromium ions. (C) The iron ion includes a divalent iron ion and a trivalent iron ion. Examples of (D) cobalt ions include divalent cobalt ions and trivalent cobalt ions. (E) The copper ion includes a monovalent copper ion and a divalent copper ion. Examples of (F) molybdenum ions include tetravalent molybdenum ions, pentavalent molybdenum ions, and hexavalent molybdenum ions. (G) Ruthenium ions include divalent ruthenium ions, trivalent ruthenium ions, and tetravalent ruthenium ions. Examples of (H) palladium ions include divalent palladium ions and tetravalent palladium ions. (I) Silver ions include monovalent silver ions and divalent silver ions. (J) Examples of tungsten ions include tetravalent tungsten ions, pentavalent tungsten ions, and hexavalent tungsten ions. Examples of (K) mercury ions include monovalent mercury ions and divalent mercury ions. Examples of (L) cerium ions include trivalent cerium ions and tetravalent cerium ions. There may be other valences than those listed. In some cases, ions of the same element but different in valence are included. Furthermore, the case where these elements exist as a metal (solid) in addition to ions is allowed.

  The standard oxidation-reduction potential (potential) of each metal ion listed as a reactive metal ion is a lower potential or a higher potential than that of manganese ions. For this reason, these metal ions are contained together with manganese ions in the positive electrode electrolyte solution, so that the valence change reaction is sequentially performed substantially in accordance with the potential and functions as a positive electrode active material. Of the metal ions listed above, any of a form containing a single type of reactive metal ion and a form containing a plurality of types of reactive metal ions can be used. In particular, when vanadium ions are included as reactive metal ions, the vanadium ions have a track record as an active material for conventional V-type RF batteries, so that the reliability of the battery can be improved.

  Examples of the concentration of the reactive metal ions in the positive electrode electrolyte (the total concentration when a plurality of types of reactive metal ions are included) are 0.001M or more and 5M or less. When it is 0.001 M or more, reactive metal ions can be effectively used as a positive electrode active material together with manganese ions, and the ratio of the positive electrode active material in the positive electrode electrolyte can be increased. Therefore, the RF battery 1 having a high energy density can be obtained. Moreover, generation | occurrence | production of a precipitate can be suppressed even if the positive electrode electrolyte solution does not contain a titanium ion as it is 0.001M or more. The higher the concentration of the reactive metal ion, the higher the energy density, and the easier it is to suppress the precipitates. However, considering the solubility in a solvent, the concentration of the reactive metal ion in the positive electrode electrolyte is 5M or less, and more preferably 2M or less, which is excellent in the productivity of the electrolyte. Here, when the electrolytic solution is an aqueous acid solution, the generation of precipitates can be suppressed by increasing the acid concentration to some extent, as will be described later. However, increasing the acid concentration causes a decrease in the solubility of the metal ions. Since the RF battery 1 of the embodiment can suppress the generation of precipitates by containing reactive metal ions, it is not necessary to excessively increase the acid concentration, and the metal ion concentration should be within a practical range. it can. Either the same or different manganese ion concentration and reactive metal ion concentration can be used.

-Addition metal ion The positive electrode electrolyte solution with which the RF battery 1 of embodiment is equipped can contain further the ion which has an inhibitory effect with respect to generation | occurrence | production of deposits, such as manganese oxide. Examples of such ions include at least one selected from aluminum ions, cadmium ions, indium ions, tin ions, antimony ions, iridium ions, gold ions, lead ions, and bismuth ions. Each metal ion has at least one valence ion in the positive electrode electrolyte. For example, (a) aluminum ions include monovalent aluminum ions, divalent aluminum ions, and trivalent aluminum ions. (B) Cadmium ions include monovalent cadmium ions and divalent cadmium ions. (C) Indium ions include monovalent indium ions, divalent indium ions, and trivalent indium ions. (D) As for a tin ion, a bivalent tin ion and a tetravalent tin ion are mentioned. (E) Antimony ions include trivalent antimony ions and pentavalent antimony ions. (F) Examples of iridium ions include monovalent iridium ions, divalent iridium ions, trivalent iridium ions, tetravalent iridium ions, pentavalent iridium ions, and hexavalent iridium ions. (G) Gold ions include monovalent gold ions, divalent gold ions, trivalent gold ions, tetravalent gold ions, and pentavalent gold ions. (H) Lead ions include divalent lead ions and tetravalent lead ions. (I) Bismuth ions include trivalent bismuth ions and pentavalent bismuth ions. There may be other valences than those listed. In some cases, ions of the same element but different in valence are included. Furthermore, the case where these elements exist as a metal (solid) in addition to ions is allowed.

  In addition, lithium (Li) ion, beryllium (Be) ion, sodium (Na) ion, magnesium (Mg) ion, potassium (K) ion, calcium (Ca) ion, scandium (Sc) ion, nickel (Ni) ion, Zinc (Zn) ion, gallium (Ga) ion, germanium (Ge) ion, rubidium (Rb) ion, strontium (Sr) ion, yttrium (Y) ion, zirconium (Zr) ion, niobium (Nb) ion, technetium ( Tc) ion, rhodium (Rh) ion, cesium (Cs) ion, barium (Ba) ion, ion of lanthanoid element (excluding cerium), hafnium (Hf) ion, tantalum (Ta) ion, rhenium (Re) ion , Osmium (Os) ion, white (Pt) ion, thallium (Tl) ion, polonium (Po) ion, francium (Fr) ion, radium (Ra) ion, actinium (Ac) ion, thorium (Th) ion, protoactinium (Pa) ion, uranium ( U) ions are expected to have an inhibitory effect on the generation of precipitates such as manganese oxides. Accordingly, at least one metal ion listed above can be expected to be used as an additive metal ion.

  Each metal ion enumerated as an additive metal ion is effective in suppressing the generation of the above-mentioned precipitates, even if it is in a trace amount, and therefore suppresses a decrease in the ratio of the active material accompanying the inclusion of the additive metal ion in the electrolyte. easy. Each of the metal ions listed above mainly functions as an inhibitor of the generation of the precipitate, and does not substantially function as an active material. However, some ionic species may function as an active material (for example, lead ions). When the added metal ion also functions as a positive electrode active material, the energy density can be further increased. Of the metal ions listed above, any of a form containing a single kind of added metal ion and a form containing a plurality of kinds of added metal ions can be used.

  Examples of the concentration of the added metal ions in the positive electrode electrolyte (the total concentration when a plurality of types of added metal ions are included) include 0.001 M or more and 1 M or less. Generation | occurrence | production of a precipitate can be effectively suppressed with a reactive metal ion as it is 0.001M or more. Since the concentration of the added metal ions is expected to increase the effect of suppressing the precipitate as the concentration increases, it can be 0.005M or more, and further 0.01M or more. However, if the concentration of the added metal ion is too high, the ratio of the active material in the electrolytic solution is lowered, and consequently the energy density is lowered. Therefore, the concentration of the added metal ion is preferably 0.8M or less, more preferably 0.5M or less.

-Negative electrode electrolyte The negative electrode electrolyte with which the RF battery 1 of embodiment is equipped contains at least 1 type of metal ion selected from a titanium ion, chromium ion, and zinc ion as a negative electrode active material. Any of these metal ions can be combined with manganese ions as the positive electrode active material to form a redox pair having a high electromotive force. Each metal ion used as the negative electrode active material has at least one valence ion in the negative electrode electrolyte. There are cases in which ions of the same element and different valences are included. Moreover, the case where these elements exist as a metal (solid) in addition to ions is allowed. Of each of the listed metal ions, either a form containing a single kind of metal ion or a form containing a plurality of kinds of metal ions can be used.

  In particular, an electromotive force of about 1.4 V can be obtained in a Mn-Ti RF battery containing titanium ions as a negative electrode active material. Also, when titanium ions are included as the negative electrode active material, titanium ions move over time due to repeated charge and discharge and mixed into the positive electrode electrolyte from the negative electrode electrolyte. It can function as an inhibitor for the generation of precipitates. The titanium ion in the negative electrode electrolyte contains at least one valence ion. For example, a trivalent titanium ion and a tetravalent titanium ion can be mentioned.

  When a plurality of types of metal ions are contained as the negative electrode active material, a combination that takes into account the standard oxidation-reduction potential (potential) of each metal ion, that is, a combination of a noble potential and a base potential Similarly to the positive electrode electrolyte, the negative electrode electrolyte can increase the utilization rate of metal ions and improve the energy density.

Examples of the concentration of each metal ion listed as the negative electrode active material (the total concentration when a plurality of types of metal ions are included) include 0.3 M or more and 5 M or less. When it is 0.3 M or more, a sufficient energy density (for example, about 10 kWh / m ³ ) as a large-capacity storage battery can be obtained. Since the energy density increases as the concentration of the metal ion in the negative electrode electrolyte increases, it can be set to 0.5 M or more, and further 1.0 M or more. However, considering the solubility in the solvent, the concentration of the metal ion in the negative electrode electrolyte is easily 5M or less, more preferably 2M or less, and the productivity of the electrolyte is excellent. In particular, when titanium ions are contained in the range of 0.3 M or more and 5 M or less as the negative electrode active material, a Mn—Ti RF battery having a high energy density as described above can be obtained. The total form of the concentration of manganese ions that mainly function as a positive electrode active material and the concentration of reactive metal ions in the positive electrode electrolyte and the concentration of metal ions that mainly function as the negative electrode active material in the negative electrode electrolyte are the same, Any of the different forms can be used.

  The negative electrode electrolyte can contain at least one of the above-mentioned ionic species of the added metal ions. That is, at least one of the positive electrode electrolyte and the negative electrode electrolyte can be in a form containing an additive metal ion. When the negative electrode electrolyte contains at least one kind of added metal ion, (1) the battery reactivity of the metal ion functioning as the negative electrode active material can be increased (the reaction rate can be increased), and (2) depending on the ionic species, the active material (3) the generation of hydrogen accompanying water decomposition can be suppressed.

In addition, the negative electrode electrolyte solution can include the above-described metal ions such as titanium ions serving as a negative electrode active material, and can have the following form.
(A) A form containing manganese ions.
(B) A form containing at least one of the same ionic species as the reactive metal ion contained in the positive electrode electrolyte.
(C) A form in which at least one of the same ionic species is included when the positive electrode electrolyte contains at least one of the ionic species of the additive metal ions listed above.
(D) A form satisfying two of the above forms (a) to (c) (for example, form (a) + form (b)).
(E) A form satisfying all of the above forms (a) to (c).

  In any of the above-described forms (a) to (e), at least one ion species contained in the positive electrode electrolyte and the negative electrode electrolyte overlaps. Therefore, these forms are (i) easy to avoid a decrease in battery capacity due to a decrease in active material over time, (ii) easy to correct variations in the amount of electrolyte in both electrodes due to liquid transfer, (iii) There are effects that it is easy to suppress a change in concentration caused by the movement of metal ions to the counter electrode, and (iv) it is easy to produce an electrolyte solution. For example, in the form (a), it is easy to suppress at least a decrease with time of the positive electrode active material. For example, in a form in which the negative electrode electrolyte contains chromium ions and manganese ions and the reactive metal ions of the positive electrode electrolyte are chromium ions, all ionic species can match. The concentration of the metal ion overlapping in the electrolyte solution of both electrodes can be used either in a different form in both electrodes or in an equal form in both electrodes. As for the valence of the metal ions overlapping in the electrolyte solution of both electrodes, either a different form in both electrodes or an equal form in both electrodes can be used. If all the ionic species existing in the electrolyte solution of both electrodes are matched, and if the concentrations are further matched, one electrolyte solution can be used as the electrolyte solution of both electrodes, and the productivity of the electrolyte solution is further improved.

  More specifically, the negative electrode electrolyte contains titanium ions and manganese ions (a), the negative electrode electrolyte contains titanium ions, manganese ions, and reactive metal ions of the same ionic species contained in the positive electrode electrolyte. Form (d) (form (a) + form (b)), form in which the negative electrode electrolyte contains titanium ions, manganese ions, and reactive metal ions and added metal ions of the same ionic species contained in the positive electrode electrolyte ( e). When the reactive metal ion contained in the electrolyte solution of both electrodes is vanadium ion, the vanadium ion in the electrolyte solution of each electrode can function as a positive electrode active material and a negative electrode active material. Thus, in the form in which the negative electrode electrolyte contains manganese ions, the concentration of manganese ions in the negative electrode electrolyte is, for example, 0.3 M or more and 5 M or less. If it is this concentration range, it will be easy to melt | dissolve as mentioned above, and it is excellent also in manufacturability of electrolyte solution. When the negative electrode electrolyte contains manganese ions, for example, divalent manganese ions and trivalent manganese ions can be mentioned. In addition, when reactive metal ions or additive metal ions are included in the electrolyte solution of both electrodes, at least one ion species of each electrode can include different ions.

-Solvent of electrolyte solution etc. All the metal ions contained in the electrolyte solution of each above-mentioned electrode are water-soluble ions. Therefore, an aqueous solution containing water as a solvent can be suitably used for the positive electrode electrolyte and the negative electrode electrolyte. In particular, when the electrolytic solution is an aqueous solution of an acid containing sulfuric acid or sulfate, (1) When the stability of various metal ions is improved, the reactivity of metal ions as an active material is improved, and the solubility is improved. (2) Even when metal ions having a high potential such as manganese ions are used, side reactions are unlikely to occur (degradation is unlikely to occur), (3) ion conductivity is high, and internal resistance of the battery is reduced. (4) Unlike the case where hydrochloric acid is used, a plurality of effects can be expected, such as no generation of chlorine gas, (5) an electrolyte can be easily obtained using sulfate and the like, and excellent manufacturability. The acid aqueous solution (electrolytic solution) prepared using the above sulfuric acid or sulfate includes, for example, sulfate anion (SO ₄ ²⁻ ). When the electrolytic solution is an acid solution, the generation of precipitates such as manganese oxide can be suppressed to some extent by increasing the acid concentration. In an electrolytic solution containing metal ions capable of suppressing the generation of precipitates such as reactive metal ions, the generation of precipitates may be suppressed even if the acid concentration in the electrolytic solution is lowered to some extent. As the electrolytic solution, an aqueous solution prepared using a known acid or a known salt in addition to sulfuric acid or a sulfate can be used.

(Other configurations)
-Electrode The materials of the positive electrode 104 and the negative electrode 105 include those mainly composed of carbon fiber, for example, non-woven fabric (carbon felt) and paper. When using an electrode made of carbon felt, (1) when an aqueous solution is used as the electrolyte, oxygen gas is hardly generated even when the oxygen generation potential is reached during charging, (2) the surface area is large, (3) the electrolyte It has the effect of being excellent in the distribution of Known electrodes can be used.

-Diaphragm As the diaphragm 101, for example, an ion exchange membrane such as a cation exchange membrane or an anion exchange membrane can be mentioned. The ion exchange membrane has the effects of (1) excellent separation between the metal ions of the positive electrode active material and the metal ions of the negative electrode active material, and (2) excellent permeability of H ⁺ ions (charge carriers inside the battery). Yes, it can be suitably used for the diaphragm 101. A known diaphragm can be used.

  Hereinafter, the stability of the electrolytic solution of the RF battery and the battery characteristics will be specifically described with reference to test examples.

[Test Example 1]
A positive electrode electrolyte containing manganese ions and a negative electrode electrolyte containing titanium ions were prepared, the RF battery system shown in FIG. 1 was constructed, and after charging, the deposition state was examined.

  In this test, Sample No. containing only manganese ions as the positive electrode active material was used. Sample No. 1-100 containing manganese ions and vanadium ions (reactive metal ions) as positive electrode active materials. 1-1 were prepared.

  Sample No. The positive electrode electrolyte 1-1 was prepared using manganese sulfate, vanadium oxosulfate, and sulfuric acid (in this case, an aqueous solution). The produced positive electrode electrolyte has a manganese ion (divalent) concentration of 0.5 M, a vanadium ion (tetravalent) concentration of 0.5 M, and a sulfate ion concentration (the total concentration in the electrolyte, which is shown as the total concentration in the table) The same applies to the following test examples.) Is 4.0M.

  Sample No. A positive electrode electrolyte of 1-100 was prepared using manganese sulfate and sulfuric acid (here, an aqueous solution). The prepared positive electrode electrolyte has a manganese ion (divalent) concentration of 0.5M and a sulfate ion concentration (total concentration) of 3.5M.

  Sample No. 1-1, no. In any of 1-100, the negative electrode electrolyte was prepared using titanium sulfate and sulfuric acid (in this case, an aqueous solution). The produced negative electrode electrolyte has a titanium ion (tetravalent) concentration of 1.0 M and a sulfate ion concentration (total concentration) of 4.0 M.

A small cell having an electrode reaction area of 9 cm ² was produced. Carbon felt was used for each electrode, and an ion exchange membrane was used for the diaphragm.

7 ml of each prepared electrolyte solution was prepared, and charged using the prepared small cell. The charging conditions were a constant current of 630 mA (a constant current of 70 mA / cm ² ), and charging was performed until the state of charge (SOC) of manganese ions reached 70%. Immediately after this charging, the inner wall of the positive electrode electrolyte tank was visually confirmed. The state of charge (SOC,%) of manganese ions was determined by (charged electricity / theoretical electricity during one-electron reaction) × 100. In addition, the charge electricity amount and the theoretical electricity amount of one-electron reaction are expressed as follows. The one-electron reaction of manganese ions is Mn ²⁺ → Mn ³⁺ + e ⁻ .
Charged electricity (A · h) = Charging current (A) x Charging time (h)
Theoretical electricity of one-electron reaction (A · h) = electrolyte volume (L) × manganese ion concentration (mol / L) × Faraday constant: 96,485 (A · second / mol) × 1 (electron) / 3600

As a result, sample No. 1 containing only manganese ions in the positive electrode electrolyte was obtained. In 1-100, a brown substance (solid) was attached to the area where the cathode electrolyte was present on the inner wall of the tank of the cathode electrolyte. This brown material was analyzed and found to be MnO ₂ . From this, sample no. In 1-100, it turns out that a precipitate will generate | occur | produce when a charge condition is raised. On the other hand, sample No. In 1-1, the above deposits were not substantially seen on the inner wall of the positive electrode electrolyte tank. From this, it was confirmed that the generation of precipitates such as MnO ₂ can be suppressed by adding metal ions such as vanadium ions in addition to manganese ions to the positive electrode electrolyte.

[Test Example 2]
A positive electrode electrolyte containing manganese ions and a negative electrode electrolyte containing titanium ions were prepared, the RF battery system shown in FIG. 1 was constructed, and after charging, the state of charge (SOC) was examined.

  As the positive electrode electrolyte and the negative electrode electrolyte, those having the same ionic species and concentration as those in Test Example 1 were used. That is, sample no. 2-1 is an electrolytic solution having a composition of manganese ion (divalent) concentration of 0.5M, vanadium ion (tetravalent) concentration of 0.5M, and sulfate ion concentration (total concentration) of 4.0M as a positive electrode electrolytic solution. Prepared. Sample No. In No. 2-100, an electrolyte solution having a manganese ion (divalent) concentration of 0.5 M and a sulfate ion concentration (total concentration) of 3.5 M was prepared as a positive electrode electrolyte. In all the samples, an electrolyte solution having a composition of a negative electrode electrolyte having a titanium ion (tetravalent) concentration of 1.0 M and a sulfate ion concentration (total concentration) of 4.0 M was prepared. For each sample, 9 ml of the positive electrode electrolyte and 30 ml of the negative electrode electrolyte were prepared.

A small cell having an electrode reaction area of 9 cm ² was prepared and charged using the prepared electrolyte. The charging conditions were a constant current of 630 mA (a constant current with a current density of 70 mA / cm ² ), and a charge termination voltage of 2.0V. The state of charge (SOC,%) of manganese ions at the end of this charge was examined. The results are shown in Table 1. Further, after the end of charging, the amount of precipitates (here, MnO ₂ ) present in the tank or the like was visually examined. The results are shown in Table 1.

As shown in Table 1, sample No. 1 containing only manganese ions in the positive electrode electrolyte was used. Compared with 2-100, sample No. 2 containing metal ions such as vanadium ions in addition to manganese ions in the positive electrode electrolyte. 2-1, it can be seen that the state of charge (SOC) is higher. One of the reasons for the improved state of charge is that of sample no. In Example 2-1, it is considered that manganese ions were sufficiently utilized as an active material because generation of precipitates such as MnO ₂ could be suppressed by metal ions such as vanadium ions.

[Test Example 3]
A positive electrode electrolyte containing manganese ions and a negative electrode electrolyte containing titanium ions were prepared, the RF battery system shown in FIG. 1 was constructed, and the battery characteristics were examined by charging and discharging.

  As the positive electrode electrolyte and the negative electrode electrolyte, those having the same ionic species and concentration as those in Test Example 1 were used. That is, sample no. 3-1. As a positive electrode electrolyte, an electrolyte having a composition of manganese ion (divalent) concentration of 0.5M, vanadium ion (tetravalent) concentration of 0.5M, and sulfate ion concentration (total concentration) of 4.0M. Prepared. Sample No. 3-100 prepared an electrolyte solution having a composition of a manganese ion (divalent) concentration of 0.5 M and a sulfate ion concentration (total concentration) of 3.5 M as a positive electrode electrolyte. As a comparison, using titanium sulfate as a raw material, Sample No. 3 further containing titanium ions in the positive electrode electrolyte of 3-100. 3-110 was prepared. Sample No. The 3-110 positive electrode electrolyte is composed of an electrolyte having a composition of manganese ion (divalent) concentration of 0.5M, titanium ion (tetravalent) concentration of 0.5M, and sulfate ion concentration (total concentration) of 4.0M. did. In all the samples, an electrolyte solution having a composition of a negative electrode electrolyte having a titanium ion (tetravalent) concentration of 1.0 M and a sulfate ion concentration (total concentration) of 4.0 M was prepared. For each sample, 6 ml of electrolyte solution for each electrode was prepared.

A small cell having an electrode reaction area of 9 cm ² was prepared, and a charge / discharge cycle test was performed using the prepared electrolyte. The charging / discharging conditions are a constant current of 630 mA (constant current of 70 mA / cm ² current density), a charging side switching voltage (voltage switching from charging to discharging) is 1.5 V, and a discharging side switching voltage (from discharging to charging). The voltage to be switched) was 0 V, and the number of cycles was 3. Then, current efficiency (%) and discharge capacity (Ah / L) were examined. Here, the current efficiency (%) was obtained by (discharge time / charge time) × 100 for each cycle. Table 2 shows the average of the current efficiency at the second cycle and the current efficiency at the third cycle. For the discharge capacity, (discharge time (s) × current value (A) / 3600) / electrolyte volume (L) was determined for each cycle. Table 2 shows the average of the discharge capacity at the second cycle and the discharge capacity at the third cycle.

As shown in Table 2, sample No. 1 containing only manganese ions in the positive electrode electrolyte was used. Compared to 3-100, sample No. 1 containing metal ions such as vanadium ions in addition to manganese ions in the positive electrode electrolyte. 3-1, it turns out that current efficiency and discharge capacity are high. One of the reasons for the improvement in current efficiency and discharge capacity is that of sample no. In 3-1, it is considered that manganese ions could be sufficiently used as an active material because generation of precipitates such as MnO ₂ could be suppressed by metal ions such as vanadium ions. In addition to manganese ions, sample Nos. Containing metal ions such as vanadium ions. In Sample 3-1, sample No. 1 containing titanium ions in addition to manganese ions. It can be seen that the discharge capacity is improved as compared with 3-110. One of the reasons for the improved discharge capacity is that of sample no. In 3-1, it is thought that in addition to manganese ions, metal ions such as vanadium ions function as an active material, thereby increasing the energy density.

[Test Example 4]
A positive electrode electrolyte containing manganese ions and a negative electrode electrolyte containing titanium ions and manganese ions were prepared, the RF battery system shown in FIG. 1 was constructed, and the battery characteristics were examined by charging and discharging.

  The positive electrode electrolyte and the negative electrode electrolyte were prepared using sulfate and sulfuric acid as in Test Example 1. Sample No. 4-1 is an electrolytic solution having a composition of a manganese ion (divalent) concentration of 0.5M, a vanadium ion (tetravalent) concentration of 0.5M, and a sulfate ion concentration (total concentration) of 4.0M as a positive electrode electrolytic solution. 6 ml was prepared. As the negative electrode electrolyte, 12 ml of an electrolyte having a composition of titanium ion (tetravalent) concentration of 0.5M, manganese ion (divalent) concentration of 0.5M, and sulfate ion concentration (total concentration) of 4.0M was prepared.

  Sample No. 4-2 is a positive electrode electrolyte solution having a manganese ion (divalent) concentration of 0.5M, a vanadium ion (trivalent) concentration of 0.25M, a vanadium ion (tetravalent) concentration of 0.25M, and a sulfate ion concentration ( An electrolyte solution having a composition with a total concentration of 4.0M was prepared. The negative electrode electrolyte has a titanium ion (tetravalent) concentration of 0.5M, a manganese ion (divalent) concentration of 0.5M, a vanadium ion (trivalent) concentration of 0.25M, and a vanadium ion (tetravalent) concentration of 0. An electrolyte solution having a composition of .25M and a sulfate ion concentration (total concentration) of 4.5M was prepared. Sample No. In 4-2, 6 ml of electrolyte solution for each electrode was prepared.

Using the prepared electrolyte, a small cell similar to Test Example 3 (electrode reaction area 9 cm ² ) was prepared, a charge / discharge cycle test was performed, and current efficiency and discharge capacity were measured. The results are shown in Table 3. The charge / discharge conditions and measurement method are the same as in Test Example 3. However, sample No. For 4-2, the charge side switching voltage in the charge / discharge conditions was 1.85 V, and the discharge side switching voltage was 0 V.

  As shown in Table 3, sample No. 1 containing metal ions such as vanadium ions in addition to manganese ions in the positive electrode electrolyte. 4-1, no. It can be seen that 4-2 has a discharge capacity equivalent to that in the case where the positive electrode electrolyte contains only manganese ions. Sample No. 4-1, no. In 4-2, since the positive electrode electrolyte and the negative electrode electrolyte contain metal ions of the same ionic species, it is easy to suppress a decrease in the active material due to the movement of ions over time, or to correct the liquid transfer. It is easy to use because it is excellent in manufacturability. In this example, the metal ions of the same ionic species contained in the electrolyte solutions of both electrodes have the same valence and ion concentration, so that the above-described ease of correction of liquid transfer and ease of manufacture are superior.

  From the results of Test Examples 1 to 4, by containing manganese ions and specific metal ions (reactive metal ions) in the positive electrode electrolyte, the generation of precipitates such as manganese oxides can be suppressed. It was confirmed that a redox flow battery having excellent battery characteristics such as high electromotive force, increased charge state, increased current efficiency, and increased discharge capacity could be confirmed. In addition, since the redox flow battery has a high energy density and discharge capacity, the amount of the electrolytic solution can be reduced, so that downsizing and a reduction in electrolytic solution cost can be expected. Further, when a plurality of ionic species in the electrolyte solution of both electrodes overlap, the electrolyte solution is easy to correct the liquid transfer or to easily manufacture the electrolyte solution. By providing such an electrolytic solution, a redox flow battery that is practical and easy to perform operation control can be obtained.

  The redox flow battery of the present invention has a large capacity for the purpose of stabilizing fluctuations in power generation output, storing power when surplus generated power, load leveling, etc., for power generation of natural energy such as solar power generation and wind power generation. It can utilize suitably for this storage battery. The redox flow battery of the present invention can be suitably used as a large-capacity storage battery that is provided in a general power plant and is used for the purpose of instantaneous voltage drop / power failure countermeasures and load leveling.

DESCRIPTION OF SYMBOLS 1 Redox flow battery (RF battery) 100 Battery cell 101 Diaphragm 102 Positive electrode cell 103 Negative electrode cell 104 Positive electrode 105 Negative electrode 106 Tank for positive electrolyte 107 Tank for negative electrolyte 108-111 Conduit 112,113 Pump 200 AC / DC converter 210 Substation equipment 300 Power generation unit 400 Load

Claims (13)

A redox flow battery that performs charging and discharging by supplying a positive electrode electrolyte and a negative electrode electrolyte to a battery cell including a positive electrode, a negative electrode, and a diaphragm interposed between the two electrodes,
The positive electrode electrolyte contains manganese ions and reactive metal ions,
The negative electrode electrolyte contains at least one metal ion selected from titanium ions, chromium ions, and zinc ions,
The reactive metal ion is at least one selected from vanadium ion, chromium ion, iron ion, cobalt ion, copper ion, molybdenum ion, ruthenium ion, palladium ion, silver ion, tungsten ion, mercury ion and cerium ion. Redox flow battery. The positive electrode electrolyte further contains an additive metal ion,
2. The redox flow battery according to claim 1, wherein the additive metal ion is at least one selected from aluminum ion, cadmium ion, indium ion, tin ion, antimony ion, iridium ion, gold ion, lead ion, and bismuth ion. .   The redox flow battery according to claim 1 or 2, wherein a concentration of the reactive metal ion in the positive electrode electrolyte is 0.001M or more and 5M or less.   The redox flow battery according to claim 2, wherein the concentration of the added metal ion in the positive electrode electrolyte is 0.001 M or more and 1 M or less.   5. The concentration according to claim 1, wherein at least one of the manganese ion concentration in the positive electrode electrolyte and the metal ion concentration in the negative electrode electrolyte is 0.3 M or more and 5 M or less. Redox flow battery. The negative electrode electrolyte contains titanium ions as the metal ions,
6. The device according to claim 1, wherein at least one of the manganese ion concentration in the positive electrode electrolyte and the titanium ion concentration in the negative electrode electrolyte is 0.3 M or more and 5 M or less. Redox flow battery. The redox flow battery according to any one of claims 1 to 6, wherein the reactive metal ion satisfies at least one of the following (A) to (L).
(A) The vanadium ion is a divalent vanadium ion, a trivalent vanadium ion, a tetravalent vanadium ion, or a pentavalent vanadium ion. (B) The chromium ion is a divalent chromium ion, 3 (C) the iron ion is at least one of a divalent iron ion and a trivalent iron ion. (D) the valent chromium ion, a tetravalent chromium ion, and a hexavalent chromium ion. The cobalt ion is at least one of a divalent cobalt ion and a trivalent cobalt ion. (E) The copper ion is at least one of a monovalent copper ion and a divalent copper ion. (F) The molybdenum ion. Is at least one of tetravalent molybdenum ions, pentavalent molybdenum ions, and hexavalent molybdenum ions. (G) The mu ion is at least one of divalent ruthenium ion, trivalent ruthenium ion, and tetravalent ruthenium ion. (H) The palladium ion is at least one of divalent palladium ion and tetravalent palladium ion. I) The silver ion is at least one of monovalent silver ion and divalent silver ion. (J) The tungsten ion is at least tetravalent tungsten ion, pentavalent tungsten ion, and hexavalent tungsten ion. (K) The mercury ion is at least one of monovalent mercury ion and divalent mercury ion. (L) The cerium ion is at least one of trivalent cerium ion and tetravalent cerium ion. is there   The redox flow battery according to any one of claims 1 to 7, wherein the negative electrode electrolyte further contains manganese ions.   The redox flow battery according to any one of claims 1 to 7, wherein the negative electrode electrolyte further contains manganese ions and the reactive metal ions.   5. The redox flow battery according to claim 2, wherein the negative electrode electrolyte further contains manganese ions, the reactive metal ions, and the additive metal ions.   The redox flow battery according to any one of claims 8 to 10, wherein a concentration of manganese ions in the negative electrode electrolyte is 0.3 M or more and 5 M or less. 11. The redox flow battery according to claim 2, wherein the additive metal ion satisfies at least one of the following (a) to (i):
(A) The aluminum ion is a monovalent aluminum ion, a divalent aluminum ion, or a trivalent aluminum ion. (B) The cadmium ion is a monovalent cadmium ion or a divalent cadmium ion. (C) The indium ion is at least one of monovalent indium ion, divalent indium ion, and trivalent indium ion. (D) The tin ion is divalent tin ion and tetravalent. (E) the antimony ion is a trivalent antimony ion and at least one of a pentavalent antimony ion (f) the iridium ion is a monovalent iridium ion or a divalent iridium ion Trivalent iridium ion, tetravalent iridium ion, pentavalent iri (G) The gold ion is a monovalent gold ion, a divalent gold ion, a trivalent gold ion, a tetravalent gold ion, or a pentavalent gold ion. (H) The lead ion is at least one of a divalent lead ion and a tetravalent lead ion. (I) The bismuth ion is at least a trivalent bismuth ion and a pentavalent bismuth ion. On the other hand The manganese ion is at least one of a divalent manganese ion and a trivalent manganese ion;
The negative electrode electrolyte solution contains titanium ions as the metal ions, and the titanium ions are at least one of trivalent titanium ions and tetravalent titanium ions. The redox flow battery described.

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