A redox flow battery includes first and second cells. Each cell has electrodes and a separator layer arranged between the electrodes. A first circulation loop is fluidly connected with the first electrode of the first cell. A polysulfide electrolyte solution has a pH 11.5 or greater and is contained in the first recirculation loop. A second circulation loop is fluidly connected with the second electrode of the second cell. An iron electrolyte solution has a pH 3 or less and is contained in the second circulation loop. A third circulation loop is fluidly connected with the second electrode of the first cell and the first electrode of the second cell. An intermediator electrolyte solution is contained in the third circulation loop. The cells are operable to undergo reversible reactions to store input electrical energy upon charging and discharge the stored electrical energy upon discharging.

The provided are an electrolyte for redox flow battery and a redox flow battery comprising the same, wherein the electrolyte for redox flow battery comprises a solute and a solvent, wherein said solute comprises at least one of anode active material and cathode active material, wherein said anode active material comprises at least one of organic compounds having a carbonyl group such as benzophenone-, benzoquinone-, dimethyl terephthalate-, and 1,4-diacetylbenzene-based organic compounds, and said cathode active material comprises at least one of amine-, tetrathiafulvalene-, and N,N,N′,N′-tetramethyl-p-phenylenediamine-based organic compounds.

Methods and systems are provided for a redox flow battery system. In one example, the redox flow battery is adapted with an additive included in a battery electrolyte and an anion exchange membrane separator dividing positive electrolyte from negative electrolyte. An overall system cost of the battery system may be reduced while a storage capacity, energy density and performance may be increased.

Flow batteries can include a first half-cell containing a first aqueous electrolyte solution, a second half-cell containing a second aqueous electrolyte solution, and a separator disposed between the first half-cell and the second half-cell, The first aqueous electrolyte solution contains a first redox-active material, and the second aqueous electrolyte solution contains a second redox-active material. At least one of the first redox-active material and the second redox-active material is a nitroxide compound or a salt thereof. Particular nitroxide compounds can include a doubly bonded oxygen contained in a ring bearing the nitroxide group, a doubly bonded oxygen appended to a ring bearing the nitroxide group, sulfate or phosphate groups appended to a ring bearing the nitroxide group, various heterocyclic rings bearing the nitroxide group, or acyclic nitroxide compounds.

The hybrid battery system has multiple discharge voltage plateaus and a greater charge capacity of metal in the negative electrode, while still having sufficient energy density and sufficient power capability to supply external devices. The charge capacity of the negative side is higher than the charge capacity of the positive side. There are two solvent compositions in the cathodic solution, and there is a transition from a first discharge voltage plateau to a second discharge voltage plateau at a voltage less than the first discharge voltage plateau. The battery system is safe, and the transition between discharge voltage plateaus provides an estimation of battery capacity that can indicate when the battery system is running out of power.

An electrochemical apparatus includes a catholyte, an anolyte, and a separator disposed between the catholyte and the anolyte. The catholyte includes metal salt dissolved in water, thereby providing at least one metal ion. The anolyte includes a polysulfide solution. The separator is permeable to the at least one metal ion. During a charging process of the electrochemical apparatus, oxygen is generated in the catholyte, the polysulfide in the polysulfide solution undergoes a reduction reaction in the anolyte, and the at least one metal ion moves from the catholyte to the anolyte. During a discharging process of the apparatus, the oxygen is consumed in the catholyte, the polysulfide oxidizes in the anolyte, and the at least one metal ion moves from the anolyte to the catholyte.

A redox flow battery (1) that is charged and discharged by circulation of an electrolyte, which contains vanadium as an active material, in a battery cell (2) including a positive electrode (10), a negative electrode (20), and a membrane (30) interposed between the electrodes (10) and (20), wherein: at least the positive electrode (10) or the negative electrode (20) contains carbon nanotubes the average diameter of which is 150 nm or smaller; and the porosity of the negative electrode 20 is higher than the porosity of the positive electrode.

The present disclosure is directed to triblock copolymer based anion exchange membranes (AEMs) and methods for making same. The membranes are useful as separators in electrochemical devices, such as fuel cells, electrolyzers, water desalination systems, and redox flow batteries.

Flow batteries can include a first half-cell containing a first aqueous electrolyte solution, a second half-cell containing a second aqueous electrolyte solution, and a separator disposed between the first half-cell and the second half-cell. The first aqueous electrolyte solution contains a first redox-active material, and the second aqueous electrolyte solution contains a second redox-active material. At least one of the first redox-active material and the second redox-active material is a nitroxide compound or a salt thereof. Particular nitroxide compounds can include a doubly bonded oxygen contained in a ring bearing the nitroxide group, a doubly bonded oxygen appended to a ring bearing the nitroxide group, sulfate or phosphate groups appended to a ring bearing the nitroxide group, various heterocyclic rings bearing the nitroxide group, or acyclic nitroxide compounds.

The present invention discloses a rechargeable tin-iodate battery, including static battery and redox flow battery, in which anodic tin will be dissolved as Sn.sup.2+ and Sn.sup.4+ ions while iodate will be reduced to iodine and iodide at carbon cathode during discharging. The process will be reversed in charging. The tin-iodate battery comprises a tin anode (1), a carbon cathode (2), a selective permeable separator (3), and aqueous acidic electrolytes, whereby electricity energy can stored with high energy density and high power density, and large-scale energy storage and electrified vehicle can be achieved.