A method for determining an average oxidation state (AOS) of a redox flow battery system includes measuring a charge capacity for a low potential charging period starting from a discharged state of the redox flow battery system to a turning point of a charge voltage; and determining the AOS using the measured charge capacity and volumes of anolyte and catholyte of the redox flow battery system. Other methods can be used to determine the AOS for a redox flow battery system or use discharge voltage instead of charging voltage.

A redox flow battery includes a cathode, an anode, a charge-carrying electrolyte, and an (a) oxidized and a (b) reduced form of an active material. The active material has the following formula: (D)-(L)-(A)-[(L)-(A)].sub.V-D.sub.Z(F1) or (D)-(L)-(A)-(L-D).sub.X (F2). In these formulae, each D is covalently bonded to an L, each L is covalently bonded to an A, x is a number from 0 to 5, v is a number from 0 to 5 and z is 0 or 1. D is an electron donor compound, L is a linker, and A is an electron acceptor compound. Each of D, L, and A has a particular structure.

Systems and methods for managing flow batteries utilize a battery management controller (BMC) coupled between a flow battery and a DC/DC converter, which is coupled to an electrical grid or a photovoltaic device via an inverter. The inverter converts an AC voltage to a first DC voltage and the DC/DC converter steps down the first DC voltage to a second DC voltage. The BMC includes a first power route, a second power route, and a current source converter coupled to the second power route. The BMC initializes the flow battery with a third DC voltage using the current source converter until a sensing circuit senses that the voltage of the flow battery has reached a predetermined voltage. The sensing circuit may include a capacitor, which has a small capacitance and is coupled across each cell of the flow battery, coupled in series between two resistors having very large resistances.

The present invention relates to novel combinations of redox active compounds for use as redox flow battery electrolytes. The invention further provides kits comprising these combinations, redox flow batteries, and method using the combinations, kits and redox flow batteries of the invention.

The present disclosure discloses a stable and high-capacity neutral aqueous redox flow lithium battery based on redox-targeting reaction and belongs to the technical field of flow lithium batteries. The present disclosure solves the technical problem that an existing flow battery can only work at low current density. The flow lithium battery of the present disclosure includes a positive electrode storage tank and a negative electrode storage tank; the positive electrode storage tank is filled with a positive electrolyte; and the negative electrode storage tank is filled with a negative electrolyte. The flow lithium battery is characterized in that the positive electrolyte includes a salt containing [Fe(CN).sub.6].sup.4− and/or [Fe(CN).sub.6].sup.3−, and the positive electrode storage tank is further filled with LFP particles and/or FP particles. The flow lithium battery of the present disclosure has wide application prospects in the field of large-scale energy storage.

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.

Multi-phase electrochemical cells and related systems and methods are generally described.

A redox flow battery system includes an anolyte having a first ionic species in solution; a catholyte having a second ionic species in solution, where the redox flow battery system is configured to reduce the first ionic species in the anolyte and oxidize the second ionic species in the catholyte during charging; a first electrode in contact with the anolyte, where the first electrode includes channels for collection of particles of reduced metallic impurities in the anolyte; a second electrode in contact with the catholyte; and a separator separating the anolyte from the catholyte. A method of reducing metallic impurities in an anolyte of a redox flow battery system includes reducing the metallic impurities in the anolyte; collecting particles of the reduced metallic impurities; and removing the collected particles using a cleaning solution.

An organic positive electrode active material for aqueous redox flow batteries, and more particularly, to technology of applying an organic positive electrode active material to make up for the drawbacks of conventional aqueous redox flow batteries. An aqueous redox flow battery to which a particular positive electrode active material is applied has no problems regarding metal deposition, and can also be useful in realizing a high energy density because the positive electrode active material may be used at high concentration due to an increase in solubility in a solvent, attaining a high working voltage, and enhancing energy efficiency. Also, the aqueous redox flow battery has excellent economic feasibility because an expensive organic electrolyte is not used.

A molten metal battery system includes a plurality of secondary cells electrically connected in series with each other and comprising a plurality of molten metal anodes arranged fluidly in parallel with each other. The system also includes a plurality of electrically isolated molten metal reservoirs, each of the molten metal reservoirs fluidly connected to a corresponding secondary cell of the plurality of secondary cells and configured to exchange molten metal with the corresponding secondary cell while preventing electrical shunt current from flowing between the plurality of secondary cells via the molten metal.