Abstract: Methods of determining concentrations and/or amounts of redox-active elements at each valence state in an electrolyte solution of a redox flow battery are provided. Once determined, the concentrations and/or amounts of the redox-active elements at each valence state can be used to determine side-reactions, make chemical adjustments, periodically monitor battery capacity, adjust performance, or to otherwise determine a baseline concentration of the redox-active ions for any purpose.

Abstract: A redox flow battery includes an anolyte storage tank having a height configured for containing a quantity of an anolyte; a catholyte storage tank having a height configured for containing a quantity of a catholyte; an electrochemical cell configured for fluid communication with the anolyte and catholyte storage tanks; and a tub defining a cavity formed in at least one of the anolyte and catholyte storage tanks to provide a sealed fluid connection point below the height of the at least one storage tank.

Abstract: A redox flow battery includes an anolyte storage tank configured for containing a quantity of anolyte and an anolyte headspace; a catholyte storage tank configured for containing a quantity of a catholyte and a catholyte headspace; and a gas management system comprising at least one conduit interconnecting the anolyte headspace and the catholyte headspace, and a gas exchange device configured to contain or release an evolving gas from either or both of the anolyte and catholyte storage tanks to an exterior battery environment when an interior battery pressure exceeds an exterior battery pressure by a predetermined amount.

Abstract: A redox flow battery (RFB) controllable by a battery management system and having an energy output has a volume of at least 2000 liters and an energy density of at least 10 w-h/liter. In one embodiment, the RFB maintains at an energy density of at least 10 w-h/liter for a minimum of 50 continuous full charge/discharge cycles or the equivalent number of operating hours without user input.

Abstract: A redox flow battery includes a battery housed in a substantially closed housing having at least first and second internal containers, wherein the first and second containers are in fluid communication with each other, and wherein the first container is configured for containing a quantity of electrolyte and providing a gas headspace above the electrolyte; an electrolyte circulation system configured to circulate the electrolyte between the first and second containers; and -an anti-siphon device configured to prevent siphoning between the first and second containers.

Abstract: A method of operating an all vanadium redox flow battery includes providing an all vanadium redox flow battery comprising an anolyte storage tank including a volume of anolyte and a catholyte storage tank including a volume of catholyte; an electrochemical cell in fluid communication with the anolyte and catholyte storage tanks; and a predetermined range for the ratio of vanadium concentration between the anolyte and the catholyte; and transferring an amount of catholyte from the catholyte storage tank to the anolyte storage tank, or an amount of anolyte from the anolyte storage tank to the catholyte storage tank, to restore the ratio of vanadium concentration to the predetermined range. An all vanadium redox flow battery system includes means for transferring anolyte and catholyte between the anolyte and catholyte storage tanks to maintain a predetermined range for the ratio of vanadium concentration between the anolyte and the catholyte.

Abstract: Methods of determining concentrations and/or amounts of redox-active elements at each valence state in an electrolyte solution of a redox flow battery are provided. Once determined, the concentrations and/or amounts of the redox-active elements at each valence state can be used to determine side-reactions, make chemical adjustments, periodically monitor battery capacity, adjust performance, or to otherwise determine a baseline concentration of the redox-active ions for any purpose.

Abstract: Disclosed herein are improved electrochemical cell stacks having at least one protective channel on an end of the stack. Redox flow batteries (RFBs) containing the “protected” electrochemical cell stacks, and methods of operating such RFBs, are also provided.

Abstract: A barrier on the surface of the negative electrolyte solution of a redox flow battery can decrease air oxidation of a charged species in the negative electrolyte solution and can decrease water loss from the negative electrolyte solution. A negative electrolyte tank including a barrier on the surface of the negative electrolyte can have many advantages, including simplified setup, low cost, and low maintenance.