US 11,955,678 B2
Method to improved redox flow battery performance
Chunqing Liu, Arlington Heights, IL (US); Chaoyi Ba, Schaumburg, IL (US); and Xueliang Dong, Schaumburg, IL (US)
Assigned to UOP LLC, Des Plaines, IL (US)
Filed by UOP LLC, Des Plaines, IL (US)
Filed on Sep. 14, 2021, as Appl. No. 17/474,200.
Prior Publication US 2023/0085103 A1, Mar. 16, 2023
Int. Cl. H01M 8/18 (2006.01); H01M 4/86 (2006.01); H01M 4/88 (2006.01)
CPC H01M 8/188 (2013.01) [H01M 4/8657 (2013.01); H01M 4/8853 (2013.01); H01M 8/18 (2013.01); H01M 2004/8684 (2013.01); H01M 2300/0002 (2013.01)] 17 Claims
OG exemplary drawing
 
1. A method of pre-plating a negative electrode of a redox flow battery system in-situ before operating the redox flow battery system comprising:
pre-charging the redox flow battery system to pre-plate metal on a negative electrode of the redox flow battery system from a negative electrolyte of the redox flow battery system, the redox flow battery system comprising at least one rechargeable cell comprising a positive electrolyte, the negative electrolyte, and a membrane positioned between the positive electrolyte and the negative electrolyte, the positive electrolyte in contact with a positive electrode, the negative electrolyte in contact with the negative electrode, an external positive electrolyte storage tank comprising the positive electrolyte, a positive electrolyte circulation pump in fluid communication with the positive electrolyte of the at least one rechargeable cell and the external positive electrolyte storage tank, an external negative electrolyte storage tank comprising the negative electrolyte, a negative electrolyte circulation pump in fluid communication with the negative electrolyte of the at least one rechargeable cell and the external negative electrolyte storage tank, wherein the negative electrolyte comprises metal ions before and after metal pre-plating, and wherein the negative electrolyte and the positive electrolyte are circulating during the metal pre-plating;
wherein the redox flow battery system is an all-iron redox flow battery system and the metal pre-plated on the negative electrode is Fe(O), wherein the negative electrolyte comprises Fe2+ before and after the Fe(O) pre plating, and wherein the positive electrolyte comprises Fe2+ before the Fe(O) pre-plating and comprises Fe2+ and Fe3+ after the Fe(O) pre-plating, and wherein the redox flow battery system is pre-charged at a current density in a range of 2 mA/cm2 to 40 mA/cm2 for 4 h to 120 h to pre-plate the Fe(O) on the negative electrode of the redox flow battery system;
reducing the Fe3+ to Fe2+ in the positive electrolyte using a hydrogen recombination reactor; adjusting a concentration of the Fe2+ in the negative electrolyte to a final concentration after pre-charging the redox flow battery system and before initiating a charging/discharging cycle; and initiating at least one charging/discharging cycle.