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Title: Systems and methods for rebalancing redox flow battery electrolytes

Abstract

Various methods of rebalancing electrolytes in a redox flow battery system include various systems using a catalyzed hydrogen rebalance cell configured to minimize the risk of dissolved catalyst negatively affecting flow battery performance. Some systems described herein reduce the chance of catalyst contamination of RFB electrolytes by employing a mediator solution to eliminate direct contact between the catalyzed membrane and the RFB electrolyte. Other methods use a rebalance cell chemistry that maintains the catalyzed electrode at a potential low enough to prevent the catalyst from dissolving.

Inventors:
;
Publication Date:
Research Org.:
Enervault Corporation, Sunnyvale, CA (United States)
Sponsoring Org.:
USDOE
OSTI Identifier:
1172757
Patent Number(s):
8,980,454
Application Number:
14/207,795
Assignee:
Enervault Corporation (Sunnyvale, CA) NETL
DOE Contract Number:
OE0000225
Resource Type:
Patent
Resource Relation:
Patent File Date: 2014 Mar 13
Country of Publication:
United States
Language:
English
Subject:
25 ENERGY STORAGE

Citation Formats

Pham, Ai Quoc, and Chang, On Kok. Systems and methods for rebalancing redox flow battery electrolytes. United States: N. p., 2015. Web.
Pham, Ai Quoc, & Chang, On Kok. Systems and methods for rebalancing redox flow battery electrolytes. United States.
Pham, Ai Quoc, and Chang, On Kok. 2015. "Systems and methods for rebalancing redox flow battery electrolytes". United States. doi:. https://www.osti.gov/servlets/purl/1172757.
@article{osti_1172757,
title = {Systems and methods for rebalancing redox flow battery electrolytes},
author = {Pham, Ai Quoc and Chang, On Kok},
abstractNote = {Various methods of rebalancing electrolytes in a redox flow battery system include various systems using a catalyzed hydrogen rebalance cell configured to minimize the risk of dissolved catalyst negatively affecting flow battery performance. Some systems described herein reduce the chance of catalyst contamination of RFB electrolytes by employing a mediator solution to eliminate direct contact between the catalyzed membrane and the RFB electrolyte. Other methods use a rebalance cell chemistry that maintains the catalyzed electrode at a potential low enough to prevent the catalyst from dissolving.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = 2015,
month = 3
}

Patent:

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  • Embodiments of redox flow battery rebalancing systems include a system for reacting an unbalanced flow battery electrolyte with a rebalance electrolyte in a first reaction cell. In some embodiments, the rebalance electrolyte may contain ferrous iron (Fe.sup.2+) which may be oxidized to ferric iron (Fe.sup.3+) in the first reaction cell. The reducing ability of the rebalance reactant may be restored in a second rebalance cell that is configured to reduce the ferric iron in the rebalance electrolyte back into ferrous iron through a reaction with metallic iron.
  • An aqueous redox flow battery system includes an aqueous catholyte and an aqueous anolyte. The aqueous catholyte may comprise (i) an optionally substituted thiourea or a nitroxyl radical compound and (ii) a catholyte aqueous supporting solution. The aqueous anolyte may comprise (i) metal cations or a viologen compound and (ii) an anolyte aqueous supporting solution. The catholyte aqueous supporting solution and the anolyte aqueous supporting solution independently may comprise (i) a proton source, (ii) a halide source, or (iii) a proton source and a halide source.
  • There is disclosed an electrically rechargeable REDOX cell or battery system including one or more rebalancing cells. Each rebalancing cell is divided into two chambers by an ion permeable membrane. The first chamber is fed with gaseous hydrogen and a cathode fluid which is circulated through the cathode chamber of the REDOX cell is also passed through the second chamber of the rebalancing cell. Electrochemical reactions take place on the surface of inert electrodes in the first and second chambers to rebalance the electrochemical capacity of the anode and cathode fluids of the REDOX system.
  • A reduction/oxidation ("redox") flow battery system includes a series of electrochemical cells arranged in a cascade, whereby liquid electrolyte reacts in a first electrochemical cell (or group of cells) before being directed into a second cell (or group of cells) where it reacts before being directed to subsequent cells. The cascade includes 2 to n stages, each stage having one or more electrochemical cells. During a charge reaction, electrolyte entering a first stage will have a lower state-of-charge than electrolyte entering the nth stage. In some embodiments, cell components and/or characteristics may be configured based on a state-of-charge of electrolytesmore » expected at each cascade stage. Such engineered cascades provide redox flow battery systems with higher energy efficiency over a broader range of current density than prior art arrangements.« less
  • Methods, systems and structures for monitoring, managing electrolyte concentrations in redox flow batteries are provided by introducing a first quantity of a liquid electrolyte into a first chamber of a test cell and introducing a second quantity of the liquid electrolyte into a second chamber of the test cell. The method further provides for measuring a voltage of the test cell, measuring an elapsed time from the test cell reaching a first voltage until the test cell reaches a second voltage; and determining a degree of imbalance of the liquid electrolyte based on the elapsed time.