Loss of flow battery electrode catalyst layers during self-discharge or charge reversal may be prevented by establishing and maintaining a negative electrolyte imbalance during at least parts of a flow battery's operation. Negative imbalance may be established and/or maintained actively, passively or both. Actively establishing a negative imbalance may involve detecting an imbalance that is less negative than a desired threshold, and processing one or both electrolytes until the imbalance reaches a desired negative level. Negative imbalance may be effectively established and maintained passively within a cell by constructing a cell with a negative electrode chamber that is larger than the cell's positive electrode chamber, thereby providing a larger quantity of negative electrolyte for reaction with positive electrolyte.
STATEMENT OF FEDERALLY FUNDED RESEARCH
 Inventions included in this patent application were made with Government support under DE-0E0000225 "Recovery Act--Flow Battery Solution for Smart Grid Renewable Energy Applications" awarded by the U.S. Department of Energy (DOE). The Government has certain rights in these inventions.