Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: Methods and apparatuses are disclosed for mitigating electrolyte migration in a redox flow battery system. A first parameter of a first electrolyte in a first flow path of a redox flow battery cell block may be measured. The first flow path may have an inlet to and an outlet from the redox flow battery cell block. A second parameter of a second electrolyte in a second flow path of the redox flow battery cell block may be measured. The second flow path may have an inlet to and an outlet from the redox flow battery cell block. The first parameter may be detected to be greater than the second parameter. A first device coupled to the redox flow battery cell block in the second flow path may be operated to increase the second parameter in the second flow path.

Abstract: A redox flow battery system is provided with independent stack assemblies dedicated for charging and discharging functions. In such a system, characteristics of the charging stack assembly may be configured to provide a high efficiency during a charging reaction, and the discharging stack may be configured to provide a high efficiency during a discharging reaction. In addition to decoupling charging and discharging reactions, redox flow battery stack assemblies are also configured for other variables, such as the degree of power variability of a source or a load. Using a modular approach to building a flow battery system by separating charging functions from discharging functions, and configuring stack assemblies for other variables, provides large-scale energy storage systems with great flexibility for a wide range of applications.