Abstract: Redox flow battery systems are described. The redox flow battery systems include a main cell and a three-chambered rebalancing cell. The system can optionally also include a two-chambered rebalancing cell. The three-chambered rebalancing cell and two-chambered rebalancing cell can be operated alternately, in parallel, or in series. Methods of operating the redox flow battery systems are also described.

Abstract: Processes for limiting circulation of precipitates in a redox flow battery system are described. The processes include filtering the negative electrolyte, or the positive electrolyte, or both in one or more filters. The filter(s) can be located in the negative electrolyte loop, the positive electrolyte loop, or in both loops. Filtering can take place in normal operation; it can also take place during refresh cycles.

Abstract: Devices and methods for managing the state of health of an electrolyte in redox flow batteries (RFB) efficiently are described. A diffusion cell is added to the RFB which controls one or more properties of the electrolytes using the diffusion of protons through a proton exchange membrane. The diffusion cell can resemble an electrochemical cell in that there are two fluid chambers divided by a proton conducting membrane. Anolyte flows through one side of the device where it contacts the proton conducting membrane, and catholyte flows through the second side of the device where it contacts the other face of the proton conducting membrane. The concentration gradient of protons from high concentration in the catholyte to low concentration in the anolyte is the driving force for proton diffusion, rather than electromotive force, which greatly simplifies the design and operation.

Abstract: Devices and methods for managing the state of health of an electrolyte in redox flow batteries (RFB) efficiently are described. A diffusion cell is added to the RFB which controls one or more properties of the electrolytes using the diffusion of protons through a proton exchange membrane. The diffusion cell can resemble an electrochemical cell in that there are two fluid chambers divided by a proton conducting membrane. Anolyte flows through one side of the device where it contacts the proton conducting membrane, and catholyte flows through the second side of the device where it contacts the other face of the proton conducting membrane. The concentration gradient of protons from high concentration in the catholyte to low concentration in the anolyte is the driving force for proton diffusion, rather than electromotive force, which greatly simplifies the design and operation.