The project MFreeB (Membrane-Free Redox Flow Batteries) proposes a disruptive, versatile and scalable redox flow battery in which the currently used vanadium pairs are replaced by cheap, abundant and environmental-friendly organic molecules and where the problematic ion-exchange membrane that serves as electrolyte separator is totally eliminated due to the development of new and immiscible redox electrolytes. New thermodynamic, fluid-dynamic and engineering aspects, never considered before in energy storage, will become key players in the development of this technology that constitutes a paradigm shift in energy storage.
One of the main barriers for worldwide deployment of energy storage systems coupled to renewable generation plants and power distribution systems is related to their high investment cost. Membrane-Free RFBs using organic couples may lead to investment costs clearly below the US DoE’s threshold (150 $/kWh) because they will spare the cost of membranes, will make use of low cost organic compounds and will not need expensive materials to stand highly corrosive environments. Additionally, Membrane-Free batteries will not require membrane cleaning and substitution, or electrolyte re-balance due to crossover after prolonged use, thus making operation and maintenance significantly simpler and more appropriate for domestic applications. Based on these features, Membrane-Free batteries proposed in this ERC project may boost the market of redox flow batteries for stationary energy storage applications.