Pathways to High-Power-Density Redox Flow Batteries

Abstract

Redox flow batteries (RFBs) promise to fill a crucial missing link in the energy transition: inexpensive and widely deployable grid and industrial-scale energy storage for intermittent renewable electricity. While numerous lab-scale and demonstration-scale RFBs have been delivered, widespread commercial deployment is still limited by high electrolyte, stack, and balance of plant capital costs. Increasing the power density of RFBs is correlated with lower stack costs, primarily because the area needed for expensive electrode and membrane components to reach a target power density is reduced. In the present contribution, we summarize the areal power densities reported for lab-scale RFBs, critically evaluate major pathways employed for power optimization, and identify opportunities for developing yet-higher power density systems.

Electrochemical Performance of Mixed Redox-Active Organic Molecules in Redox Flow Batteries

“…Redox flow batteries (RFBs) are attractive technologies with a unique architecture that has showed promise for large-scale energy storage applications. 3 In RFBs, in which the electrolyte containing the redox active species is stored in external tanks and is continuously pumped to the electrochemical cell stack, the stack (power component) and the electrolyte (energy capacity component) can be independently and flexibly designed and scaled up. 4 Among different types of RFBs, aqueous organic-based RFBs have gained a lot of attention due to the possibility of tuning their properties by modifying their molecular structures.…”

Long-term performance of hydrogen-bromine flow batteries using single-layered and multi-layered wire-electrospun SPEEK/PFSA/PVDF membranes

“…1 However, the inherent intermittency of renewable energy sources, such as solar and wind power, accentuates an imperative need for dependable, efficient, and economically viable energy storage technologies. 2 In the domain of electrochemical systems, redox ow batteries (RFBs) stand out as an environmentally friendly resource, seamlessly integrating swi reaction time coupled with remarkable efficiency. 3,4 Promisingly addressing the exibility of RFBs, hydrogen-bromine ow batteries (HBFBs) offer the potential for high power output alongside cost-effectiveness.…”

“…1 However, the inherent intermittency of renewable energy sources, such as solar and wind power, accentuates an imperative need for dependable, efficient, and economically viable energy storage technologies. 2…”

A Redox Tale of Two Phosphine Oxides (and a Terthiophene)

“…For instance, whereas high volumetric capacities can, in principle, be achieved in nonaqueous RFBs using high-solubility electrolytes, the concomitant increases in solvent viscosity and resistivity hamper electrolyte pumping and typically lead to low power densities in actual flow cells. 32 In this regard, the development of low-potential, multielectron electrolytes 19 30 such as functionalized terthiophenes 23 could help to achieve high capacities without the need to employ excessively high electrolyte concentrations. Finally, addressing issues relating to electrolyte crossover and low ionic conductivity will also be key to the realization of nonaqueous RFBs with high power densities.…”