Electrostatically driven unidirectional molecular flux for high performance alkaline flow batteries.

To mitigate the mismatch between energy availability and energy demand due to day/night shifts and seasonal variations, intensive efforts have been dedicated to storing renewable energy in various energy storage modules. Redox flow batteries have an upper hand over conventional batteries as energy storage modules due to their capability of decoupling energy and power. However, interfacial events, such as mass transport and electron transfer, play pivotal roles in flow batteries' energy storage and conversion mechanisms. We show that by activating electrostatic forces at the interface, unidirectional molecular flux can be achieved to and from the driving electrode surface, thereby generating a parallel or antiparallel electrostatic current along with a diffusion current. This approach of triggering electrostatic forces in flow batteries enhances their volumetric energy density and amplifies the energy efficiency to values as high as ∼92% without altering the solubility limit of the redox active species.