Hybrid Organic and Inorganic Redox Active Components for Non-Aqueous Redox Flow Batteries

Abstract

Redox flow battery (RFB), as one of the most promising technologies for large-scale stationary energy storage up to MW (power) or MWh (energy), has attracted increasingly attentions from both academic and industrial research groups.1RFB is characteristic of many attractive advantages including decoupling of energy storage and power output, exceptional design flexibility, excellent scalability and modularity, long service life, high efficiency, etc. These technic merits makeRFB a well-suitable choice to stabilize the power grid and overcome the intermittency of renewable energy sources (solar, wind and hydroelectricity etc.).2 Traditional aqueous RFB (ARFB), although with a number of technic advantages, is primarily limited by low energy density due to the narrow operation voltage confined by water electrolysis and low concentrations of redox components. To circumvent the limitations of the ARFB system, we have initiated research on non-aqueous redox flow battery (NARFB) employing redox active organic3and hybrid organic/inorganic molecules as flowable electrode materials.In this presentation, we will report our new results on synthetically design and modification of advanced redox active organometallic complexes in order to optimize operating redox potentials and increase concentrations (i.e. volumetric energy density). Electrochemical performance of the new electrode materials for NARFB will be discussed to highlight research and development of NARFB at PNNL and address future research directions.