Cost-Effective, High-Energy-Density, Nonaqueous Nitrobenzene Organic Redox Flow Battery

Nonaqueous organic redox flow batteries (NAORFBs) show great promise for grid energy storage but are currently facing key challenges such as high electroactive material cost and low energy density. Herein, we report the electrochemical properties and the potential application of a series of cost-effective electroactive nitrobenzene molecules in NAORFBs. Pairing the low-cost miscible liquid nitrobenzene (NB) with 2,5-di-tert-butyl-1-methoxy-4-(20-methoxyethoxy)-benzene (DBMMB) resulted in a flow battery that provides a high theoretical cell voltage of 2.2 V and a calculated energy density of 192 Wh L–1. In the charge–discharge testing, this battery delivers a stable cycling capacity retention of 99.5% per cycle over 100 cycles and a 70% energy efficiency at 40 mA cm–2 operation current density, verifying that liquid nitrobenzene is a promising low-cost electroactive anode molecule for NAORFBs.