Redox Targeting-Based Aqueous Redox Flow Lithium Battery

Abstract

Redox flow batteries (RFBs) have been extensively investigated because of their great operation flexibility and scalability for large-scale energy storage, yet they suffer from low energy density and relatively high cost when price per kWh is considered. Here, we report an aqueous redox flow lithium battery (RFLB) system based on the concept of Nernstian potential-driven redox targeting reactions of battery materials to address the above issues. With [Fe(CN)6]4–/[Fe(CN)6]3– and S2–/S22– as the redox mediators in the catholyte and anolyte, the cell reveals an anodic and cathodic volumetric capacity up to 305 and 207 Ah L–1 when LiFePO4 and LiTi2(PO4)3 are respectively loaded into the cathodic and anodic tank as energy storage materials. These are 4–6 times as high as that of the vanadium redox flow battery (VRB). In addition, with water-based electrolytes, the system presents notably enhanced Li+ conductivity in the membrane and consequently much improved power performance as compared to its nonaqueous counterpart. We anticipate that this work would be a paradigm and pave the way for the deployment of redox targeting-based flow battery technology for large-scale applications.