High–energy density nonaqueous all redox flow lithium battery enabled with a polymeric membrane

TLDR

Redox flow batteries are promising for large‑scale energy storage but are limited by low energy density due to low solubility of active materials. This study proposes a redox flow lithium battery that uses redox‑targeting reactions to dramatically increase energy density. The RFLB employs LiFePO₄ and TiO₂ as cathodic and anodic lithium storage materials, achieving a tank energy density of ~500 Wh L⁻¹ at 50 % porosity. The prototype delivers tenfold higher energy density than vanadium RFBs and retains good electrochemical performance over extended cycling, demonstrating feasibility for large‑scale storage.

Abstract

Redox flow batteries (RFBs) are considered one of the most promising large-scale energy storage technologies. However, conventional RFBs suffer from low energy density due to the low solubility of the active materials in electrolyte. On the basis of the redox targeting reactions of battery materials, the redox flow lithium battery (RFLB) demonstrated in this report presents a disruptive approach to drastically enhancing the energy density of flow batteries. With LiFePO4 and TiO2 as the cathodic and anodic Li storage materials, respectively, the tank energy density of RFLB could reach ~500 watt-hours per liter (50% porosity), which is 10 times higher than that of a vanadium redox flow battery. The cell exhibits good electrochemical performance under a prolonged cycling test. Our prototype RFLB full cell paves the way toward the development of a new generation of flow batteries for large-scale energy storage.