Nernstian-Potential-Driven Redox-Targeting Reactions of Battery Materials

Redox flow batteries have great system scalability and operational flexibility but relatively low energy density because of the limited solubility of redox molecules in the electrolytes. By storing energy in solid materials while producing power from redox fluids, the redox-targeting concept provides an effective way to significantly increase the energy density of flow batteries. Redox targeting generally involves multiple redox reactions between the molecules and materials, which inevitably brings about additional complexity in electrolyte composition and low voltage efficiency. The Nernstian-potential-driven redox-targeting reaction reported here considerably eliminates the voltage loss of a LiFePO4-based redox flow lithium battery. Driven by the Nernstian potential difference, the redox molecule, a ferrocene-grafted ionic liquid with standard potential identical to that of LiFePO4, reacts with the solid material both anodically and cathodically and exhibits near-unity material utilization, a voltage efficiency of 95%, and an energy density of 330 Wh/L (up to 942 Wh/L).