One promising candidate for high-energy storage systems is the nonaqueous redox flow battery (NARFB). However, their application is limited by low solubility of redox-active materials and poor performance at high current density. Reported here is a new strategy, a biredox eutectic, as the sole electrolyte for NARFB to achieve a significantly higher concentration of redox-active materials and enhance the cell performance. Without other auxiliary solvents, the biredox eutectic electrolyte is formed directly by the molecular interactions between two different redox-active molecules. Such a unique electrolyte possesses high concentration with low viscosity (3.5 m, for N-butylphthalimide and 1,1-dimethylferrocene system) and a relatively high working voltage of 1.8 V, enabling high capacity and energy density of NARFB. The resulting high-performance NARFB demonstrates that the biredox eutectic based strategy is potentially promising for low-cost and high-energy storage systems.
Keywords: batteries; electrolytes; energy storage; hydrogen bonding; redox chemistry.
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