Non-aqueous redox flow battery (NARFBs) is an electrochemical energy storage device with great promise to achieve a high energy density owing to the broader electrochemical window than aqueous systems. However, their cycling performance and battery efficiency are generally limited due to the low solubility of active materials in organic solvents and high resistance of organic systems. To address these problems, we demonstrate a new non-aqueous all-organic flow battery based on organometallic iron with a high solubility in acetonitrile. The ferrocene molecule incorporated with tetraalkylammonium ionic is used as the anolyte active material, which has a higher solubility and redox potential than pure ferrocene. Both of the anolyte and catholyte active materials are iron-based species and there is no reaction between them, and the battery system is designed as a mixed electrolyte to avoid cross-contamination. A Daramic porous separator is used in this organic flow battery. The cell shows a stable performance within 200 charge-discharge circles at a current density of 10 mA cm<sup>−2</sup>, superior to most of other non-aqueous flow systems. Benefit from the high solubility, superior chemical stability and fast kinetics of the active materials, the battery achieves a high cycle performance with a stable Coulomb efficiency around 95.9%, voltage efficiency of around 71.4% and energy efficiency of around 68.5% over 200 cycles. These results indicate that the iron-based metal-organics non-aqueous redox flow battery is quite promising.

All-iron non-aqueous redox flow battery with a high performance and stability

2019 Spring National Meeting

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