Redox flow battery (RFB) is considered as the most promising grid-scale energy storage technology. Non-aqueous RFB systems show high performance and wide working temperature window. Herein, it has become one of the research hotspots to develop a new generation of high energy density non-aqueous RFB. Several non-aqueous organic RFBs with high open-circuit voltages are developed in this work. The alkoxybenzene derivatives are synthesized, and the alteration of poly ethylene oxide (PEO) chains is expected to improve their solubility and keep the electrochemical stability. The cyclic voltammetry results show high electrochemical stability of all the cathode and anode active materials. Besides, three different anode active materials (fluorenone, acylamide and heterocyclic compounds) are tested and compared in flow cells with the same cathode active material, which demonstrates that all the cells have a voltage of beyond 2.0 V and the battery employing alkoxybenzene derivatives and heterocyclic compounds have a higher cycling stability. In addition, a number of Daramic and Ceglard porous separators are tested to examine the effects of key separator parameters (i.e., thickness and pore size) on flow cell performance. The flow cell with Daramic-250 porous separator shows high capacity and stable efficiencies with an average of coulombic efficiency 91.5%, voltage efficiency 87.8%, and energy efficiency 80.4% throughout 100 charge-discharge cycles, and material utilization of ca. 60% for 100 cycles.

Electrochemical properties of all-organic non-aqueous redox flow battery with highly soluble active materials

2019 Spring National Meeting

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