摘要
Methyl viologen （MV） as a bench-mark anolyte material has been frequently applied in aqueous organic redox flow batteries （AORFBs） towards large-scale renewable energy storage. However, only the first re- duction of MV was utilized in aqueous electrolytes because of the insoluble MV0generated from the second reduction of MV. Herein, we report that methyl viologen with bis（trifluoromethane）sulfonamide counter anion, MVTFSI, can achieve two reversible reductions in a nonaqueous supporting elec- trolyte. Paired with （Ferrocenylmethyl）trimethylammonium bis（trifluoromethanesulfonyl）imide, FcNFFSI, as catholyte, the MVTFS/FcNTFSI nonaqueous organic redox flow battery （NOARFB） can take advantage of either one electron or two electron storage of the methyl viologen moiety and provide theoretical energy density of 24.9Wh/L and a cell voltage of up to 1.5V. Using a highly conductive LiTFSI/CH_3CN supporting electrolyte and a porous Daramic separator, the NOARFB displayed excellent cycling performance, includ- ing up to a 68.3g energy efficiency at 40 mA/cm2, and more than 88g total capacity retention after 100 cycles.
Methyl viologen （MV） as a bench-mark anolyte material has been frequently applied in aqueous organic redox flow batteries （AORFBs） towards large-scale renewable energy storage. However, only the first re- duction of MV was utilized in aqueous electrolytes because of the insoluble MV0generated from the second reduction of MV. Herein, we report that methyl viologen with bis（trifluoromethane）sulfonamide counter anion, MVTFSI, can achieve two reversible reductions in a nonaqueous supporting elec- trolyte. Paired with （Ferrocenylmethyl）trimethylammonium bis（trifluoromethanesulfonyl）imide, FcNFFSI, as catholyte, the MVTFS/FcNTFSI nonaqueous organic redox flow battery （NOARFB） can take advantage of either one electron or two electron storage of the methyl viologen moiety and provide theoretical energy density of 24.9Wh/L and a cell voltage of up to 1.5V. Using a highly conductive LiTFSI/CH_3CN supporting electrolyte and a porous Daramic separator, the NOARFB displayed excellent cycling performance, includ- ing up to a 68.3g energy efficiency at 40 mA/cm2, and more than 88g total capacity retention after 100 cycles.
基金
Utah State University for providing faculty startup funds
the Utah Science Technology and Research initiative (USTAR) UTAG award for supporting this study
China CSC Study Abroad program
Utah Energy Triangle Student Award for supporting his graduate program
