Non-aqueous redox flow batteries with nickel and iron tris(2,2 ′-bipyridine) complex electrolyte

摘要

An organic redox flow battery adopting tris(2,2 ′- bipyridine)nickel(II)tetrafluoroborate (Ni(Bpy) _3(BF _4) _2) and tris(2,2 ′-bipyridine)iron(II) tetrafluoroborate (Fe(BPy) _3(BF _4) _2)) in propylenecarbonate electrolyte is investigated. With cyclic voltammetry, the redox current of one-electron related Fe(II)Fe(III) and two-electron related Ni(II)Ni(0) appears at 0.65 V and -1.66 V (vs. AgAg), respectively and their cycleabilities are highly stable during 100 cycles. Their charge-discharge characteristics on the carbon-felt electrodes are evaluated with 0.4 M Fe(Bpy) _3(BF _4) _2 and 0.2 M Ni(Bpy) _3(BF _4) _2 which are adopted as catholyte and anolyte. Comparing with the aqueous system, the higher cell voltage of 2.2 V was achieved and initial coulombic and energy efficiencies were reached with 90.4 and 81.8.