The 1.5 mol L1 V3þ negative electrolyte (0.75 mol L1 V2(SO4)3 in 3.0 mol L1 H2SO4) was obtained by electrolyzing the VO2þ positive electrolyte. 50 mL of these two electrolytes were stored in two separate glass reservoirs with jeckets and circulated into each half cell using peristaltic pumps at the rate of 50 mL min1