Carbon Material and Electrolyte Composition Effects on the Performance of Prussian White Solid Boosters in Flow Batteries.

Prussian White-based boosters were prepared using four commercially available carbon materials as conductive additives and cycled at the storage tanks of flow batteries with ferri/ferrocyanide-based electrolytes. All systems underwent a 21-22 day charge-discharge cell test to assess their long-term cycling stability; boosters containing the carbon material YP-50F completed nearly twice as many cycles as the other studied carbons (e.g., 500 vs 194, for YP-50F and C65, respectively), exhibiting their faster charge-discharge behavior. Changing the carbon material had a slight effect on the capacity utilization of the solid boosters (variations ∼10% under similar conditions), and this trend persisted across all remaining experiments. A significant improvement in capacity was observed when increasing the ferri/ferrocyanide concentration from 0.1 mol L-1 to 0.8 mol L-1 in the electrolyte solution, with the maximum capacity utilization increasing from 22.1% to 94.8% for a booster made with YP-50F carbon material. The results suggest that the increased booster utilization capacity observed at higher electrolyte concentrations is related to an enhanced mass transfer through the particles and a better matching between the redox potential of the boosters and the electrolyte.