Performance enhancement of alkaline organic redox flow battery using catalyst including titanium oxide and Ketjenblack

Carbon felt (CF) doped by catalyst including titanium oxide and ketjen black (TiO2/KB-CF) is used as negative electrode to enhance the redox reactivity of napthoquinone (NQSO) and thus the performance of aqueous organic redox flow batteries (AORFBs). The redox reactivity of NQSO is better with TiO2/KB-CF than with pristine CF (anodic current density of 13.3 and 19.8 mA center dot cm(-2), and cathodic current density of -15.7 and -21.9 mA center dot cm(-2) with pristine CF and TiO2/KB-CF), while the reaction reversibility of NQSO is also enhanced in TiO2/KB-CF (ratio of peak current density is 0.84 and 0.9 with pristine CF and TiO2/KB-CF). These results are due to the hydrophilic and conductive properties of the TiO2/KB catalyst. TiO2 can hold many hydroxyl groups that are hydrophilic and electro-active group, while KB is a conductive material that induces a fast electron transfer. With these benefits, the charge transfer resistance of the electrode is reduced from 1.8 omega with pristine CF to 1.5 omega with TiO2/KB-CF. In AORFB tests using NQSO and potassium ferrocyanide under alkaline supporting electrolyte, energy efficiency increased from 58% (pristine CF) to 61% (TiO2/KB-CF) with a low capacity loss rate of 0.006 Ah center dot 17(-1) per cycle and the cross-over rate of active materials during cycling of AORFB was very low.

Automated summary

Carbon felt doped with titanium oxide and ketjen black (TiO2/KB-CF) is used as a negative electrode to improve the redox reactivity and performance of aqueous organic redox flow batteries. The hydrophilic and conductive properties of the TiO2/KB catalyst contribute to the enhanced reaction and reversibility of napthoquinone, resulting in reduced charge transfer resistance of the electrode. The AORFB tests using TiO2/KB-CF show increased energy efficiency and low capacity loss rate.