Performance Study of Nickel Oxide Graphite Felts as Electrode Materials for Ferrochromium Flow Batteries

Herein, the performance of nickel-oxide-modified graphite felts as electrode materials for Fe/Cr liquid flow batteries is investigated by combining density functional theory and experiments. The results show that the adsorption of NiO on Fe/Cr ions is more stable than that on graphite felt, and more electrochemically active sites are provided. The charge transfer after adsorption is larger, which is more conducive to the redox reaction during the charging and discharging processes. Finally, the experimental results further prove that the first discharge capacity of the nickel oxide-modified graphite felt reaches 22.0 Ah L <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics> <mml:mrow><mml:msup><mml:mo></mml:mo> <mml:mn>-1</mml:mn></mml:msup> </mml:mrow> <mml:annotation>$^{-1}$</mml:annotation></mml:semantics> </mml:math> , which is much higher than that of the unmodified graphite felt (12.4 Ah L <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:semantics> <mml:mrow><mml:msup><mml:mrow></mml:mrow> <mml:mrow><mml:mi></mml:mi> <mml:mo>-</mml:mo> <mml:mn>1</mml:mn></mml:mrow> </mml:msup> </mml:mrow> <mml:annotation>$^{-1}$</mml:annotation></mml:semantics> </mml:math> ). In addition, its energy efficiency could reach up to 59.5%, which is 27.3% higher than that of the original electrode.