The impact of modified electrode on the performance of an DHAQ/ K4Fe(CN)6 redox flow battery

Abstract

In this paper, the adsorption behavior and electronic transition ability of the five isomers of dihydroxyanthraquinone on different carbon materials are investigated from the perspective of molecular dynamics. The modification of carbon fiber is carried out by means of metal salt solution impregnation-high temperature etching. The surface morphology, crystal structure, element content and surface chemical state of the modified electrode are characterized by SEM, XRD, and XPS. The electrochemical performance of the modified electrode is evaluated by cyclic voltammetry, electrochemical impedance spectra and single cell. The results show that 1,8-DHAQ has the middle adsorption energy on carbon, and its electronic transition ability is the best. Rayon-based carbon fibers etched with nickel chloride have dense pores, while PAN-based carbon fibers have larger pores on the surface. This shows that nickel chloride has different catalytic effects on different carbon materials. After etching, the electrocatalytic activity of graphite felt increased nearly 4 times. The reason why the Rayon-based graphite felt can obtain higher electrocatalytic activity may be related to the increase in the relative proportion of doped nitrogen and carbonyl groups. Compared with pristine graphite felt, the etched porous electrodes have improved charge and discharge capacity and coulomb efficiency.