Investigation On Electrochemical Performance Of The Modified Graphite Felt In Anthraquinone Derivatives Solution

Quinone-based flow batteries have received extensive attention as a new type of organic flow battery which use anthraquinone derivatives as electrolyte.It has a lot of advantages such as safety,environmental friendliness,low price.The electrode material is an important component to improve the performance of batteries,while graphite felt material as the electrode materials of quinone-based flow batteries has not been reported.This thesis mainly explores the surface modification of the graphite felt and the influence of modification on the electrocatalytic effects of five kinds of anthraquinone derivatives electrolyte.The graphite felt electrode has been modified through four approaches: heat treatment,acid treatment,mixed treatment,and nitrogen-doping treatment.Scanning electron microscope(SEM),X-ray diffraction(XRD),and X-ray photoelectron spectroscopy(XPS)were employed to study the surface microstructure,crystal structure and surface chemical state of the resultant modified graphite felt electrode.The electrocatalytic performance of electrode was evaluated by cyclic voltammograms(CV)and AC impedance spectroscopy.The result show that,surface modification of graphite felt by the four approaches reduces the impurities in carbon fibre,decreases the lattice parameters of graphite felts,and increases the content of oxygen-containing functional groups at the surface,which contributes to improved electrocatalytic performance of graphite felt for redox reaction of anthraquinone derivatives,as proved by electrochemical tests.Especially,the modification in air shows the highest degree of improvement.It is also found that the heat-treatment temperature and duration have some impact on the electrocatalytic performance.Further more,the changes in species,number and replacement position for the functional groups in anthraquinone derivatives have certain effect on the redox reaction process.The more the surface functioned groups,and the closer the replacement position to C=O,the more obvious the resistance to anthraquinone derivatives redox reaction.In summary,the graphite felt modified by heating at 550 for 3 hours in air in anthraquinone-2-sulfonate sodium electrolyte solution has the best performance in terms of electrocatalytic activity and reversibility.