Catalysis Of Heteroatoms For Vanadium Ion Redox Reaction In Vanadium Redox Flow Battery

Vanadium flow battery system(VRFB)has been one of the most potential energy storage systems,with advantages of fast response,flexible design,and environmentally friendly.In VRFB,as one of key materials,electrodes provide reaction place for active species.Carbon-based materials(graphite felt,etc),with low cost,high conductivity and stability,have been widely used in VRFB.But,the poor electrochemical activity limits commerical applications of these materials.Heteroatoms doped carbon-based catalysts are studied to improve electrochemical activity of electrode for VO2+/VO2+ redox.P doped CNTs were prepared with phytic acid as P source.P atoms are incorporated into carbon layers of CNTs,without obvious effect on the morphologies of CNTs.The electrocatalytic properties of CNTs are significantly enhanced by P doping,and the sample treated at 800 ? exhibited the best electrocatalytic activity.The cell using CNTsP8 exhibited higher discharge capacity and energy efficiency.Carbon microspheres(CMS-C)are obtained by hydrothermal and high temperature carbonization,with glucose as raw materials.The CMS-N and CMS-NP are prepared by high temperature treatment with NH4 Cl and(NH4)2HPO4 as N and P sources,respectively.N and P atoms were incorporated into carbon microspheres frameworks,resulting in more structure defects and redistribution of charges on carbon microspheres surface.The electrochemical test results show that the electrochemical activity of carbon microspheres is enhanced in order of: CMS-NP > CMS-N > CMS-C.CMS-NP catalyst reduce battery polarization and improve battery energy density.The soaked fungus suffer hydrothermal treatment and calcination with KOH.The porous carbon with oxygen-containing groups(FDC-K)is obtained.Oxygen-containing groups improve the hydrophilicity of materials which promoted the mass transfer process on electrode surface.FDC-K had large surface and high porosity,which provided large active place for VO2+/VO2+ redox.The FDC-K is a low-cost,accessible and promising catalyst for VO2+/VO2+ redox.