Research progress on heteroatom-doped electrodes used in all vanadium redox flow batteries
Flow batteries are indispensable technologies for large-scale energy storage,owing to their inherent safety and exceptionally long lifespan.In all-vanadium redox flow batteries(VRFBs),the electrode material is a crucial component,as its interface characteristics with the electrolyte substantially influence battery performance.Surface modification methods applied to the electrode facilitate enhancements in electrochemical activity,particularly under high current density conditions.Currently,electrode surface heteroatom doping technology is a focal point of research.This study summarizes the mechanisms and research progress of heteroatom doping in graphite felt(GF),specifically emphasizing two doping strategies:in-situ doping within the carbon framework and utilizing heteroatom catalysts on the electrode surface.This study also comprehensively summarizes doping types and performance differences associated with these two strategies.It explains the principles of in-situ doping in electrode materials based on the electronegativity and atomic size of heteroatoms,along with discussing how heteroatoms affect the electronic structure of carbon fibers.Additionally,it introduces the impact patterns of three carbon-based catalysts—heteroatom-doped porous carbon materials,carbon nanotubes,and graphene—on the electrochemical performance of electrode materials.The comprehensive analysis indicates that heteroatom doping on the electrode surface can increase active sites for electrode reactions,promote the migration of active ions,improve hydrophilicity,and enlarge the effective contact area between the electrode and electrolyte.Furthermore,the study suggests adopting methods such as regulating the charge distribution on the electrode surface,varying functional group types,and constructing defect sites to effectively enhance electrode materials'stability and electrochemical performance,ultimately leading to increased electrochemical activity at high current densities and higher conductivity.
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