【摘 要】
：
Herein,the electrochemical performance and the mechanism of potassium insertion/deinsertion in orthorhombic V2O5 nanoparticles are studied.The V2O5 electrode displays an initial potassiation/de-potassiation capacity of 200 mAh g-1/217 mAh g-1 in the volta
【机 构】
：
Institute for Applied Materials(IAM),Karlsruhe Institute of Technology(KIT),Hermann-von-Helmholtz-Pl
论文部分内容阅读
Herein,the electrochemical performance and the mechanism of potassium insertion/deinsertion in orthorhombic V2O5 nanoparticles are studied.The V2O5 electrode displays an initial potassiation/de-potassiation capacity of 200 mAh g-1/217 mAh g-1 in the voltage range 1.5-4.0 V vs.K+/K at C/12 rate,suggesting fast kinetics for potassium insertion/deinsertion.However,the capacity quickly fades during cycling,reaching 54 mAh g-1 at the 31st cycle.Afterwards,the capacity slowly increases up to 80 mAh g-1 at the 200th cycle.The storage mechanism upon K ions insertion into V2O5 is elucidated.In operando synchrotron diffraction reveals that V2O5 first undergoes a solid solution to form K0.6V2O5 phase and then,upon further K ions insertion,it reveals coexistence of a solid solution and a two-phase reaction.During K ions deinsertion,the coexistence of solid solution and the two-phase reaction is identified together with an irreversible process.In operando XAS confirms the reduction/oxidation of vanadium during the K insertion/extraction with some irreversible contributions.This is consistent with the results obtained from synchrotron diffraction,ex situ Raman,X-ray photoelectron spectroscopy(XPS),and transmission electron microscopy(TEM).Moreover,ex situ XPS confirms the“cathode electrolyte interphase”(CEI)formation on the electrode and the decomposition of CEI film during cycling.
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