Effect of Pre-Oxidation of Electrospun Polyvinylpyrrolidone-Derived CoxP/C Composite Nanofibers on their Electrochemical Performance as Anode in Lithium-Ion Batteries

Abstract

This research studies the effect of pre-oxidation on physical and electrochemical properties of electrospun polyvinylpyrrolidone (PVP)-derived carbon composites of cobalt phosphides by comparing carbonized non-pre-oxidized (NPO) and pre-oxidized (PO) samples used as anode materials for lithium-ion batteries. The X-Ray diffraction (XRD) patterns revealed the formation of CoP and Co₂P in both samples while presence of amorphous cobalt metaphosphate for NPO and cobalt phosphate for PO was determined by X-ray photoelectron spectroscopy (XPS). The electrochemical performance of nanofibers was evaluated by cyclic voltammetry and galvanostatic charge-discharge at different current densities. The results showed improved stability at high current densities (344.1 mAh g^-1 at 5000 mA g^-1), more significant charge capacity (599.6 mAh g^-1 at 500 mA g^-1) and higher initial Coulombic efficiency (CE%, 61.1%) for PO samples than NPO.