Facilitating high-capacity V2O5 cathodes with stable two and three Li+ insertion using a hybrid membrane structure consisting of amorphous V2O5 shells coaxially deposited on electrospun carbon nanofibers

Abstract

This study reports an approach to achieving stable 2 and 3 Li+ insertion, respectively, into vanadium pentoxide (V2O5) as lithium-ion battery (LIB) cathode materials using a core-shell structure based on a self-standing carbon nanofiber (CNF) membrane fabricated by an electrospinning process. Uniform coaxial V2O5 shells are coated onto continuous CNF cores via a pulsed electrodeposition. The materials analyses confirm that the V2O5 shell after 4 h of thermal annealing at 300 °C forms a partially hydrated amorphous structure. SEM and TEM images indicate that the uniform 30–50 nm thick V2O5 shell forms an intimate interface with the CNF core. Lithium insertion capacities up to 291 and 429 mAh g−1 are achieved in the voltage ranges of 4.0–2.0 V and 4.0–1.5 V, respectively, which are in good agreement with the theoretical values of 294 mAh g−1 for 2 Li+/V2O5 insertion and 441 mAh g−1 for 3 Li+/V2O5 insertion into crystalline V2O5 materials. Moreover, after 100 cycles, remarkable retention rates of 97% and 70% are obtained for 2 Li+/V2O5 and 3 Li+/V2O5 insertion, respectively. These results reveal that it is potentially feasible to fabricate the core-shell structure with electrospinning and electrodeposition processes to break the intrinsic limits of V2O5 and enabling this high-capacity cathode materials for future LIBs.