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

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 co-axial 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 degrees 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. (C) 2018 Elsevier Ltd. All rights reserved.