Highly Stable Three Lithium Insertion in Thin V₂O₅ Shells on Vertically Aligned Carbon Nanofiber Arrays for Ultrahigh-Capacity Lithium Ion Battery Cathodes.

Brown, Emery; Acharya, Jagaran; Pandey, Gaind P.; Wu, Judy; Li, Jun

Here the authors demonstrate an approach to achieving stable 3 Li+ insertion into vanadium pentoxide (V2O5) by implementing a 3D core-shell structure consisting of coaxial V2O5 shells sputter-coated on vertically aligned carbon nanofiber cores. The hydrated amorphous microporous structure in the 'as-deposited' V2O5 shells and the particulated nanocrystalline V2O5 structure formed by thermal annealing are compared. The former provides remarkably high capacities of 360 and 547 mAh g−1 in the voltage range of 4.0-2.0 and 4.0-1.5 V, respectively, far exceeding values in current oxide-based lithium ion battery cathodes and even the corresponding 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. This is attributed to the additional reactions with the hydrated amorphous structure. After 100 cycles of 3 Li+/V2O5 insertion/extraction at 0.20 A g−1 (≈ C/3), ≈84% of the initial capacity is retained. After thermal annealing, the core-shell structure presents a capacity of 294 and 390 mAh g−1, matching well with the theoretical values for 2 and 3 Li+/V2O5 insertion. The annealed sample shows further improved stability, with a remarkable capacity retention of ≈100% and ≈88% for 100 cycles of 2 and 3 Li+/V2O5 insertion/extraction.

NANOSTRUCTURED materials synthesis; CARBON nanofibers; VANADIUM oxide; ANNEALING of crystals; INSERTION reactions (Chemistry); LITHIUM-ion batteries; MICROSTRUCTURE

Advanced Materials Interfaces, 2016, Vol 3, Issue 23, pn/a

2196-7350

Academic Journal

10.1002/admi.201600824