Nanostructured V2O5.nH2O/cup-stacked carbon nanotube composite with remarkable Li+ specific capacity

Nanostructures for lithium intercalation can be obtained by combining carbon nanotubes with nanoparticles, to achieve a composite that can be applied as electrochemical energy storage device. Depending on the chemical composition and architecture of the nanostructure, it can be used to develop batteries, supercapacitors, or hybrid battery-supercapacitor devices. Here, we study how the V2O5.nH2O concentration affects lithium intercalation into the V2O5.nH2O/cup-stacked carbon nanotube (CSCNTs) nanostructure. First, CSCNTs were directly grown on the surface of a nonwoven carbon fiber felt (CF). Then, ε/δ-V2O5.nH2O was electrodeposited on the CF/CSCNT composite. Between 4.2 and 1.5 V, 34 wt% V2O5.nH2O load provided lithium specific capacity of 633 mAhg−1 at 0.5 Ag−1 for 300 discharge/charge cycles with lower fading capacity. Higher or lower V2O5.nH2O load diminished this performance. Depending on the V2O5.nH2O load and scan rate, this new nanostructure can also operate as a pseudo-capacitor, to deliver 610 F g−1 at a scan rate of 10 mV s−1 between 4.0 and 1.5 V. We discuss this dependence in terms of V2O5.nH2O morphology and the presence of a junction between CSCNTs and V2O5.nH2O.