Ultrathin Na1.08V3O8 nanosheets—a novel cathode material with superior rate capability and cycling stability for Li-ion batteries

Abstract

A novel two-step approach was developed to fabricate well-dispersed Na 1.08 V 3 O 8 nanosheets, which consist of ultra-thin monolayer sheets with a thickness of ca. 10 nm. The formation mechanism of nanosheets involves the fusion and conversion of nanorods. When used as a cathode material for Li-ion batteries, the nanosheets show superior rate capability, with discharge capacities of ca. 200.0, 131.3, 109.9, 94.2 and 72.5 mA h g À1 at 0.4, 10, 20, 30 and 50 C, respectively. Excellent cycling stability without considerable capacity loss over 200 cycles is observed at 600 and 1000 mA g À1 . It is believed that the unique nanosheet morphology as well as its intrinsic structural features greatly facilitate the kinetics of Li-ion diffusion and excellent structure stability, thus resulting in superior electrochemical performance.

Multi-layered Al2O3/LixV2O5/LiV3O8 nanoflakes with superior cycling stability as cathode material for Li-ion battery

“…2b is the high resolution of V2p after fitting. Peak at 517.4 eV and 524.6 eV are attributed to the spin-orbit splitting of V 5+ 2p3/2 and V 5+ 2p1/2, which are well consistent with the valence in references [37,38]. (Fig.…”

Catalytic behavior of NaV6O15 bronze for partial oxidation of hydrogen sulfide

“…However, a week intensity contribution centered at 515.5 eV indicates the presence of a small amount of V 4+ in Na-containing catalyst, but the V 4+ /V 5+ surface ratio increases when increasing the Na-content confirming that the materials consists of mixed valance state vanadium atoms ( Table 2). This is in agreement with previous results with Na-containing vanadium oxide bronzes [24].…”

“…The deconvolution of the V 2p3/2 region confirms that the incorporation of 10 sodium favors a higher reduction of V-atoms [24,29]. V 5+ is mainly present in Na-free sample as deduced from the fact that the peak is centered at 517.2 eV.…”

“…In fact, AxV6O15 are in a mixed-valence state of V 4+ and V 5+ , so that in the case of NaV6O15 the formal valence is V 4.83+ [35], whereas α-NaV2O5 and NaV3O8 has an average state of vanadium of 4.5 [36] and 4.93, respectively [24].…”

“…In the same way, with respect to the V-O-V stretching vibration in pure V2O5, it was broad and shifts toward the low frequency upon the Na + addition. On the other hand, the bands at 955 and 970 cm -1 in the sample with higher Na/V ratio can be related to the presence of NaV3O8 [24]. Table 1 summarizes the H2-uptake achieved during the TPR-H2 experiments.…”