Controllable synthesis and in situ TEM study of lithiation mechanism of high performance NaV3O8 cathodes†
NaV3O8 nanobelts, nanorods and microrods have been successfully synthesized using a facile, one-step solid-state sintering method. The morphology, crystallinity and purity of NaV3O8 can be easily controlled by the calcination temperature. As a cathode material for Li-ion batteries, NaV3O8 nanorods synthesized at 450 °C show a relatively higher specific discharge capacity of 226 mA h g−1 at 30 mA g−1 and a good cycling performance without considerable capacity loss over 100 cycles at 100 and 300 mA g−1. In situ TEM characterization confirmed that the intercalation/deintercalation of Li+ ions in NaV3O8 is a single-phase reaction process with small lattice change, which can result in obvious cracks and fractures. The SEM characterizations of the electrodes after cycling reveal that the structure destruction is the main reason for the capacity fading of NaV3O8.