PVP-modulated synthesis of NaV6O15 nanorods as cathode materials for high-capacity sodium-ion batteries

Abstract

Highly uniform NaV6O15 nanorods were obtained via a facile and low-cost PVP-modulated hydrothermal process. It is largely accepted that such a unique feature is favorable for rapid diffusion for sodium ions according to the intrinsic crystal structure. As the cathode, the as-prepared NaV6O15 nanorods are capable of delivering a high initial capacity of approximately 157 mA h g−1 at 20 mA g−1 for potentials ranging from 1.5 to 3.8 V and yielding 121 mA h g−1 at a high current density of 200 mA g−1. EIS analysis results demonstrated that the diffusion coefficients DNa as high as 2.71 × 10−12 cm2 s−1 at room temperature. In addition, it could be clearly observed that the NaV6O15 exhibited metallic behavior from the electron density of states, providing excellent electron conductivity. All these results suggest that NaV6O15 nanorods can be a very promising cathode for sodium batteries.