Electrospun Na3V2(PO4)3/C nanofibers as stable cathode materials for sodium-ion batteries†
Sodium-ion batteries are considered as prime alternatives to lithium-ion batteries for large-scale renewable energy storage units due to their low cost and the abundance of sodium bearing precursors in the earth's mineral deposits. In the current work, a 3D NASICON framework Na3V2(PO4)3/carbon cathode electrode with 20–30 nm Na3V2(PO4)3 nanoparticles uniformly encapsulated interconnecting one-dimensional carbon nanofibers was fabricated using a simple and scalable electrospinning method. The Na3V2(PO4)3/C cathode showed an initial charge capacity of 103 mA h g−1 and a discharge capacity of 101 mA h g−1 (calculated on the total mass of Na3V2(PO4)3 and carbon) at 0.1C rate, and retained stable discharge capacities of 77, 58, 39 and 20 mA h g−1 at high current densities of 2C, 5C, 10C and 20C, respectively. Moreover, because of the efficient 1D sodium-ion transport pathway and the highly conductive network of Na3V2(PO4)3/C, the electrode exhibited high overall capacities even when cycled at high currents, extending its usability to high power applications.