Micro/Nano Na3V2(PO4)3/N-Doped Carbon Composites with a Hierarchical Porous Structure for High-Rate Pouch-Type Sodium-Ion Full-Cell Performance.

Polyanion-type Na3V2(PO4)3 (NVP) is an overwhelmingly attractive cathode material for sodium-ion batteries (SIBs) because of its high structural stability and fast Na+ mobility. However, its practical application is strongly plagued by either nanoscale particle size or poor rate performance. Herein, a micro/nanocomposite NVP cathode with a hierarchical porous structure is proposed to solve the problem. The microscale NVP material assembled by interconnected nanoflakes with N-doped carbon coating that is capable of simultaneously providing fast carrier transmission dynamics and outstanding structural integrity exhibits precedent sodium-storage behavior. It delivers a superior rate capability (79.1 mAh g-1 at 200C) and excellent long-life cycling (capacity retention of 73.4% after 10 000 cycles at 100C). Remarkably, a pouch-type sodium-ion full cell consisting of the as-obtained NVP cathode and a hard carbon anode demonstrates the gravimetric energy density as high as 212 Wh kg-1 and an exceptional rate performance (71.8 mAh g-1 at 10C). Such structural design of fabricating micro/nanocomposite electrode materials is expected to accelerate the practical applications of SIBs for large-scale energy storage.