Highly stable and nanoporous Na3V2(PO4)3@C cathode material for sodium-ion batteries using thermal management

Abstract

Sodium vanadium phosphate (Na3V2(PO4)3-NVP) a NASICON-type material with exceptionally high ionic conductivity is acknowledged as a potential cathode for high-performance Na-ion batteries. Herein, we report a facile sol-gel process for the preparation of NVP@C. The NVP@C produced has rhombohedral NASICON crystal structure and exhibit 3D interlink microstructure with porous morphology and carbon network. The NVP@C prepared at 900 °C display an initial discharge capacity of 99 mAhg−1 at a current density of 1C and ultralong lifespan of 1400 cycles at 10C (73 mAhg−1) with 93 % capacity retention. This superior electrochemical performance is attributed to the synergistic effect of high crystallinity, porous structure & conducting carbon network. This provides a high contact area between electrode/electrolyte, better electronic conductivity, and high mechanical strength. Additionally, this will also responsible for easy diffusion of electrolyte and speedy transport of ions which ultimately helps to accelerate the electrochemical performance. It is noteworthy that the prepared NVP@C shows highly stable electrochemical performance at higher current density (10C) with 100 % columbic efficiency. More significantly, the full cell comprising NVP@C electrodes showed capacity retention of 80 % after 500 cycles at 2C rate. These prima fascia result shows the potential of the process which provides a new understanding to design other cathode material.