Designed One-Pot Strategy for Dual-Carbon-Protected Na3 V2 (PO4 )3 Hybrid Structure as High-Rate and Ultrastable Cathode for Sodium-Ion Batteries.

Sodium-ion batteries have attracted tremendous attention due to their much lower cost and similar working principle compared with lithium-ion batteries, which have been invited great expectation as energy storage devices in grid-level applications. The sodium superionic conductor Na3 V2 (PO4 )3 has been considered as a promising cathode candidate; however, its intrinsic low electronic conductivity results in poor rate performance and unsatisfactory cycling performance, which severely impedes its potential for practical applications. Herein, we developed a facile one-pot strategy to construct dual carbon-protected hybrid structure composed of carbon coated Na3 V2 (PO4 )3 nanoparticles embedded with carbon matrix with excellent rate performance, superior cycling stability and ultralong lifespan. Specifically, it can deliver an outstanding rate performance with a 51.5 % capacity retention from 0.5 to 100 C and extraordinary cycling stability of 80.86 % capacity retention after 6000 cycles at the high rate of 20 C. The possible reasons for the enhanced performance could be understood as the synergistic effects of the strengthened robust structure, facilitated charge transfer kinetics, and the mesoporous nature of the Na3 V2 (PO4 )3 hybrid structure. This work provides a cost-effective strategy to effectively optimize the electrochemical performance of a Na3 V2 (PO4 )3 cathode, which could contribute to push forward the advance of its practical applications.