Carbon decorated Na3V2(PO4)3 nanoparticles as a high-rate-capability cathode for fast chargeable sodium-ion batteries

Abstract

Reducing size of Na₃V₂(PO₄)₃ (NVP) into nanoscale is regarded as an effective way to improve its high-rate performance for sodium-ion storage. However, the current synthetic approaches for nanostructured NVP such as sol-gel, hydrothermal, and electrospinning still possess limitations in terms of long reaction time and complicated operation. Here, we combine high-boiling organic solvent-assisted colloidal synthesis (HOS-CS) and calcination to fabricate carbon-coated NVP nanoparticles (NPs) with the size of about 50 nm distributed in carbon nanotubes scaffolds as the cathode for SIBs. This HOS-CS strategy demonstrates unique merit of short synthetic period, solving the problem of previously-known approaches in the aspect of synthetic efficiency. Impressively, NVP@C@MWCNTs offers up to 108.6 mAh g^-1 at 0.5 C, and also achieves 83.67 and 67.6 mAh g^-1 of initial capacities nearly 80 % and 76.1 % of retention after 3000 cycles at ultrahigh rates of 30 C and 50 C, respectively. More surprisingly, the NVP@C@MWCNTs cathode is matched with the hard carbon (HC) anode to construct NVP@C@MWCNTs||HC full cell, delivering as high as 71 mAh g^-1 of initial capacity with 72.8 % of retention after 500 cycles even at 10 C. This work provides an efficient strategy for synthesizing high-rate-capability NVP-based cathode towards fast chargeable SIBs.