Uniform Carbon Coated Na3V2(PO4)2O2xF3 − 2x Nanoparticles for Sodium Ion Batteries as Cathode

Abstract

A uniform carbon-coated Na3V2(PO4)2O2xF3 − 2x (NVPOF/C) nanoparticle synthesized by a novel pyro synthesis method is utilized for sodium-ion batteries (SIBs) as a cathode. Remarkably, the electrochemical properties are performed at high rates show significantly improved discharge capacity (Fig. 1). At 0.1 C, the NVPOF/C cathode shows a discharge capacity of 130 mAh g− 1, corresponding to 100% of the theoretical capacity. Even at 50 C, a discharge capacity of ~85 mAh g− 1 could be attained. The in situ X-ray diffraction and ex-situ synchrotron X-ray absorption near edge structure spectroscopy results exposed that the reversible sodium ion insertion/ extraction into/from NVPOF/C host structure occurs with a small volume change (3.4%), indicating the structural stability of the cathode. Our study validates that the Na3V2(PO4)2O2xF3 − 2x/C electrode is a promising candidate for developing high power/ energy density cathodes for SIBs.Figure 1. (a) Galvanostatic charge/discharge potential profiles of Na3V2(PO4)2O2xF3-2x in the potential range of 2.0 ~ 4.3V at 0.1C. (b) Cycle performance at 1C. (c) The discharge profiles of different C. (d) Comparison of the rate capabilities at various curve Figure 1