Carbon Nanolayer-Coated Na3V2(PO4)3 Nanocrystals Embedded in Conductive Carbon Matrix as High-Performance Cathode for Sodium-Ion Batteries

Na3V2(PO4)(3) is a promising cathode material for sodium-ion batteries. However, the design of appropriate carbon coatings is necessary for improving the Na-storage performance of this material to overcome the intrinsically low electron conductivity and therefore sluggish reaction kinetics. Herein, carbon nanolayer-coated Na3V2(PO4)(3) nanocrystals embedded in a conductive carbon matrix (NVP/C) are fabricated by using a facile in-situ synthesis method with controlled utilization of graphene-oxide nanosheets. Structural and electrochemical properties of the as-synthesized NVP/C material are analyzed by combining X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscope, transition electron microscope, and electrochemical measurements. The optimized NVP/C material exhibits a unique nanostructure consisting of Na3V2(PO4)(3) nanocrystals with an average size of similar to 60 nm and carbon nanolayers with uniform thickness of similar to 5 nm. As electrode, the material delivers a high reversible capacity of 114.8 mAhg(-1) at 0.2 C, superior high-rate capability with a discharge capacity of 101.8 mAhg(-1) at 10 C, and excellent cycling performance with capacity retention of 91% after 1000 cycles. The finding indicates that constructing carbon-coating nanolayers and a conductive carbon matrix is an important strategy to achieve high-quality NVP/C material for advanced sodium-ion batteries.