3D interconnected porous carbon coated Na3V2(PO4)3/C composite cathode materials for sodium-ion batteries

Abstract 3D interconnected porous carbon coated Na3V2(PO4)3/C (NVP/C) composites were calcined after production using an improved sol-gel combustion method. A large surface area was produced from the porous structure, providing a charge transfer across the electrode/electrolyte interface, thereby shortening ion diffusion lengths. A 3D conductive network beneficial to electronic transport was formed by covering the thin walls of the 3D interconnected pores with a uniform and amorphous carbon layer. The electrochemical performance of the NVP/C composite was notably impacted by the thickness of the carbon layer, determined by the residual carbon content. When the precursor was added with 10 wt% glucose, the final NVP/C-G10% composite, having an optimum carbon layer thickness, achieved an exceptional electrochemical property, making it suitable for sodium-ion batteries (SIBs). At the rate of 0.2C, the NVP/C-G10% composite possessed a high capacity of 118.0 mAh/g. With a rate of 10 C, the NVP/C-G10% electrode exhibited an initial reversible capacity of 64.4 mAh/g; after 1000 cycles this electrode has a retention capacity of 81.5%. Cyclic voltammetry and electrochemical impedance spectroscopy results indicated that, under lower polarization, NVP/C-G10% composite had an increased sodium ion diffusion coefficient and reduced transfer resistance charge, resulting in a high rate performance and cyclic stability.