Realizing Efficient Sodium Storage Property with NASICON-type Na2VTi(PO4)3 Modified by Nitrogen and Sulfur Dual-doped Carbon Layer for Sodium Ion Batteries

Abstract As a promising cathode for sodium ion batteries, polyanion-type phosphate compounds are considered as a potential candidate of the next-generation sodium storage materials for the three-dimensional (3D) structure and open pathways. However, several intrinsic faults, such as low electrical conductivity seriously prevent their practical application in broader fields. Herein, the nitrogen and sulfur co-doped carbon layer coated Na2VTi(PO4)3 nanocomposites have been synthesized by a facile sol-gel method. The crystal structure, surface morphology and charge-discharge performance were investigated to confirm the successful preparation of target particles and the substitution of nitrogen and sulfur elements. Among these prepared materials, the optimal sample can display a satisfactory discharge capacity of 164.85 mAh g-1 and high capacity retention of 96.5% after thirty cycles. Meanwhile, the superior rate properties and rapid reaction kinetics are achieved as a result of high electrical conductivity and fast ion diffusion coefficient, resulting in an enhanced electrochemical performance. The route in this paper may provide guidance to a large-scale commercial production of energy storage devices.