Rational design of few-layer FePS3 nanosheets@N-doped carbon composites as anodes for sodium-ion batteries

The development of anode materials with high-rate capability and long cyclability has become a research hotspot for sodium-ion batteries (SIBs). In this work, we propose a simple and convenient method for the synthesis of few-layered FePS3 nanosheets modified by N-doped carbon (FePS3@NC) through a controllable coating of polydopamine on the surface of exfoliated FePS3 nanosheets followed by subsequent carbonization. The optimized FePS3@NC anode exhibits a superior capacity performance for 800 cycles with a high specific capacity of 281 mAh g−1 at 1.0 A g−1 due to high ionic conductivity of metal phosphorus trichalcogenides (MPS3) and the unique two-dimensional (2D) few-layered structure of ultrathin nanosheets. Besides, the N-doped carbon layer (NC) decreases Na+ diffusion resistance and buffers the volumetric change during cycles, which are validated by the ex-situ X-ray diffraction and density functional theory (DFT) calculations. Furthermore, the full cell coupled by FePS3@NC anode and Na3V2(PO4)3/carbon (NVP/C) cathode also displays high cycling stability. This work gives insight into the development of superior properties anodes for SIBs based on two-dimensional (2D) van der Waals crystals.