Polyvinylpyrrolidone-derived nitrogen-doped carbon-coated MoS2 composites for enhanced sodium storage performance

Abstract

Two-dimensional transition metal dichalcogenides, which display considerable theoretical capacity and large layer spacing, have been regarded as promising candidates as anode materials for sodium-ion batteries (SIBs). However, their low conductivity and large volume change during charge-discharge cycles leads to performance degradation. Herein, polyvinylpyrrolidone (PVP) is used as a soft template to synthesize PVP-derived nitrogen-doped carbon-coated MoS2 composites (MoS2/NC) by a simple hydrothermal method followed by high-temperature treatment. The as-prepared composite exhibits a flowerball-like morphology and a diameter of approximately 250 nm. The optimized MoS2/NC has the most uniform particle size and provides the best performance, with a stable capacity of 504.9 mAh g−1 after 120 cycles at a current density of 100 mA g−1. It has excellent rate performance, which can reach 524.6, 481.9, 447.7, 412.5, and 370.9 mAh g−1 at current densities of 0.1, 0.2, 0.5, 1 and 2 A g−1, respectively. The small particle size and the addition of carbonaceous materials play an important role in their excellent electrochemical properties. This study opens up a simple and effective way to synthesize high-performance two-dimensional MoS2 composite anodes for SIBs.