In Situ Constructing MoS₂‐C Nanospheres as Advanced Anode for Sodium‐Ion Battery

Abstract

Striving for achievements of anode materials with excellent rate capability and long cycle life is a key to the commercial progress of sodium‐ion batteries. In the present work, we report a spherical MoS2‐C nanocomposite as anode for sodium‐ion batteries (SIBs) with high‐performance. The active materials were prepared via an in situ solvothermal reaction, in which carbon and MoS2 were simultaneously formed in one pot using toluene, acetone and ethanol as solvents. SEM results show that the controlled morphology has relative to the solvents, and the thermal gravimetric (TG) and Raman spectrum results indicated that the carbon was in situ formed. The MoS2‐C nano‐spheres were applied for sodium ion batteries. The results illustrate that MoS2‐C harvested from ethanol demonstrates the best electrochemical performances with long cycling stability (430 mA h g−1 after 100th cycles at 0.2 A g−1) and high rate capability (248 mA h g−1 at 5 A g−1). The superior properties of MoS2‐C nanocoposite benefits from several merits: (1) nanoscale size can short path of Na+ diffusion, enlarge electrode/electrolyte contact area, (2) sphere structure possesses good stress–strain relief during Na+ insertion/extraction reactions and consequently decreases huge volume variation, (3) the carbon in situ formed between MoS2 particles can improve the intrinsically poor electronic conductivity leading to higher rate capability. The novel MoS2‐C architectures provide a new avenue to fabricate carbon coupled with sulfides materials with excellent performances.

Size Effects in Sodium Ion Batteries

“…With the reduction of particle size, the ratio of surface/interface to volume increases significantly, which enhances the contact surface area between the active materials and electrolyte and thus promotes the exchange of Na ions. [72][73][74][75][76][77][78][79] Three kinds of Na 3 V 2 (PO 4 ) 3 (NVP) were synthesized by Chen et al through a hydrothermal assisted sol-gel method, including nano-NVP@C, NVP@C and pure NVP. The nano-NVP@C showed the smallest and uniform size about 40 nm.…”