Construction of hierarchical NiS@C/rGO heterostructures for enhanced sodium storage

Abstract

Transition metal sulfides have attracted considerable interest as anode for sodium ion batteries (SIBs) in view of their high theoretical capacity and decent redox reversibility. However, their practical application is hindered by the low intrinsic conductivity and large volume effects during the conversion-type sodiation/desodiation process, which remain great challenges for achieving high performance SIBs. Nanostructure engineering and carbon hybridization have been reported as effective strategies for constructing advanced electrode materials with enhanced electrochemical properties. Herein, we report the designed synthesis of a multilevel-carbon supported NiS anode material (NiS@C/rGO) with a complex hierarchical hollow structure via a simple hydrothermal-heat treatment method. With the compositional and structural merits, the prepared NiS@C/rGO anode manifests excellent sodium storage performance in terms of high reversible specific capacity (472.3 mAh g−1 at 0.1 A g−1), enhanced rate capability (324.1 mAh g−1 at 1 A g−1) and superior cycling stability 240.2 mAh g−1capacity retention after 500 cycles). The greatly improved electrochemical performance of NiS@C/rGO demonstrates the importance of electrode engineering by coupling multilevel carbon modification and hierarchical structure design for SIBs.