Interface-engineered MoS2/C nanosheet heterostructure arrays for ultra-stable sodium-ion batteries

Abstract

Development of ultra-stable high capacity electrodes is imperative for the widespread commercialization of sodium-ion batteries. Herein, we employed a micro-area etching and surface functionalization strategy to synthesize two-dimensional (2D) MoS2/C nanosheets with a well-defined heterointerface vertically anchored on a carbon cloth. The large MoS2/C nanosheet heterointerface and a high interlayer distance (0.99 nm) not only facilitated Na+ intercalation but also improved the diffusion kinetics of Na+ in the 2D interlayer space. A modulation of the cut-off voltage yielded a high specific capacity of 433 mAh g−1 at 0.2 A g−1 and 232 mAh g−1 at 10 A g−1 within the potential range of 0.4–3.0 V. These values are much higher than that of pure MoS2 nanosheet arrays (162 mAh g−1 at 10 A g−1). More importantly, during the first 1500 cycles, the capacity was maintained at ∼320 mAh g−1 at 1 A g−1, while after 10000 cycles, it became approximately ∼271 mAh g−1 at 3 A g−1. These are the best values ever reported for MoS2-based anode materials for SIBs. Furthermore, after being assembled into a flexible battery, it withstand repeated bending for over 200 times without any obvious capacity loss. Hence, this material is a promising electrode for future flexible batteries. © 2017 Elsevier Ltd