Interlayer-Expanded MoS Enabled by Sandwiched Monolayer Carbon for High Performance Potassium Storage.

Potassium-ion batteries (PIBs) have aroused a large amount of interest recently due to the plentiful potassium resource, which may show cost benefits over lithium-ion batteries (LIBs). However, the huge volume expansion induced by the intercalation of large-sized potassium ions and the intrinsic sluggish kinetics of the anode hamper the application of PIBs. Herein, by rational design, nano-roses assembled from petals with a MoS/monolayer carbon (C-MoS) sandwiched structure were successfully synthesized. The interlayer distance of ultrathin C-MoS was expanded from original MoS of 6.2 to 9.6 Å due to the formation of the MoS-carbon inter overlapped superstructure. This unique structure efficiently alleviates the mechanical strain, prevents the aggregation of MoS, creates more active sites, facilitates electron transport, and enhances the specific capacity and K diffusion kinetics. As a result, the prepared C-MoS-1 anode delivers a high reversible specific capacity (437 mAh g at 0.1 A g) and satisfying rate performance (123 mAh g at 6.4 A g). Therefore, this work provides new insights into the design of high-performance anode materials of PIBs.