Interlayer Expanded SnS2 Anchored on Nitrogen-Doped Graphene Nanosheets with Enhanced Potassium Storage

Potassium-ion batteries (PIBs) are promising candidates to substitute lithium-ion batteries (LIBs) as large-scale energy storage devices. However, developing suitable anode materials is still a great challenge that has limited the anticipated application of PIBs. Herein, the interlayer expanded SnS2 nanocrystals anchored on nitrogen-doped graphene nanosheets (SnS2@NC) are synthesized following a facile one-step hydrothermal strategy. Relying on the exquisite nanostructure with larger interlayer spacing, the K+ ions diffusion and charge transfer will be accelerated. In addition, the intense coupling interaction between nitrogen-doped graphene nanosheets and SnS2 can endow a sturdy nanostructure, avoiding the collapse and aggregation of SnS2 nanocrystals upon cycling. Based on the above merits, the as-prepared SnS2@NC anode exhibits improved electrochemical performanc (desirable rate capability of 206.7 mAhg(-1) at 1000 mAg(-1) and advanced cyclic property of 262.5 mAhg(-1), while after 100 cycles at 500 mAg(-1)). More importantly, multistep reactions of K+ storage mechanism combining with intercalation, conversion and alloying reactions are clearly illustrated by combined in-situ XRD measurement and ex-situ TEM detection. This strategy of enhancing K+ storage performances has a great potential for other electrode materials.