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

Abstract

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 mAh g−1 at 1000 mA g−1 and advanced cyclic property of 262.5 mAh g−1, while after 100 cycles at 500 mA g−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.

Structural Engineering of SnS2 Encapsulated in Carbon Nanoboxes for High‐Performance Sodium/Potassium‐Ion Batteries Anodes

“…[23,31,32] Similarly, SnS 2 -based materials face more serious challenges of sluggish transfer of K + (radius of 1.38 Å, 81% larger than Li + ) and severe volume change during the cycling process. [33,34] Designing nanostructures with interior void space has become an effective strategy for confining electrode materials with high volume change like Si, Sn, P, and Sb, etc. [35][36][37][38][39][40][41] However, to the best of our knowledge, for modification of SnS 2based materials, very few researches of SnS 2 @void@C are reported.…”

“…[27] The peak at ≈0.51 V is ascribed to the combination of phase transition (from SnS 2 to K-Sn compounds and Sn) and the alloying of K and Sn. [33] As for the initial anodic sweep, the peaks at 0.98 and 1.44 V are assigned to the dealloying of K-Sn alloy and the depotassiation of K-S compounds. [34] The well overlapped profiles in the subsequent sweeps indicate good stability and reversibility of the electrode.…”

“…For the mechanism of K + storage process, previously reported works have illustrated the structural evolution via ex situ and in situ XRD measurements during patassiation/depotassiation. [12,24,27,33,34,62] However, the phase evolution of polysulfide, in spite of which gives a strong contribution to the capacity, still left weak point. In view of this, to further understand the K + storage process, in situ Raman spectra were performed to investigate the phase evolution of potassium polysulfide.…”

“…[ 23,31,32 ] Similarly, SnS 2 ‐based materials face more serious challenges of sluggish transfer of K + (radius of 1.38 Å, 81% larger than Li + ) and severe volume change during the cycling process. [ 33,34 ]…”

Metal Chalcogenides: Paving the Way for High‐Performance Sodium/Potassium‐Ion Batteries

“…SnS 2 . [59] Based on the in situ XRD analysis (Figure 18a,b), the authors postulated the charge storage mechanism as a sequential of intercalation, conversion and alloying reaction. The initial intercalation process turns SnS 2 into SnS and K 2 S followed a conversion reaction that lead to the formation of metallic Sn.…”