High-Resolution Tracking Asymmetric Lithium Insertion and Extraction and Local Structure Ordering in SnS₂

Abstract

In the rechargeable lithium ion batteries, the rate capability and energy efficiency are largely governed by the lithium ion transport dynamics and phase transition pathways in electrodes. Real-time and atomic-scale tracking of fully reversible lithium insertion and extraction processes in electrodes, which would ultimately lead to mechanistic understanding of how the electrodes function and why they fail, is highly desirable but very challenging. Here, we track lithium insertion and extraction in the van der Waals interactions dominated SnS2 by in situ high-resolution TEM method. We find that the lithium insertion occurs via a fast two-phase reaction to form expanded and defective LiSnS2, while the lithium extraction initially involves heterogeneous nucleation of intermediate superstructure Li0.5SnS2 domains with a 1-4 nm size. Density functional theory calculations indicate that the Li0.5SnS2 is kinetically favored and structurally stable. The asymmetric reaction pathways may supply enlightening insights into the mechanistic understanding of the underlying electrochemistry in the layered electrode materials and also suggest possible alternatives to the accepted explanation of the origins of voltage hysteresis in the intercalation electrode materials.

Orientation‐Dependent Intercalation Channels for Lithium and Sodium in Black Phosphorus

“…[27] This value is close to the Li diffusion coefficient of other 2D layered materials calculated by in situ TEM observations. [27] This value is close to the Li diffusion coefficient of other 2D layered materials calculated by in situ TEM observations.…”

“…The theoretical specific ion storage capacity for Li-ion batteries (LIBs) and Na-ion batteries (NIBs) can be as high as 2596 mAh g −1 , which is almost one order of magnitude higher than the commercial graphite-based materials (372 mAh g −1 ), holding great promise for future applications ranging from portable electronic devices to large-scale electrical vehicles and power tools. Specifically, a great effort has been devoted to the intercalation of lithium and sodium in a large variety of 2D materials, including graphite, [17,18] borophane, [19] transition metal dichalcogenides, [20][21][22][23] transition metal carbides/carbonitrides, [24,25] and tin-based compounds, [26][27][28] which have larger interlayer spacing bonded by vdW interaction to offer sufficient ionic transport pathway. To bridge up this knowledge gap, we present an in situ investigation on the intercalation of BP with both lithium and sodium ions.…”

“…Specifically, a great effort has been devoted to the intercalation of lithium and sodium in a large variety of 2D materials, including graphite, [17,18] borophane, [19] transition metal dichalcogenides, [20][21][22][23] transition metal carbides/carbonitrides, [24,25] and tin-based compounds, [26][27][28] which have larger interlayer spacing bonded by vdW interaction to offer sufficient ionic transport pathway. Specifically, a great effort has been devoted to the intercalation of lithium and sodium in a large variety of 2D materials, including graphite, [17,18] borophane, [19] transition metal dichalcogenides, [20][21][22][23] transition metal carbides/carbonitrides, [24,25] and tin-based compounds, [26][27][28] which have larger interlayer spacing bonded by vdW interaction to offer sufficient ionic transport pathway.…”

Review—Promises and Challenges of In Situ Transmission Electron Microscopy Electrochemical Techniques in the Studies of Lithium Ion Batteries

“…14,55,[183][184][185][186] Pulverization is one of the most undesirable factors result in capacity fading and instability in cycling for Sn-based anode in LIBs. 183 The β-Sn NPs in the size range from 79 to 526 nm converted to crystal Li 22 Sn 5 phase without cracking or fracture after lithiation, but upon lithiation these NPs in this range of sizes could be induced and to form micrometer-sized Sn NPs where fractures were frequently observed.…”

Unveiling the Unique Phase Transformation Behavior and Sodiation Kinetics of 1D van der Waals Sb2S3 Anodes for Sodium Ion Batteries

“…Compared with other popular characterization methods, like ex situ or in situ X-ray diffraction (XRD) analysis, [29,30] Mössbauer spectroscopy [31] and nuclear magnetic resonance, [32] the thriving in situ TEM and the associated selected area electron diffraction (SAED) analysis have relatively higher spatial and temporal resolutions to directly track in real time the local and/or intermediate phases. According to the reaction mechanisms in the other van der Waals stacked materials, such as SnS 2 [33] and MoS 2 , [38,39] the intercalation of Li + /Na + ions consisted of obvious twophase reaction behaviors leading to the formation of crystalline phases, i.e., LiSnS 2 , 1T-LiMoS 2 , and NaMoS 2 , at a constant stoichiometric ratio. At the very beginning, the Na + ions intercalate into the crystalline Sb 2 S 3 phase at an ultrafast speed to form amorphous Na x Sb 2 S 3 (x < 12) intermediate phases with an accompanied small volume expansion of ≈54%.…”