title: 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.
authors: Electron Microscopy Laboratory, School of Physics, Peking University , Beijing 100871, China.|Collaborative Innovation Center of Quantum Matter, Beijing 100871, China.
authors: Peng
authors: P
authors: Gao
authors: State Key Laboratory of Electronic Thin Films and Integrated Devices, University of Electronic Science and Technology of China , Chengdu 610054, China.
authors: Liping
authors: L
authors: Wang
authors: Institute of Physics, Chinese Academy of Sciences , Beijing 100190, China.
authors: Yu-Yang
authors: YY
authors: Zhang
authors: Brookhaven National Laboratory , Upton, New York 11973, United States.
authors: Yuan
authors: Y
authors: Huang
authors: Department of Physics and Key Laboratory of Artificial Micro- and Nano-structures of Ministry of Education, Wuhan University , Wuhan 430072, China.
authors: Lei
authors: L
authors: Liao
authors: Department of Electrical and Computer Engineering, University of Nebraska-Lincoln , Lincoln, Nebraska 68588, United States.
authors: Peter
authors: P
authors: Sutter
authors: Collaborative Innovation Center of Quantum Matter, Beijing 100871, China.|State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University , Beijing 100871, China.
authors: Kaihui
authors: K
authors: Liu
authors: Collaborative Innovation Center of Quantum Matter, Beijing 100871, China.|State Key Laboratory for Mesoscopic Physics, School of Physics, Peking University , Beijing 100871, China.
authors: Dapeng
authors: D
authors: Yu
authors: Collaborative Innovation Center of Quantum Matter, Beijing 100871, China.|International Center for Quantum Materials, School of Physics, Peking University , Beijing 100871, China.
authors: En-Ge
authors: EG
authors: Wang
keywords: Lithium ion battery; electrochemistry dynamics; first-principles calculation; in situ TEM; intermediate phase