@article{dab2ace2de7b4c22b4ce2b4cfd7f2949,
title = "Kinetically-Driven Phase Transformation during Lithiation in Copper Sulfide Nanoflakes",
abstract = "Two-dimensional (2D) transition metal chalcogenides have been widely studied and utilized as electrode materials for lithium ion batteries due to their unique layered structures to accommodate reversible lithium insertion. Real-time observation and mechanistic understanding of the phase transformations during lithiation of these materials are critically important for improving battery performance by controlling structures and reaction pathways. Here, we use in situ transmission electron microscopy methods to study the structural, morphological, and chemical evolutions in individual copper sulfide (CuS) nanoflakes during lithiation. We report a highly kinetically driven phase transformation in which lithium ions rapidly intercalate into the 2D van der Waals-stacked interlayers in the initial stage, and further lithiation induces the Cu extrusion via a displacement reaction mechanism that is different from the typical conversion reactions. Density functional theory calculations have confirmed both the thermodynamically favored and the kinetically driven reaction pathways. Our findings elucidate the reaction pathways of the Li/CuS system under nonequilibrium conditions and provide valuable insight into the atomistic lithiation mechanisms of transition metal sulfides in general.",
keywords = "Copper sulfides, CuS, electrochemistry kinetics, in situ TEM, lithium ion battery",
author = "Kai He and Zhenpeng Yao and Sooyeon Hwang and Na Li and Ke Sun and Hong Gan and Yaping Du and Hua Zhang and Chris Wolverton and Dong Su",
note = "Funding Information: We acknowledge the support of the Center for Functional Nanomaterials, Brookhaven National Laboratory, which is supported by the U.S. Department of Energy (DOE), Office of Basic Energy Sciences under Contract No. DE-SC-00112704. Z.Y. and C.W. were supported as part of the Center for Electrochemical Energy Science (CEES), an Energy Frontier Research Center funded by the U.S. DOE, Office of Science, Basic Energy Sciences under Award No. DEAC02-06CH11357. K.S. and H.G. were supported by U.S. DOE Office of Energy Efficiency and Renewable Energy under the Advanced Battery Materials Research (BMR) program, Contract No. DE-SC0012704. We gratefully acknowledge the computing resources from (1) the National Energy Research Scientific Computing Center, a DOE Office of Science User Facility supported by the Office of Science of the U.S. DOE under Contract No. DE-AC02-05CH11231, and (2) Blues, a high-performance computing cluster operated by the Laboratory Computing Resource Center at Argonne National Laboratory. K.H. would like to thank the support of the NUANCE Center, which has received support from the Soft and Hybrid Nanotechnology Experimental (SHyNE) Resource (NSF ECCS-1542205); the MRSEC program (NSF DMR-1121262) at the Materials Research Center; the International Institute for Nanotechnology (IIN); the Keck Foundation; and the State of Illinois, through the IIN. H.Z. would like to acknowledge the Facility for Analysis, Characterization, Testing, and Simulation, Nanyang Technological University, Singapore, for use of their electron microscopy facilities. Publisher Copyright: {\textcopyright} 2017 American Chemical Society.",
year = "2017",
month = sep,
day = "13",
doi = "10.1021/acs.nanolett.7b02694",
language = "English (US)",
volume = "17",
pages = "5726--5733",
journal = "Nano Letters",
issn = "1530-6984",
publisher = "American Chemical Society",
number = "9",
}
