title: Surface-coating regulated lithiation kinetics and degradation in silicon nanowires for lithium ion battery.
abstract: Silicon (Si)-based materials hold promise as the next-generation anodes for high-energy lithium (Li)-ion batteries. Enormous research efforts have been undertaken to mitigate the chemo-mechanical failure due to the large volume changes of Si during lithiation and delithiation cycles. It has been found that nanostructured Si coated with carbon or other functional materials can lead to significantly improved cyclability. However, the underlying mechanism and comparative performance of different coatings remain poorly understood. Herein, using in situ transmission electron microscopy (TEM) through a nanoscale half-cell battery, in combination with chemo-mechanical simulation, we explored the effect of thin (∼5 nm) alucone and Al2O3 coatings on the lithiation kinetics of Si nanowires (SiNWs). We observed that the alucone coating leads to a "V-shaped" lithiation front of the SiNWs, while the Al2O3 coating yields an "H-shaped" lithiation front. These observations indicate that the difference between the Li surface diffusivity and bulk lithiation rate of the coatings dictates lithiation induced morphological evolution in the nanowires. Our experiments also indicate that the reaction rate in the coating layer can be the limiting step for lithiation and therefore critically influences the rate performance of the battery. Further, the failure mechanism of the Al2O3 coated SiNWs was also explored. Our studies shed light on the design of high capacity, high rate and long cycle life Li-ion batteries.
authors.affiliation: †Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99352, United States.
authors.forename: Langli
authors.initials: L
authors.lastname: Luo
authors.affiliation: ‡Engineering Science and Mechanics and Bioengineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States.
authors.forename: Hui
authors.initials: H
authors.lastname: Yang
authors.affiliation: †Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99352, United States.
authors.forename: Pengfei
authors.initials: P
authors.lastname: Yan
authors.affiliation: §University of Colorado at Boulder, Boulder, Colorado 80309, United States.
authors.forename: Jonathan J
authors.initials: JJ
authors.lastname: Travis
authors.affiliation: §University of Colorado at Boulder, Boulder, Colorado 80309, United States.
authors.forename: Younghee
authors.initials: Y
authors.lastname: Lee
authors.affiliation: ∥Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States.
authors.forename: Nian
authors.initials: N
authors.lastname: Liu
authors.affiliation: §University of Colorado at Boulder, Boulder, Colorado 80309, United States.
authors.forename: Daniela Molina
authors.initials: DM
authors.lastname: Piper
authors.affiliation: §University of Colorado at Boulder, Boulder, Colorado 80309, United States.
authors.forename: Se-Hee
authors.initials: SH
authors.lastname: Lee
authors.affiliation: ‡Engineering Science and Mechanics and Bioengineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States.
authors.forename: Peng
authors.initials: P
authors.lastname: Zhao
authors.affiliation: §University of Colorado at Boulder, Boulder, Colorado 80309, United States.
authors.forename: Steven M
authors.initials: SM
authors.lastname: George
authors.affiliation: ⊥Energy and Environmental Directorate, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99352, United States.
authors.forename: Ji-Guang
authors.initials: JG
authors.lastname: Zhang
authors.affiliation: ∥Department of Materials Science and Engineering, Stanford University, Stanford, California 94305, United States.|#Stanford Institute for Materials and Energy Sciences, SLAC National Accelerator Laboratory, 2575 Sand Hill Road, Menlo Park, California 94025, United States.
authors.forename: Yi
authors.initials: Y
authors.lastname: Cui
authors.affiliation: ‡Engineering Science and Mechanics and Bioengineering, Pennsylvania State University, University Park, Pennsylvania 16802, United States.
authors.forename: Sulin
authors.initials: S
authors.lastname: Zhang
authors.affiliation: ∇National Renewable Energy Laboratory, 1617 Cole Boulevard, Golden, Colorado 80401, United States.
authors.forename: Chunmei
authors.initials: C
authors.lastname: Ban
authors.affiliation: †Environmental Molecular Sciences Laboratory, Pacific Northwest National Laboratory, 902 Battelle Boulevard, Richland, Washington 99352, United States.
authors.forename: Chong-Min
authors.initials: CM
authors.lastname: Wang
keywords: Silicon nanowire; in situ TEM; lithium ion battery; surface coating