Applying surface coatings to alloying anodes for Li-ion batteries can improve rate capability and cycle life, but it is unclear how this second phase affects mechanical deformation during electrochemical reaction. Here, in-situ transmission electron microscopy is employed to investigate the electrochemical lithiation and delithiation of silicon nanowires (NWs) with copper coatings. When copper is coated on only one sidewall, the NW bilayer structure bends during delithiation due to length changes in the silicon. Tensile hoop stress causes conformal copper coatings to fracture during lithiation without undergoing bending deformation. In addition, in-situ and ex-situ observations indicate that a copper coating plays a role in suppressing volume expansion during lithiation. Finally, the deformation characteristics and dimensional changes of amorphous, polycrystalline, and single-crystalline silicon are compared and related to observed electrochemical behavior. This study reveals important aspects of the deformation process of silicon anodes, and the results suggest that metallic coatings can be used to improve rate behavior and to manage or direct volume expansion in optimized silicon anode frameworks. © 2012 Elsevier Ltd.
Bibliographical noteKAUST Repository Item: Exported on 2020-10-01
Acknowledged KAUST grant number(s): KUSH L1-001-12, KUK-F1-038-02
Acknowledgements: Portions of this work are supported by the U.S. Department of Energy, Office of Basic Energy Sciences, Division of Materials Sciences and Engineering under Contract no. DE-AC02-76SF00515 through the SLAC National Accelerator Laboratory LDRD project and the Assistant Secretary for Energy efficiency and Renewable Energy, Office of Vehicle Technologies of the U.S. Department of Energy under Contract no. DE-AC02-05CH11231, Subcontract no. 6951379 under the Batteries for Advanced Transportation Technologies (BATT) Program. Y.C. acknowledges support from the King Abdullah University of Science and Technology (KAUST) Investigator Award (no. KUSH L1-001-12). M.T.M. acknowledges support from the Chevron Stanford Graduate Fellowship, the National Defense Science and Engineering Graduate Fellowship, and the National Science Foundation Graduate Fellowship. S.W.L. acknowledges support from KAUST (no. KUK-F1-038-02). C.M.W. acknowledges support from the Laboratory Directed Research and Development (LDRD) program of Pacific Northwest National Laboratory. The in-situ TEM work was conducted in the William R. Wiley Environmental Molecular Sciences Laboratory (EMSL), a national scientific user facility sponsored by DOE's Office of Biological and Environmental Research and located at PNNL. PNNL is operated by Battelle for the DOE under Contract DE-AC05-76RLO1830.
This publication acknowledges KAUST support, but has no KAUST affiliated authors.