Anisotropic Swelling and Fracture of Silicon Nanowires during Lithiation

We report direct observation of an unexpected anisotropic swelling of Si nanowires during lithiation against either a solid electrolyte with a lithium counter-electrode or a liquid electrolyte with a LiCoO(2) counter-electrode. Such anisotropic expansion is attributed to the interfacial processes of accommodating large volumetric strains at the lithiation reaction front that depend sensitively on the crystallographic orientation. This anisotropic swelling results in lithiated Si nanowires with a remarkable dumbbell-shaped cross section, which develops due to plastic flow and an ensuing necking instability that is induced by the tensile hoop stress buildup in the lithiated shell. The plasticity-driven…

• NS
  National Science Foundation
• UD
  U.S. Department of Energy
• CF
  Center for Integrated Nanotechnologies
• OO
  Office of Science
• NN
  National Nuclear Security Administration
• DO
  Division of Materials Research
• DO
  Division of Civil, Mechanical and Manufacturing Innovation
• BE
  Basic Energy Sciences
• LD
  Laboratory Directed Research and Development
• AF
  Air Force Office of Scientific Research
• SN
  Sandia National Laboratories
• EF
  Energy Frontier Research Centers