Grant Williamson1 Elena Pandres1 Vincent Holmberg1

1, University of Washington, Seattle, Washington, United States

Antimony is one of the most promising high-rate-capability Na- and Li-ion conversion electrode materials, demonstrating extraordinarily high rates of lithiation and sodiation, with small isotropic Sb nanocrystals exhibiting stable, reversible, long-term cycling at charge/discharge rates as fast as 20C without significant capacity loss. Herein, we investigate the effect of structural anisotropy on the lithiation and sodiation of high-capacity, high-power density Sb alloying electrodes fabricated from an engineered set of highly anisotropic Sb nanostructures recently developed by our laboratory. To our knowledge, none of these anisotropic structures have been previously reported in the literature, or evaluated as alloying electrode materials. In addition to describing the supercritical fluid-based synthesis of these anisotropic Sb nanostructures, we discuss how structural anisotropy, oxidation, and temperature influence the electrochemical alloying process, with an overarching goal of better understanding the transformations that take place during the high-rate electrochemical alloying of nanostructured antimony.