Novel Size and Surface Oxide Effects in Silicon Nanowires as Lithium Battery Anodes

With its high specific capacity, silicon is a promising anode material for high-energy lithium-ion batteries, but volume expansion and fracture during lithium reaction have prevented implementation. Si nanostructures have shown resistance to fracture during cycling, but the critical effects of nanostructure size and native surface oxide on volume expansion and cycling performance are not understood. Here, we use an ex situ transmission electron microscopy technique to observe the same Si nanowires before and after lithiation and have discovered the impacts of size and surface oxide on volume expansion. For nanowires with native SiO2, the surface oxide can suppress the volume expansion during lithiation for nanowires with diameters