Ultrahigh Malleability of the Lithiation-Induced LixSi Phase

Through in situ transmission electron microscopy (TEM) observation, the lithiation behaviors of carbon-coated silicon (Si) nanostructures are investigated. Our experimental results reveal that the carbon (C) coating can not only mediate the lithiation kinetics and volume expansion, leading to the retardation or even complete suppression of the lithiation process, but also determine the morphological evolution and final shape of the lithiation products. The lithiation behaviors of C-coated Si nanostructures are further corroborated by chemo-mechanical simulations. Our study consistently demonstrates that the effect of C coating layer on the lithiation behaviors of Si nanostructures is closely related to the ultrahigh malleability and deformability of the lithiation-induced Li x Si phase. The finding of this study sheds light on the rational design of high-performance Si–C composite electrode materials.