Double-shelled silicon anode nanocomposite materials: A facile approach for stabilizing electrochemical performance via interface construction

Abstract

The rapid capacity fading induced by volumetric changes is the main issue that hinders the widespread application of silicon anode materials. Thus, double-shelled silicon composite materials where lithium silicate was located between an Nb2O5 coating layer and a silicon active core were configured to overcome the chemical compatibility issues related to silicon and oxides. The proposed composites were prepared via a facile co-precipitation method combined with calcination. Transmission electron microscopy and X-ray photoelectron spectroscopy analysis demonstrated that a transition layer of lithium silicate was constructed successfully, which effectively hindered the thermal inter-diffusion between the silicon and oxide coating layers during heat treatment. The electrochemical performance of the double-shelled silicon composites was enhanced dramatically with a retained specific capacity of 1030 mAh g−1 after 200 cycles at a current density of 200 mA g−1 compared with 598 mAh g−1 for a core-shell Si@Nb2O5 composite that lacked the interface. The lithium silicate transition layer was shown to play an important role in maintaining the high electrochemical stability.