Introducing SiC/C dual-interface on porous silicon anode by a conventional exothermic displacement reaction for improved cycle performance

Abstract

The poor cyclability and high cost are the two major obstacles to the commercial applications of Si-based anode materials. Porous structure and carbon coating may facilitate the ion and electron conduction and also restrict the huge volume change of Si anodes. In addition, introducing a ceramic interlayer between Si and C can reduce the chemical reaction of Si with fluorine ions in the electrolyte and hence improve the cyclability. In this work, porous Si anode protected by SiC/C dual-interface is prepared by simply heating fine Mg 2 Si particles in pure CO 2 at 650 °C, based on the conventional exothermic displacement reaction between Mg (released from Mg 2 Si) and CO 2 . The large amount of heat generated during the displacement reaction leads to sharp temperature rise, resulting in the formation of SiC at such a low temperature. The porous Si/SiC/C powders as well as the spherical sample prepared by subsequent spray-drying and pyrolysis process display much improved rate capability and cyclability as compared to the porous Si/C counterpart, due to the enhanced structural integrity induced synergistically by the porous structure, SiC/C dual-interface and spherical structure during the repeated lithiation/delithiation cycles. • SiC/C dual-interface is introduced on porous Si anode at low temperature. • Fine Mg 2 Si leads to high exothermic displacement reaction between Mg and CO 2 . • Porous SiC/C/Si anode exhibits improved rate capability and cyclstability. • Spherical porous SiC/C/Si anode shows the least volume expansion after cycles.