Facile Spray-Drying Synthesis of Dual-Shell Structure Si@SiOx@Graphite/Graphene as Stable Anode for Li-Ion Batteries

A dual-shell structure Si@SiOx@graphite/graphene (SGGr) is prepared by large-scale spray-drying. In this composite, Si nanoparticles act as the core, SiOx and graphite/graphene serve as the shell. Transmission electron microscopy (TEM) studies show that Si nanoparticles are coated with a 1-2 nm SiOx layer and embedded into the sheets of graphite/graphene. Amorphous SiOx and graphite/graphene as the production layer can prevent Si directly connecting with the electrolyte and improve the entire structural stability. In addition, nitrogen adsorption-desorption measurements indicate that the prepared SGGr has a higher Brunauer-Emmett-Teller (BET) surface area (48.4 m(2) g(-1)) than pure Si (36.2 m(2) g(-1)) due to the existence of mesopores and macropores, which can shorten the lithium-ion transport pathway and provide enough void space for accommodating the volume expansion. The prepared SGGr exhibits a high reversible specific capacity of 1089.3 mAh g(-1) after 400 cycles (0.16% decay per cycle), indicating that SGGr has the great potential for industrial application for lithium-ion batteries.