Controlled scalable synthesis of yolk-shell structured large-size industrial silicon with interconnected carbon network for lithium storage

Abstract

Yolk-shell structured nano-Si@void@C can greatly improve the electrical conductivity and buffer the large volume change of silicon nanoparticles, whereas inter poor electrical connection between Si cores and carbon shells still limits the lithium storage performance. Besides, it usually requires complex synthesis conditions and expensive nano-level silicon sources. Herein, we succeed in making the large-size industrial silicon (ca. 400–500 nm) to a yolk-shell structure with a controllable space buffer layer. Most importantly, an interconnected porous carbon network deriving from the thermal decomposition of carbon chains in silicon sources is formed within the carbon shell simultaneously, which can improve the electrical contact between Si cores and hollow carbon shells and prevent the active particles exposure to the electrolyte. With the help of static outer thin carbon shell, optimized inner void and the flexible electrically conductive carbon network, such yolk-shell structured Si@void@C submicron particles synthesizing by one-step carbon-coating procedure exhibit high initial coulomb efficiency of 62%, good rate performance, and excellent long cycling stability with 950.7 mAh g−1 at 100 mA g−1 after 100 cycles. The low consumption and stable synthesis method make it feasible for large-scale fabrication of the yolk-shell structured Si/C composites as commercial anodes for energy storage.