Construction of Structure-Tunable Si@Void@C Anode Materials for Lithium-Ion Batteries through Controlling the Growth Kinetics of Resin

Silicon (Si), a promising candidate for next-generation lithium-ion battery anodes, is still hindered by its volume change issue for (de)lithiation, thus resulting in tremendous capacity fading. Designing carbon-modified Si materials with a void-preserving structure (Si@void@C) can effectively solve this issue. The preparation of Si@void@C, however, usually depended on template-based routes or chemical vapor deposition, which involve toxic reagents, tedious operation processes, and harsh conditions. Here, a facile templateless approach for preparing Si@void@C materials is reported through controlling the growth kinetics of resin, without the use of toxic hydrofluoric acid or harsh conditions. This approach allows great flexibility in tuning the crucial parameters of Si@void@C, such as the carbon shell thickness, the reserved void size, and the number of Si cores coated by a carbon shell. The optimized Si@void@C delivers a large specific capacity (1993.2 mAh g^-1 at 0.1 A g^-1), excellent rate performance (799.4 mAh g^-1 at 10.0 A g^-1), and long cycle life (73.5% capacity retention after 1000 cycles at 2.0 A g^-1). In addition, a full cell fabricated with a Si@void@C anode and commercial LiFePO₄ cathode also displays an impressive cycling performance.