Nanocaging Silicon Nanoparticles into a Porous Carbon Framework toward Enhanced Lithium-Ion Storage

Silicon (Si) shows overwhelming promise as the high-capacity anode material of Li-ion batteries with high energy density. However, Si-based anodes are subjected to a limited electrochemical cycling lifetime due to their large volume change. Herein, a honeycomb-like biomass-derived carbon nanosheet framework is reported to encapsulate Si nanoparticles via a facile molten salt templating method. The carbon framework provides sufficient void space for effectively accommodating the large volume expansion of Si upon Li⁺ insertion. Moreover, the interconnected carbon skeletons afford fast electron/ion transport pathways for improving the reaction kinetics. Consequently, the porous Si/carbon composite could exhibit a high and stable Li storage capacity of 1022 mAh g⁻¹ at 0.2 A g⁻¹ over 100 cycles along with superior rate capability (555 mAh g⁻¹ at 5 A g⁻¹). This study demonstrates an effective structural design strategy for Si-based anodes toward stable lithium energy storage.