Mesoporous carbon shell encapsulated silicon/graphite composite with two-dimensional conductive networks and self-adaptive spacing for enhanced lithium-ion storage performance

Although silicon (Si) is widely recognized as one of the most promising anode materials for next-generation lithium-ion batteries (LIBs), its severe volume expansion and poor electrical conductivity pose significant challenges for commercialization. To address these challenges, a mesoporous carbon shell encapsulated silicon/graphite composite (Si/G@PCS) with distinctive two-dimensional conductive network and self-adaptive internal spacing was deliberately designed in this work. Silicon nanoparticles (Si NPs) were uniformly dispersed on graphite sheets through ball milling to create a highly efficient conductive network, which were further entirely encapsulated by a nanoporous carbon shell via pyrolysis, forming a capsule-like core-shell structure. The integration of assembled graphite nanosheets featuring abundant internal voids spacing could significantly improve the electrical conductivity of Si NPs while effectively mitigate the lithiation associated volume expansion. Moreover, the abundant mesopores on the outer carbon shell provided rapid ion transport pathways, thereby enhancing the anode's overall electrochemical performance. The prepared Si/G@PCS electrode exhibited a high initial coulombic efficiency (ICE) of 80.65 % during the first cycle. After 100 cycles at a current density of 0.2 A g −1 , the electrode retained a reversible capacity of up to 971.5 mAh g −1 . Notably, even at a higher current density of 2 A g −1 , it still delivered a capacity of 711.5 mAh g −1 . The rational design and preparation for Si/G@PCS composite proposed in this study provides a feasible strategy for the large-scale preparation of high-energy-density silicon anode materials.