Engineering hollow carbon black-confined nano-silicon architectures for high-capacity and long-life lithium-ion battery anodes

High-capacity Si alloy-based anodes undergo large volume expansion during cycling, necessitating new approaches to extend battery life. Various research focuses on securing the sub-nano size of Si particles. However, Si volume expansion during the lithiation process, remains a challenging problem. Herein, we employ nano-sized Si in a hollow structure with a mesopore-rich pore structure, emphasizing its role as an effective spacer for accommodating volume expansion during cycling. Hollow carbon black (HCB), which has a mesopore-rich pore structure, is produced by carbon black (CB) based on the mild oxidation method. Silane gas was employed to successfully incorporate Si into the backbone of HCB, forming nano-sized Si. HCB derived from CB not only enhances the electrical conductivity of the anode's active material but also serves as an efficient spacer to mitigate Si volume expansion during cycling. Remarkably, the synergy of nano-sized Si and the HCB demonstrates dramatic electrochemical performance in the Si anode. Notably, the optimized electrode delivered an initial discharge capacity of 2091.66 mAh g⁻¹ with an initial coulombic efficiency of 80.6 % and maintained 72.2 % of its capacity after 100 cycles, representing an improvement of approximately 10 %p in both initial coulombic efficiency and capacity retention compared with commercial nano Si. Along these lines, this report outlines a practical path for designing new high-capacity Si alloy-based anode materials for high-performance lithium-ion batteries.