Nanorod‐Structured SiC Composites for Enhanced Ionic Conductivity and Volume Expansion Mitigation in Lithium‐Ion Batteries

Silicon anodes suffer from severe volume expansion during cycling, limiting their practical application in lithium‐ion batteries. In this study, SiC composites with distinct particle morphologies were prepared by controlling the cooling process following magnesiothermic reduction, producing nanoparticle‐aggregated SiC (SiC‐NP) and an interconnected SiC nanorod network (SiC‐NR). Although both composites exhibited similar phase compositions, the SiC‐NR electrode showed markedly improved initial Coulombic efficiency, cycling stability, and rate capability. EIS and GITT analyses revealed that SiC‐NR exhibited lower interfacial resistance, higher Li + diffusion coefficients, and reduced tortuosity, indicating more efficient ion transport through the nanorod‐based architecture. In situ electrochemical dilatometry and cross‐sectional SEM further demonstrated that SiC‐NR undergoes significantly smaller electrode thickness expansion during cycling (55.0% vs. 108.9% for SiC‐NP after 100 cycles), reflecting enhanced structural stability against lithiation‐induced volume changes. These results suggest that the interconnected nanorod architecture of the SiC composite contributes to improved ion transport, relatively stable interphase evolution, and suppressed electrode expansion, highlighting an effective structural design strategy for durable silicon‐based anodes.