Si-based materials are the promising anode candidates for the next generation lithium-ion battery. However, the poor cycle performance has hindered their practical applications. Herein, a fresh and fundamental reason for the rapid capacity decay of silicon-based materials was proclaimed. Silicon can chemically react with LiPF₆ and generate Li₂SiF₆ aggregations constantly during cycling. Moreover, nano carbon on the surface of silicon acted as a catalyst to accelerate such detrimental reaction. Herein, taking advantage of high strength and toughness of SiC, SiC layer was rationally introduced between inner silicon and outer carbon to inhibit the chemical formation reaction of Li₂SiF₆. The side reaction rate reduced by 10 times than that of Si, and 300 times than that of Si@C, attributed to the increased activation energy of Li₂SiF₆ formation reaction. The Si@SiC@C maintained a specific capacity of 980 mAh g^-1 at the current density of 1 A g^-1 after 800 cycles with the initial Coulombic efficiency (ICE) over 88.5%. This work will shed fresh light on the degradation of Si-based materials and further guide the rational design of silicon structures for high-performance Si-based materials.