Atomic‐Level Regulation of SiC4 Units Enable High Li+ Dynamics and Long‐Life Micro‐Size SiCx Anodes

Abstract Large‐scale applications of high‐capacity silicon‐based anodes remain a challenge for high‐energy lithium‐ion batteries (LIBs) owing to huge volume variation. Although designing nano‐sized Silicon (Si) anodes plays a milestone advance in the commercial development, it's still hindered by issues related to cost and side reactions. A simple co‐pyrolysis of SiH 4 and C 2 H 4 is introduced via chemical‐vapor‐deposition (CVD) method to prepare SiC x micro‐sized particles with atomic‐level homogeneous distributions of silicon and carbon. One basic unit of SiC 4 tetrahedra in SiC x plays a key role in particles’ microstructure optimization and electrochemical performance improvement: 1) The SiC 4 ‐enriched surface layer is found to hinder Li + insertion. 2) Proper heat‐treatment temperature is adopted to eliminate the layer and control the transition from SiC 4 to SiC nanocrystalline, which is significant for decreasing polarization, enhancing Li + diffusion kinetics, and cycling stability. Consequently, the optimized architecture exhibits a high capacity of 1455 mA h g −1 with an outstanding capacity retention of 95.8% after 100 cycles. Pouch‐type full‐cell demonstrates that the composite possesses excellent cycling stability with capacity retentions of 82.5% after 500 cycles at 25 °C and 84.0% after 400 cycles at 45 °C. This work provides a scalable yet practical solution to micro‐sized Si‐based anodes.