Atomic‐Level Regulation of SiC₄ Units Enable High Li⁺ Dynamics and Long‐Life Micro‐Size SiC_x 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 SiH₄ and C₂H₄ 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 SiC₄ tetrahedra in SiC_x plays a key role in particles’ microstructure optimization and electrochemical performance improvement: 1) The SiC₄‐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 SiC₄ 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.