Silicon Deposition on Three‐Dimensional Graphene Powder in an Aqueous Environment for Fast‐Charging and Ultra‐Long Cycle Life Anode in Lithium‐Ion Batteries

Porous silicon-carbon composites formed by depositing silicon on carbon effectively mitigate silicon lithiation induced expansion and hold great potential as next-generation anodes of lithium-ion batteries (LIBs). However, limited lithium-ion diffusion in CVD-derived crystalline silicon and the amorphous carbon matrix restricts their fast-charging performance. Here, a safe, scalable approach using hydroxylated three-dimensional vertical graphene (3D-VG) is proposed to "capture" silicon from the hydrolysis-reduction products of 3-aminopropyltrimethoxysilane, enabling amorphous silicon deposition in aqueous conditions. By tuning pH and temperature, the oxygen in the deposited silicon is removed, obtaining the material of silicon on 3D-VG (Si/3D-VG) with the initial Coulombic efficiency to 83.0% and reversible capacity to 1200.7 mAh g⁻¹. The 2D-3D hierarchical structure of 3D-VG provides efficient lithium-ion transport pathways and a low-strain characteristic (with a full-lithiation expansion rate of only 6.9%), endowing the Si/3D-VG with excellent high-rate capability (up to 20.0 C) and long cycling stability (77.9% capacity retention after 3000 cycles at 5.0 C). Additionally, the full cell assembled with LiNi_0.8Co_0.1Mn_0.1O₂ exhibits a high gravimetric energy density of 588.3 Wh kg⁻¹ and a volumetric energy density of 1340.2 Wh L⁻¹. This work provides an innovatively cheap, green, and scalable approach for the fabrication of porous silicon-carbon anodes for commercial LIBs.