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 LiNi0.8Co0.1Mn0.1O2 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.