Synergistic Integration of Carbon Nanotubes and Vertically Aligned Graphene Enables Silicon as Stable and High‐Rate Anodes in Lithium‐Ion Batteries

As the demand for high‐energy‐density lithium‐ion batteries grows, research increasingly focuses on high‐capacity anode materials to substitute low‐capacity graphite. Silicon is a promising, high‐theoretical‐capacity (4200 mAh g −1 ) anode material. However, suffering from severe volumetric expansion (≈400%) and poor conductivity (≈10 −5 S cm −1 ), the silicon anode shows unsatisfactory cycling stability and rate performance. Here, a 3D interconnected conductive and porous carbon network is constructed by self‐assembling carbon nanotubes onto silicon nanoparticles encapsulated in vertically aligned graphene through the spray drying method. The carbon network provides efficient space, accommodating volumetric expansion of Si. Vertical graphene provides directional ion transportation and carbon nanotubes accelerate the electron transfer due to their high conductivity. The collaboration constructs a 3D robust conductive network to boost charge transport throughout the electrode. With these structural advantages, the electrodes deliver high capacities of 904 mAhg −1 at 5 Ag −1 with high capacity retention of 78.0% after 1000 cycles and 418 mAhg −1 at 20 Ag −1 , while exhibiting only a 2.6% thickness change in the cross‐sectional direction after 100 cycles at 0.5 Ag −1 . Furthermore, the lithium storage mechanism of the silicon–carbon anode is elucidated through cyclic voltammetry and ex situ X‐ray diffraction.