Three-Dimensional Crosslinked CNT/SiO x -F Network Encapsulated by Pitch-Derived Carbon as a High-Stable Anode for Lithium-Ion Batteries

Intrinsic low conductivity and huge volume expansion severely limit the cycling stability of SiOx anodes. Herein, a 3D crosslinked CNT/SiOx-F@C composite is synthesized via bifunctional fluorosilane crosslinkers and conformal pitch carbon coating. Fluorosilane acts as both a silicon source and a crosslinker to build interconnected, conductive CNT frameworks, while the outer pitch carbon optimizes the pore structure and induces flexible, LixPOyF6-rich SEI layers. Kinetic tests reveal dominant capacitive charge storage and a Li+ diffusion coefficient one-order-of-magnitude higher than that of control electrodes. The half-cell delivers a stable reversible capacity of 672.6 mA h g–1 over 200 cycles at 0.2 A g–1 and retains 86.5% capacity after 600 cycles at 1 A g–1. Pre-lithiation elevates the initial Coulombic efficiency from 47.4 to 84.2%, while the electrode achieves an areal capacity approaching 4 mA h cm–2, far exceeding that of commercial graphite. This dual-carbon synergistic strategy provides a facile route to optimizing silicon oxide anodes.