Carbon Nanotube Film Expanded with Highly Lithiophilic MgF₂@VGCF Hybrid for Dendrite-Free Lithium Metal Anodes

This study addresses the critical challenges of lithium dendrite formation in lithium metal anodes by developing a hybrid electrode of single-walled carbon nanotubes (SWCNTs) with MgF₂-coated vapor-grown carbon fibers (MgF₂@VGCF). SWCNTs were initially subjected to acid oxidation to enhance their lithiophilicity by increasing the content of oxygen-containing functional groups. To mitigate the limited Li deposition space of the acid-oxidized SWCNT (AOCNT) electrode, VGCFs were incorporated to increase the porosity and reduce the ionic resistance. Further, MgF₂@VGCF were introduced instead of VGCFs to improve the lithiophilicity of electrode interior, with 20 wt % MgF₂ demonstrating uniform distribution on VGCFs and optimal electrochemical performance. The synergistic design that combines AOCNT’s lithiophilicity, VGCF’s framework, and MgF₂-enabled high lithiophilicity yields a MgF₂@VGCF/AOCNT electrode with enhanced Li metal plating/stripping Coulombic efficiency and cycling stability. This work provides a comprehensive strategy to concurrently engineer lithiophilic sites and CNT-based 3D host structures for advanced lithium metal anodes.