Synergistic regulation of Li deposition on F-doped hollow carbon spheres toward dendrite-free lithium metal anodes

Abstract

The notorious issues of lithium (Li) dendrite growth and volume change hinder the practical applications of Li metal anodes. LiF as a key component of the solid electrolyte interface (SEI) governs Li⁺ transport and deposition, yet the formation of LiF consumes the anions (PF₆⁻/TFSI⁻) in the electrolyte, preventing the stable cycling of Li anodes. Herein, fluorine (F)-doped hollow carbon (FHC) was synthesized and used to construct a composite current collector with FHC as an F-rich buffer layer for modifying the Cu foil. The F content provided by FHC not only mitigates the anion (PF₆⁻/TFSI⁻) consumption but also enhances the stability of SEI. The hollow structure of FHC with abundant internal space can accommodate deposited Li to relieve the volume change during cycling. Besides, the significantly improved specific surface area of the electrode effectively reduces the local current density to achieve a homogeneous Li deposition. Due to the above cooperation, the symmetrical cell of Cu@FHC-Li||Cu@FHC-Li maintains stable cycling for more than 1800 h with a hysteresis voltage of 19 mV. In addition, full cell coupling with LiFePO₄ cathode delivers excellent long-term cycling and rate performance. This work provides an effective route for developing stable Li metal anodes.