An in situ LiF-enriched solid electrolyte interphase from CoF2-decorated N-doped carbon for dendrite-free Li metal anodes

Abstract

Lithium (Li) metal has shown great potential as the anode for high-energy-density rechargeable batteries due to its ultrahigh theoretical specific capacity and low redox potential. However, the practical application of the Li metal anode is inherently limited by the uncontrollable Li dendrite growth and unstable solid electrolyte interphase (SEI) layer. Herein, a CoF₂-decorated N-doped carbon (denoted as CoF₂@NC) is synthesized by a convenient fluoridation treatment after the carbonization of ZIF-67 precursor and used as a functional coating on the bare Cu current collector for enabling uniform Li deposition. Due to the lithiophilic properties of the CoF₂@NC matrix and the as-generated LiF-enriched SEI layer, the CoF₂@NC-modified current collector demonstrates decreased nucleation potential and a more stable Li stripping/plating process. As a result, the symmetric cell with a Li@CoF₂@NC/Cu electrode exhibits substantially enhanced cycling stability for 1200 h under the conditions of 1 mA cm⁻² and 1 mA h cm⁻². Moreover, the assembled LiFePO₄ full cell with a Li@CoF₂@NC/Cu anode delivers excellent rate performance and cycling stability, endowing high initial discharge capacity (149.3 mA h g⁻¹) and capacity retention (95.45%) after 500 cycles at 1C. This work emphasizes that the synergistic effect of the lithiophilic substrate and robust SEI layer is essential for high-performance Li metal batteries.