Electric-Field-Driven Bilayer Interphase from Oxygenated Nanodiamond-Carbon Nanoparticles for Dendrite-Free Lithium Metal Batteries

초록

Lithium metal batteries (LMBs) offer exceptional energy density but are severely limited by dendrite formation and unstable interphases. Here, this work presents an electric field-driven in situ strategy to construct a vertically graded interphase using an oxygen-rich nanodiamond/carbon (O-ND/C) composite. During Li plating, conductive carbon migrates toward the current collector, forming a C-enriched conductive sublayer beneath a lithiophilic O-ND-rich insulating layer. This bilayer architecture homogenizes Li-ion flux, lowers the nucleation barrier, and simultaneously ensures mechanical robustness and electronic insulation, thereby enabling dendrite-free Li deposition. The optimized O-ND with 10 wt% of C interphase demonstrates outstanding electrochemical stability, maintaining an ultralow overpotential of 9.5 mV for 5800 h in symmetric cells and an average Coulombic efficiency (CE) of 98.8% to 700 cycles. In full-cell configurations with LiFePO4 cathodes, stable operation is sustained for up to 1500 cycles, areal capacity of 12.1 mAh cm-2 retained 9.9 mAh cm-2 after 50 cycles even under industrially relevant high cathode loading (93.8 mgLFP cm-2). Complementary density functional theory calculations confirm that O-ND surfaces enhance Li adsorption and diffusion, corroborating the experimental results. This work provides mechanistic insight into field-driven interphase engineering and offers a practical pathway toward safe, high-energy density LMBs.

키워드