Engineering Low-Tortuosity Flake-Like Graphitic Carbon via Molten-Salt-Mediated Magnesiothermic Reduction for Lithium Metal Anodes

Graphite offers attractive properties for lithium-metal hosting, including high electrical conductivity, chemical stability, and mechanical robustness, but its dense structure, low porosity, and basal-plane lithiophobicity hinder uniform Li plating. These limitations cause high nucleation barriers and uneven ion transport, rendering conventional graphite ineffective as a practical Li-metal host. Here, we introduce a molten NaCl─assisted low-temperature (650-950 °C) magnesiothermic reduction strategy that reconstructs polymer spheres into flake-like porous multilayered graphene (FMG) with highly aligned graphitic layers, hierarchical meso-macroporosity, and low tortuosity (∼3). The molten salt acts as both a thermal reservoir and structure-directing medium, moderating the exothermic Mg-oxygen reaction, suppressing Mg volatilization, and enabling facet-selective graphitic reorganization inaccessible through conventional reduction routes. As a Li host, FMG achieves uniform Li nucleation with an ultralow overpotential (20 mV), long-term symmetric cycling over 3000 h, and high Coulombic efficiency (98.2% over 400 cycles). LFP||FMG@Li full cells further demonstrate stable capacity retention, underscoring how molten-salt-driven structural engineering transforms graphite from an intrinsically incompatible material into an architecturally optimized host for high-energy lithium-metal batteries.