Synergistic Regulation of Intrinsic Lithiophilicity and Mass Transport Kinetics of Non-Lithium-Alloying Nucleation Sites for Stable Operation of Low N/P Ratio Lithium Metal Batteries

Abstract

Constructing functional materials on a 3D host is an efficient strategy to tackle issues of lithium (Li) metal anodes. Although non-Li-alloying materials provide structural stability during cycling due to reduced lattice distortions, low lithiophilicity and sluggish mass transport kinetics limit their functionality. Herein, a synergistic strategy is proposed to improve intrinsic lithiophilicity and mass transport kinetics of non-Li-alloying nucleation sites and demonstrate its remarkable efficacy. Two carbon fiber (CF) hosts coated by non-Li-alloying nanosheets with and without oxygen-enriched carbon filler (OCF) as lithiophilicity and mass transport booster (OCF-DSC@CF and DSC@CF, respectively) are constructed and their physiochemical properties are systematically evaluated to reveal the efficacy of OCF. By advanced characterization techniques, including 3D tomography and location-dependent electron energy loss spectroscopies, the complex heterostructure of OCF-DSC@CF with distinctive roles of each constituent is clearly identified. As verified by theoretical and electrochemical analyses, the incorporation of OCF endows OCF-DSC@CF with substantially improved lithiophilicity and mass transport kinetics. Moreover, OCF-DSC@CF induces a multifunctional SEI enriched with LiF and LiCx, which exhibits well-balanced electrical resistivity and ionic conductivity. Benefiting from these attributes, OCF-DSC@CF exhibits an unprecedented cyclability under a low N/P ratio of 1.8, achieving 700 cycles at 0.5C with an exceptional capacity retention of 97.8%. The poor intrinsic lithiophilicity and mass transport kinetics of non-Li-alloying nucleation sites are synergistically regulated by the incorporation of OCF. The complex heterostructure of OCF-DSC@CF is scrutinized by advanced characterization techniques, including location-dependent EELS and 3D tomography. Theoretical and experimental investigations verify the efficacy of OCF as a lithiophilicity- and mass transport kinetics booster. image