Exploring Iron-Catalyzed Biphasic Thermal Graphitization via High-Temperature In Situ XRD to Investigate Biographite Structural Evolution for Sustainable Battery Anodes

Iron-catalyzed biographitization is a crucial research area offering solutions to the exponentially growing graphitic carbon demand; however, the complete mechanism of graphitic structure development is still obscure. In an exclusive attempt, in situ high-temperature X-ray diffraction (XRD), ambient temperature XRD, Positron Annihilation Lifetime Spectroscopy (PALS), Raman spectroscopy, and transmission electron microscopy (TEM) were used to record the distinctive and incremental graphitic transformation of biocarbons influenced by a zerovalent iron catalyst as a function of temperature. The study confirmed that the catalytic graphitization of biocarbon is controlled by the thermally regulated phase behavior of the iron catalyst, which employs a newly uncovered phase-coupled mechanistic pathway that involves both homogeneous (solid-solid) interactions and heterogeneous (liquid-solid) catalysis for the development of anode-grade biographite for lithium-ion batteries (LIBs). The solid-state dissolution initiates the graphitic transformation, near-liquefaction temperatures promote carbon network growth, and the molten catalyst assists in stacking and maturity for crystalline graphite formation. Comprehensive transitional insights into the evolutionary phases of iron-catalyzed biographitization provide a practical understanding of the thermo-catalytic factors influencing graphitic reorganization and atomic-scale defects, which are essential for the development of high-quality sustainable anode materials and their future commercialization.