Structural engineering of coal-tar-pitch-derived carbon through the addition of perfluoropolyether for enhanced sodium-ion storage

초록

Carbonization of coal tar pitch (CTP) typically produces dense and poorly accessible carbon frameworks, limiting sodium-ion storage performance. In this study, we introduced a thermal-decomposition-assisted strategy using perfluoropolyether (PFPE) as a transient regulator to control the carbonization pathway. During decomposition, PFPE generates fluorine-containing volatile species that transiently influence the evolving carbon framework, perturbing aromatic rearrangement, volatile release, and microcrystal growth, and enabling systematic tuning of the carbon microstructure. At the optimal PFPE content, enhanced stacking coherence was found to coexist with modified gas-accessibility characteristics and multiscale pore-related structural organization, whereas excessive PFPE caused structural over-disruption and reduced the effective utilization of low-voltage storage environments. The improved capacity (similar to 327.5 mAh g(-1)) and enhanced low-voltage capacity contribution (0-0.1 V) are associated with PFPE-induced changes in gas-accessibility characteristics and confined pore-related environments, rather than being solely explained by interlayer expansion. The optimized structure also exhibited enhanced rate capability and cycling stability. This study demonstrates that PFPE-derived transient volatile-mediated modulation during PFPE-assisted carbonization provides an effective and scalable strategy for tailoring gas-accessibility characteristics and multiscale carbon microstructure, offering a simplified and more controllable alternative to conventional pre-oxidation processes for the design of pitch-derived carbon anodes for sodium-ion batteries.

키워드