Abstract: Employing inexpensive, readily available deoiled asphalt as feedstock, a liquid-phase crosslinking synergised with solid-phase oxidation method was developed based on a process decoupling strategy to produce asphalt-based hard carbon sodium storage materials. The liquid-phase crosslinking reaction increased the size of the raw material's macromolecules and reduced the planarity of the carbon layers. Subsequently, the solid-phase oxidation reaction introduced cross-linked structures containing oxygen-containing functional groups, transforming the material from thermoplastic to thermosetting. This ensured the maximum preservation of the disordered arrangement of the stacked carbon layers during the subsequent carbonization process. Furthermore, the removal of non-carbon elements during the high-temperature stage facilitated the formation of sodium storage sites, such as defects within the carbon layers and ultramicropore structures. Electrochemical testing reveals that HC-340℃-9h-300℃-1300 ℃ hard carbon material prepared under optimal conditions achieves a reversible capacity of 278.45 mA.h/g at d current density of 0.1 A/g with an initial coulombic efficiency of 69.03%, where the ramp region accounts for 58.54% of the total capacity.

Key words: deoiled asphalt, liquid-phase crosslinking, solid-phase oxidation, carbonization, microcrystalline structure, hard carbon, electrochemical properties