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초록

The development of cost-effective, high-performance carbon (C) anodes is essential for advancing the commercial application of sodium-ion batteries (SIBs), yet it remains a significant challenge. Petroleum coke (PC), owing to its inherent electrical conductivity and low cost, represents an attractive precursor for electrode materials in energy storage systems. Nevertheless, the narrow interlayer spacing and highly ordered graphitic domains of pristine PC restrict sodium-ion (Na+) accommodation, resulting in limited reversible capacity and low initial coulombic efficiency (ICE). In this work, a precursor transformation strategy was employed to expand the interlayer spacing and generate abundant closed pores within PC-derived carbons, thereby markedly enhancing Na+ storage capability. This was accomplished by introducing oxygen-containing functional groups via mixed-acid oxidation, followed by high-temperature carbonization to decompose these groups and induce microcrystalline rearrangement, leading to the evolution of pore structures from open to closed. As anodes for SIBs, the modified PC carbons deliver a substantially improved reversible capacity, increasing from 243.05 to 353.52 mAh g−1, along with a notable rise in ICE from 70.9% to 87.6%. Furthermore, the electrodes exhibit excellent structural stability, sustaining long-term cycling over 400 cycles at current densities of 0.5 and 1.0 A g−1. Their outstanding rate performance, particularly the high-capacity retention at 1.0 A g−1, underscores the structural merits of the engineered PC-derived carbons. © 2026 Elsevier B.V.

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