• • The optimized HC-10 sample achieves a reversible capacity of 450 mAh/g after 800 cycles at 1 A/g, demonstrating excellent long-term cycling stability for sodium-ion battery anodes.
• • The dual-stabilization strategy (micropore confinement + C–S covalent bonding) suppresses sulfur migration and interfacial side reactions, which is critical for maintaining capacity retention over extended cycling.
• • The introduction of stabilized sulfur species creates additional redox-active sites, enhancing the overall sodium storage capacity beyond that of pristine hard carbon.
• • The two-step thermal process (pre-carbonization at 500 °C, sulfur loading at 600 °C) enables precise control over the sulfur distribution and bonding, offering a scalable route for coal-derived carbon anodes.