Extraction and Reconstruction of Carbon Components from Coal Gasification Fine Slag for Li-O2 Battery Cathode Catalysts

The ever-increasing output of coal gasification slag from coal gasification technology has created an urgent need for its efficient disposal. In this study, the fine-slag fraction is uti-lized as a precursor to prepare a carbon electrocatalyst for Li-O2 batteries. Residual carbon was extracted from coal gasification fine slag via an integrated alkali-acid co-activation process. Subsequently, hydrothermal modification reconstructed the carbon microstructure and strengthened its coupling with intrinsic Ca-containing species. The as-prepared slag-derived catalyst improved oxygen-reaction kinetics at the battery cathode and effectively reduced polarization. The Li-O2 cells delivered a low charge–discharge voltage gap of 1.02 V, a high discharge specific capacity of 9480 mAh g−1, and stable long-term cycling for more than 870 h. The enhanced electrochemical performance arises from the synergistic interplay among the reconstructed carbon framework, surface defects, oxygen-containing functional groups, and Ca-containing species, with the latter serving as a major source of active sites for the oxygen electrocatalytic reactions. This work establishes a resource-utilization pathway from coal gasification slag to high-end energy-storage applications, aligning with green development goals to address both mining-area energy demands and solid-waste pollution.