Fe3O4@Fe Core-Shell Okara-Derived Activated Carbon for Superior Polysulfide Control in Lithium-Sulfur Batteries

KC Li and F Shi and XM Chen and ZY Di and MY Hu and LB Sin and CH Wong and LYF Lam and XJ Hu, JOURNAL OF PHYSICAL CHEMISTRY C, 129, 15507-15517 (2025).

DOI: 10.1021/acs.jpcc.5c02606

Lithium-sulfur (Li-S) batteries offer high energy density but suffer from a polysulfide shuttle effect, leading to capacity fading and poor cycling stability. To address this, the Fe3O4@Fe core-shell Okara- derived activated carbon (Fe3O4@Fe-AC) using a sustainable and scalable approach with okara, a soybean residue, as the carbon precursor was developed. Electrochemical tests demonstrate that Fe3O4@Fe-AC/S cathodes exhibit superior cyclic stability, achieving an initial discharge capacity of 755 mAh/g at 0.5C and retaining 572 mAh/g after 500 cycles, with an ultralow capacity decay rate of 0.050% per cycle. At a high rate of 3C, the battery delivers an initial capacity of 557 mAh/g and retains a capacity of 367 mAh/g after 500 cycles, highlighting its excellent rate performance and low polarization potential. This composite enhances battery performance by integrating high-surface-area activated carbon for physical polysulfide adsorption, Fe3O4 for dipole-dipole interactions, and metallic Fe for catalytic LiPS conversion. With its high electrochemical performance, cost-effective synthesis, and sustainable precursor, Fe3O4@Fe-AC represents a promising material for practical Li-S battery applications.

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