Vacancy-Engineered Ceria Enables 4f-Orbital-Driven Redox Catalysis for Bidirectional Sulfur Conversion in Li─S Batteries.
basic_science · Level V
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- Record sourced from PubMed, PMID 41189401.
- Also identified by DOI 10.1002/adma.202514402.
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Abstract
Redox-flexible rare-earth catalysts featuring partially filled 4f orbitals enable orbital-level modulation of sulfur electrochemistry. Here, an oxygen-vacancy-engineered CeO<sub>2</sub>/carbon nanotube (O<sub>v</sub>-CeO<sub>2</sub>/CNT) composite is reported, configured as a conformal catalytic layer on a commercial separator, to regulate polysulfide redox reactions in lithium-sulfur (Li─S) batteries. In situ and ex situ characterizations, corroborated by DFT calculations, reveal that oxygen vacancies dynamically modulate the Ce electronic environment, enabling reversible Ce<sup>3+</sup>(4f<sup>1</sup>)/Ce<sup>4+</sup>(4f<sup>0</sup>) redox cycling and interfacial charge transfer. This vacancy-induced orbital hybridization between Ce-4f/S-3p and Li-2s/O-2p states enhances LiPS adsorption, lowers the barriers for Li<sub>2</sub>S nucleation and decomposition, and facilitates ion transport, thereby accelerating bidirectional sulfur conversion and ensuring stable redox reversibility. As a result, the designed cell achieves long-term durability (743.2 mAh g<sup>-1</sup> after 1000 cycles at 0.5C), high-rate capability (up to 5C), and high energy density in pouch cells. This work establishes 4f-orbital-mediated defect engineering as a scalable and effective strategy for designing redox-regulating catalysts in high-performance Li─S batteries.