Amorphization and defect engineering of Nb2O5 within a graphitic nanocage array for catalytic polysulfide conversion in lithium–sulfur batteries

Abstract

Lithium–sulfur batteries (LSBs) are limited by lithium polysulfide (LiPS) shuttling and sluggish redox kinetics. To address this challenge, we design an amorphous, oxygen-deficient Nb₂O₅ embedded in a mesoporous graphitic framework (Nb₂O₅@MGF) as a multifunctional interlayer that strongly traps and catalytically converts LiPS. The Nb₂O₅@MGF uniformizes the sulfur distribution, exposes vast active interfaces, and offers a reduced ion/electron transportation pathway for expedited redox reaction. Moreover, the amorphous Nb₂O₅ manipulates LiPS chemical affinity, while oxygen vacancies improve catalytic activity. Consequently, the Nb₂O₅@MGF-equipped cell exhibits high capacity and stable cycling. This work presents a synergistic crystallinity and defect-engineering strategy for practical LSBs.