Manipulating fast Li₂S redox via carbon confinement and oxygen defect engineering of In₂O₃ for lithium–sulfur batteries

Lithium–sulfur (Li–S) batteries have been considered as promising energy storage systems due to the merits of high energy density and low cost. However, the lithium polysulfides (LiPSs) diffusion and sluggish redox kinetics hamper the battery performance. In this work, low-bandgap indium oxide (In₂O₃) with dense oxygen vacancies (In₂O_3−x, 0 < x < 3) confined in nitrogen-doped carbon column (NC) is developed as a desirable LiPSs immobilizer and promoter to address these intractable problems. The NC confined In₂O_3−x with rich O vacancies (In₂O_3−x@NC) lowers the bandgap of 1.78 eV, strengthens the chemical adsorbability to LiPSs, and catalyzes the bidirectional Li₂S redox. Attributed to the structural and chemical cooperativities, the obtained sulfur electrodes exhibit a stable cycling over 550 cycles at 1.0 C and splendid rate capability up to 4.0 C. More significantly, when the sulfur-loading reaches as high as 5.5 mg·cm⁻², the cathodes achieve an areal capacity of 5.12 mAh·cm⁻² at 0.1 C. The strategy of NC confined catalyst with rich defects engineering demonstrates great promise in the development of practical Li–S batteries.