Efficient synergism of chemisorption and Wackenroder reaction via heterostructured La${}_2$O${}_3$-Ti${}_3$C${}_2$T${}_x$ -embedded carbon nanofiber for high-energy lithium-sulfur pouch cells

Lithium-sulfur (Li-S) batteries have been regarded as promising next-generation energy storage systems due to their high energy density and low cost, but their practical application is hindered by inferior long-cycle stability caused by the severe shuttle effect of lithium polysulfides (LiPSs) and sluggish reaction kinetics. This study reports a La${}_2$O${}_3$-MXene heterostructure embedded in carbon nanofiber (CNF) (denoted as La${}_2$O${}_3$-MXene@CNF) as a sulfur (S) host to address the above issues. The unique features of this heterostructure endow the sulfur host with synergistic catalysis during the charging and discharging processes. The strong adsorption ability provided by the La${}_2$O${}_3$ domain can capture sufficient LiPSs for the subsequent catalytic conversion, and the insoluble thiosulfate intermediate produced by hydroxyl terminal groups on the surface of MXene greatly promotes the rapid conversion of LiPSs to Li${}_2$S via a "Wackenroder reaction." Therefore, the S cathode with La${}_2$O${}_3$-MXene@CNF (La${}_2$O${}_3$-MXene@CNF/S) exhibits excellent cycling stability with a low capacity fading rate of 0.031% over 1000 cycles and a high capacity of 857.9 mAh g${}^{-1}$ under extremely high sulfur loadings. Furthermore, a 5 Ah-level pouch cell is successfully assembled for stable cycling, which delivers a high specific energy of 341.6 Wh kg${}^{-1}$ with a low electrolyte/sulfur ratio (E/S ratio). (© 2023 Wiley‐VCH GmbH)