Efficient Synergism of Chemisorption and Wackenroder Reaction via Heterostructured La_2O_3-Ti_3C_2T_x -Embedded Carbon Nanofiber for High-Energy Lithium-Sulfur Pouch Cells

摘要

Lithium-sulfur (Li-S) batteries have been regarded as promisingnext-generation energy storage systems due to their high energy density andlow cost, but their practical application is hindered by inferior long-cyclestability caused by the severe shuttle effect of lithium polysulfides (LiPSs) andsluggish reaction kinetics. This study reports a La_2O_3-MXene heterostructureembedded in carbon nanofiber (CNF) (denoted as La_2O_3-MXene@CNF) as asulfur (S) host to address the above issues. The unique features of thisheterostructure endow the sulfur host with synergistic catalysis during thecharging and discharging processes. The strong adsorption ability provided bythe La_2O_3 domain can capture sufficient LiPSs for the subsequent catalyticconversion, and the insoluble thiosulfate intermediate produced by hydroxylterminal groups on the surface of MXene greatly promotes the rapidconversion of LiPSs to Li2S via a “Wackenroder reaction.” Therefore, the Scathode with La_2O_3-MXene@CNF (La_2O_3-MXene@CNF/S) exhibits excellentcycling stability with a low capacity fading rate of 0.031 over 1000 cycles anda high capacity of 857.9 mAh g~(?1) under extremely high sulfur loadings.Furthermore, a 5 Ah-level pouch cell is successfully assembled for stablecycling, which delivers a high specific energy of 341.6 Wh kg~(?1) with a lowelectrolyte/sulfur ratio (E/S ratio).