Interfacial electron engineering via BaTiO₃@Ti₃C₂ Mott-Schottky heterojunctions for advanced LiS batteries

The notorious polysulfides shuttle effect and intrinsically sluggish sulfur redox kinetics severely hinder the practical commercialization of lithium‑sulfur (LiS) batteries. Herein, BaTiO₃@Ti₃C₂ Mott-Schottky heterojunctions are prepared, synergistically coupling the ferroelectric polarization of BaTiO₃ with the metallic conductivity of Ti₃C₂. Theoretical calculations and experimental analyses reveal that interfacial electron transfer from Ti₃C₂ populates states near the Fermi level of BaTiO₃, substantially optimizing overall electronic conductivity. Furthermore, compared to BaTiO₃ and Ti₃C₂, BaTiO₃@Ti₃C₂ Mott-Schottky heterojunctions demonstrate a lower free energy change (0.74 eV) and Li₂S decomposition energy barrier (1.23 eV), significantly improving the kinetics of sulfur conversion. Consequently, by employing BaTiO₃@Ti₃C₂ functionalized separators, LiS batteries demonstrate outstanding rate performance (764.8 mAh g^-1 at 3C) and cycling stability (an ultralow capacity fading rate of 0.056 % per cycle over 700 cycles). Impressively, a high areal capacity of 4.5 mAh cm^-2 is achieved under a high sulfur loading of 4.98 mg cm^-2.