Ionic-Liquid-Triggered Amorphization Engineers Symmetry-Breaking p-Block Bismuth Oxides with Electric Dipole Domains for Practical Lithium-Sulfur Batteries.

Abstract

The practical application of lithium-sulfur batteries is severely hindered by the sluggish sulfur redox kinetics and the notorious lithium polysulfides (LiPSs) shuttle effect. Herein, we report a strategy utilizing an Fe-based ionic liquid to trigger amorphization, engineering symmetry-breaking p-block bismuth oxides on carbon nanofibers (CNFs) with electric dipole domains and asymmetric Fe₁-O-Bi electronic bridges (Fe₁⊂A/C-Bi₂O₃@CNFs). The amorphous phase induces significant electronic delocalization, facilitating substantial orbital overlap and creating electron transport channels for rapid redox of LiPSs. Specifically, the asymmetric Fe₁-O-Bi electron bridges lower the p-band center through 3d-2p-6p multi-orbital coupling, optimizing the chemical adsorption of LiPSs and preventing active site poisoning. The electronic dipole domain functions as an electron/Li⁺ "pump" to enhance charge transfer and Li⁺ diffusion. In addition, the electric dipole domain induces dipole-dipole interactions, facilitating Li─S bond polarization and cleavage. As a result, the Fe₁⊂A/C-Bi₂O₃-based cell achieved a cyclability of 698 mAh g^-1 at 1.0 C over 1000 cycles with a degradation rate of 0.026% per cycle, and a high areal capacity of 6.8 mAh cm^-2 under a sulfur loading of 7.4 mg cm^-2. The strategy of constructing an electronic dipole domain through amorphization provides a new direction for the rational design of efficient catalysts for sulfur redox reactions.