In Situ Thermally‐Driven Radial Heterophase Evolution of δ‐Bi 2 O 3 Modulates the p ‐Block Bi 6p Orbitals and p ‐Band Center for Enhancing Sulfur Redox Reactions

The commercialization of lithium-sulfur batteries is hindered by challenges such as the shuttle effect of lithium polysulfides (LiPSs), slow sulfur redox reaction kinetics, and poor electrical conductivity. The electronic configuration of the p-block Bi 6p orbitals is modulated through an in situ thermally-induced reduction strategy using lignin-based carbon nanofibers (CNFs). This approach enables the radial gradient heterophase transformation of δ-Bi₂O₃, leading to the formation of a high-density heterojunction network composite (δ-Bi₂O₃-O_VS/Bi@CNFs) rich in oxygen vacancies (O_VS), which effectively moderates the adsorption of LiPSs and enhances the kinetics of sulfur redox reactions. Based on the δ-Bi₂O₃-O_VS/Bi@CNFs, a high-energy-density (377 Wh kg^-1) pouch cell with a capacity of 1.8 Ah is fabricated and successfully used in drone flights, highlighting its potential for practical applications. This work elucidates the mechanism of in situ thermally-induced radial-gradient heterophase evolution of p-block metal oxides and the influence of 6p-orbital electron modulation on the sulfur redox reaction.