Unlocking Latent Titanium Active Centers Through the Synergistic Effect of Oxygen Vacancies and Boron Doping for Accelerated Sulfur Redox Reactions in Silicon‐Sulfur Batteries

Abstract

ABSTRACT The introduction of multiple defects into a single electrocatalyst enables precise modulation of active centers electronic states, thereby accelerating sulfur reduction kinetics in lithium‐sulfur batteries. However, the individual roles and cooperative interactions of such defects remain elusive. Herein, we engineered a dual‐defect TiO 2 incorporating boron doping and oxygen vacancies to synergistically activate Ti centers. Calculations reveal that the coexistence of both defects under heterojunction structure markedly enhances the Ti 3d occupied electronic states below the Fermi level, which is absent in pristine and single‐defect counterparts. Such a shift corresponds to the transition from the initial 3d 0 (Ti 4+ ) to the 3d 1 (Ti 3+ ) configuration, primarily introducing occupied electrons into the t 2g orbitals. This phenomenon reflects a unique synergistic activation of Ti sites, rather than a mere additive effect of individual defects. Therefore, the dual‐defect system synergistically enhances polysulfides anchoring at Ti sites and promotes interfacial charge transfer, enabling superior lithium‐sulfur battery performance (a low decay‐rate of 0.045% over 1000 cycles under excess lithium conditions). Based on the enhanced sulfur reduction kinetics, we further assembled silicon‐sulfur full cells. This novel battery system exhibits exceptional stability and safety, maintaining stable cycling for 1000 cycles under limited lithium supply (1.5 NP ratio, 3.5 mg s cm −2 ).