Molecular‐Electrode Co‐Engineering Enables High‐Capacity, Long‐Cycling Sulfur‐Based p‑Type Organic Cathodes

Sulfur‐centered p‐type organic cathode materials, particularly those based on thianthrene, have attracted significant interest for high‐voltage lithium‐ion batteries due to their intrinsically high redox potentials and versatile molecular designability. Nevertheless, their practical application remains hindered by low reversible capacity and poor cycling durability, mainly arising from severe dissolution in organic electrolytes or unsatisfied polymer electrode architecture. Herein, we shift focus from conventional thianthrene to the high‐capacity benzo[b]thiophene unit and rationally design two non‐fused and rigid monomers, 1,4‐di(benzothiophen‐2‐yl)benzene (DBTB) and 2,5‐di(benzothiophen‐2‐yl)pyrazine (DBTP), that synergistically integrate molecular enlargement, enhanced planarity, and improved van der Waals forces to suppress dissolution. Crucially, subsequent in situ electropolymerization during charging within the assembled cell directly forms morphology‐optimized polymer electrode architecture. This integrated strategy overcomes the fundamental capacity‐stability trade‐off that has plagued sulfur‐based cathodes. As a result, DBTP‐based cathode delivers a high capacity of 155.1 mAh g − 1 (99.6% of theoretical capacity) with exceptional cycling stability (82.1% retention after 5000 cycles at 5 C), surpassing all reported thianthrene‐based polymer cathodes (<110 mAh g − 1 , ≤500 cycles) and small molecule cathodes (<100 mAh g − 1 , ≤450 cycles). The molecular‐electrode co‐engineering strategy demonstrated here provides a new pathway to high‐capacity, long‐life sulfur‐based p‐type cathodes.