Synergistic Regulation of Interfacial Charge Redistribution and Charge Transfer via Built‐In Electric Field in Heterojunctions for High‐Performance Lithium–Sulfur Batteries

Li–S batteries possess an ultrahigh theoretical specific capacity of 1675 mAh g −1 , yet their practical application is still hindered by the shuttle effect and sluggish sulfur redox kinetics. Current research on Li–S batteries mainly focuses on interface engineering strategies, while a systematic understanding of how the built‐in electric field (BIEF) induced by work function mismatch regulates interfacial charge redistribution and sulfur‐species conversion remains limited. In this work, we constructed a Co@NC Mott–Schottky heterojunction to induce interfacial charge redistribution. Experimental and theoretical results demonstrate that work function mismatch between the two phases also drives the spontaneous formation of a BIEF, which accelerates the bidirectional redox kinetics of sulfur. This BIEF drives the directional migration of interfacial charges and modulates the energy barriers of sulfur species conversion. Consequently, the Co@NC/S cathode delivers a high capacity retention of 82.1% after 400 cycles at 5 C, and retains 77.2% after 120 cycles under high sulfur loading (5.6 mg cm −2 ) and lean electrolyte conditions (E/S = 4.0 μL mg −1 ). This work reveals the critical role of BIEF in boosting sulfur electrochemistry and provides a transferable interface engineering design strategy for high‐performance Li–S batteries.