Boosting Bidirectional Polysulfides Conversion in Li–S Batteries by Ion Transport Management via Built‐In Electric Field

Accelerating sulfur redox reaction (SRR) kinetics is important for suppressing the shuttle effect in Li–S batteries. While most efforts focus on optimizing lithium polysulfides (LiPSs) adsorption and conversion, the critical role of directional migration of Li + and polysulfide anions (S n 2− ) remains overlooked. Here, we report a 2D atomic Co‐decorated TiN/TiO 2 in‐plane heterostructure (Co‐TiN/TiO 2 ) that uniquely integrates highly catalytic Co single atoms, stabilized by strong metal–support interaction, with a heterointerface‐induced built‐in electric field (BIEF). Unlike conventional single‐atom catalysts or simple heterostructures, this design works like a “supply‐and‐removal” production line: the BIEF drives Li + toward the active sites for charge compensation while expelling S n 2− away, thereby mitigating the accumulation of LiPSs, which is consistent with the observed prevention of catalyst passivation and enhanced SRR kinetics. Consequently, the battery with Co‐TiN/TiO 2 catalyst delivers a high initial capacity of 1075 mAh g −1 at 1 C and remarkable cycling stability with a decay rate of only 0.05% per cycle over 1000 cycles. Even under high sulfur loading and lean electrolyte conditions, it maintains a high areal capacity of 4.7 mAh cm −2 and outstanding cycling performance. This work highlights the importance of coordinated ion management in designing high‐efficiency catalysts for Li–S batteries.