Electrochemically‐Triggered Spin Switching Enables Anti‐Passivation of Active Sites in Lithium–Sulfur Catalytic Chemistry

Abstract

ABSTRACT The irreversible accumulation of insulating Li 2 S in lithium–sulfur batteries (LSBs) constitutes a central bottleneck that triggers active‐site passivation and performance degradation of catalytic materials. To address the long‐standing challenge faced by conventional steady‐state catalysts in simultaneously balancing sulfur conversion kinetics and long‐term stability, we propose a spin‐state‐programmable dynamic catalysis strategy. Herein, Zero‐strain Wadsley–Roth phase TiNb 2 O 7 is employed as a model system. Through a customized catalytic stability evaluation protocol combined with in situ characterization and multiscale kinetic analysis, a π–electron feedback mechanism induced by a reversible Ti 4+ /Ti 3+ transition within the operating voltage window of LSBs is revealed. This mechanism directionally regulates the occupation of Li–S antibonding states of Li 2 S, thereby promoting reversible Li 2 S dissociation and suppressing interfacial passivation. Enabled by this mechanism, the LSBs maintains 94.6% capacity retention over 240 cycles even at an extreme temperature of −33°C. Furthermore, an energy density of 560 Wh kg −1 is achieved in pouch cells, which operate stably for 100 cycles. Our study establishes a new materials design principle and mechanistic foundation for simultaneously enhancing activity and stability in sulfur conversion catalytic chemistry.