Root and suppression of shuttling gain a uniform Li2O interphase toward 610 Wh kg−1 lithium–sulfur batteries

Concentration-gradient-driven polysulfide (LiPS) shuttling has long limited lithium–sulfur batteries, whereas the electromigration shuttling pathway induced by ionized LiPS has remained undetected. By combining mass conservation with Faraday’s law, we derive a LiPS conservation equation that quantitatively decouples concentration-gradient and electromigration shuttling, identifying electromigration as a degradation pathway that is strongly enhanced under high current densities. Accordingly, we propose a lithium-reservoir strategy using Ti3C2Tx materials selected through screening to accelerate Li⁺ transport, effectively suppressing electromigration shuttling. Cryo-electron microscopy reveals that the surface chemistry of Ti3C2Tx drives a superoxide radical-mediated formation of a dense and uniform Li2O solid-electrolyte-interphase (SEI), which serves as a robust barrier against residual shuttling. The assembled 9 Ah pouch cells exhibit benchmark energy densities of 611.5 Wh kgtotal⁻1 for 150 cycles. Our study systematically elucidates the root of polysulfide shuttling and introduces a radical-enabled strategy to construct a uniform Li2O SEI, representing a significant advance for battery research.