Integrating an In‐Plane Electron‐Conductive Separator to Enable Short‐Circuit Warning in Lithium–Sulfur Batteries

Abstract Lithium–sulfur (Li–S) batteries are one of the most competitive candidates for high‐energy‐density batteries. However, the high energy density and high reactivity of the lithium anode and sulfur cathode make the safety issues of Li–S batteries particularly prominent. Herein, an early warning strategy for the short circuits in Li–S batteries is explored by integrating an in‐plane electron‐conductive separator. The internal short circuits caused by lithium dendrites or manufacturing defects can be quickly and accurately predicted before catastrophic thermal runaway, with enough time to take rescue measures. The separator with high thermal conductivity also facilitates the heat dissipation of the cell, thus reducing the risk of thermal runaway under abuse. The fast and reliable early warning strategy based on the in‐plane electron‐conductive separator builds the Great Wall of active defense against inherently unsafe Li–S batteries.