Ru‐Ag Dual Atom Sites for Methane Detection Enabling Intelligent Thermal Runaway Warning in Lithium‐Ion Batteries

ABSTRACT Early detection of thermal runaway (TR) is essential for lithium‐ion battery (LIB) safety, as unchecked TR risks catastrophic failures in energy storage systems. Gas‐based sensing offers a faster and more direct approach by detecting decomposition products at the molecular level. CH 4 , a key early‐emission gas, holds particular promise but remains difficult to detect at room temperature due to its chemical inertness. Here, we report a CH 4 sensor based on atomically co‐doped Ru and Ag on MoS 2 , where adjacent single‐atom sites synergistically enhance CH 4 adsorption and activation. The co‐doped sensor exhibits up to 5‐fold higher sensitivity than pristine MoS 2 , enabling reliable ppm level detection at ambient conditions. Integrated into a battery module, the sensor delivers an early thermal runaway warning 90 s ahead of temperature and voltage signals. Combined with control elements such as fans and alarms, this platform enables real‐time safety management, significantly improving the reliability of LIBs in electric vehicles and grid storage.