Mitigating lithium-ion cell thermal runaway via selective trace H2 sensing

Thermal runaway in lithium-ion batteries poses a major safety risk. Prior to thermal runaway, cells vent their internal gases as the internal pressure rises, with hydrogen detectable at trace levels of tens to hundreds parts per million. Here, we report that selective trace hydrogen detection, using chemically sensitive field-effect transistors, provides reliable early warning of imminent thermal runaway across multiple cell types and abuse conditions. Systematic abuse tests on commercial cylindrical nickel-cobalt-aluminum (NCA) cathode, pouch nickel-magnanese-cobalt (NMC) cathode, and prismatic lithium-iron-phosphate (LFP) cathode cells at 10%–100% state of charge show that hydrogen is consistently detected in vented gases before thermal runaway. Trace hydrogen detection proves more reliable than conventional temperature, voltage, and pressure sensors. When cell abuse is stopped upon early hydrogen detection, thermal runaway is successfully prevented in all tested cases. These findings establish that trace hydrogen sensing provides early, actionable intelligence to prevent thermal runaway.