Electrochemical Abuse‐Driven Thermal Runaway in Lithium‐Ion Batteries: Evolution From Beginning‐of‐Life to End‐of‐Life

Abstract Thermal runaway, driven by exothermic redox reactions in lithium‐ion batteries, poses a significant barrier to their widespread adoption. While studies typically attribute thermal runaway to mechanical, electrical, or thermal abuse, the impact of electrochemical abuse remains underexplored, despite its relevance in cells degraded through prolonged use. Electrochemical abuse induces complex phenomena within the cell, such as lithium plating, electrolyte consumption, and the reduction of active lithium content (commonly observed as SoC shift), making it challenging to systematically understand how each factor affects thermal runaway. This study elucidates the differences in thermal runaway mechanisms between beginning‐of‐life (BoL) and end‐of‐life (EoL) cells using synchrotron‐based high‐temperature X‐ray diffraction, differential scanning calorimetry, and simultaneous thermal ana…