Thermal Runaway Mechanism in Ni‐Rich Cathode Full Cells of Lithium‐Ion Batteries: The Role of Multidirectional Crosstalk

Abstract Crosstalk, the exchange of chemical species between battery electrodes, significantly accelerates thermal runaway (TR) of lithium‐ion batteries. To date, the understanding of their main mechanisms has centered on single‐directional crosstalk of oxygen (O 2 ) gas from the cathode to the anode, underestimating the exothermic reactions during TR. However, the role of multidirectional crosstalk in steering additional exothermic reactions is yet to be elucidated due to the difficulties of correlative in situ analyses of full cells. Herein, the way in which such crosstalk triggers self‐amplifying feedback is elucidated that dramatically exacerbates TR within enclosed full cells, by employing synchrotron‐based high‐temperature X‐ray diffraction, mass spectrometry, and calorimetry. These findings reveal that ethylene (C 2 H 4 ) gas generated at the anode promotes O 2 evolution at the ca…