Thermal Model for the analysis of the Thermal Runaway in Lithium-Ion Batteries using Accelerating Rate Calorimetry

Accelerating rate calorimetry (ARC) has emerged as a powerful tool for evaluating the thermal behavior of Li-ion cells and identifying potential safety hazards. In this work, a new physical thermal model has been developed based on the first law of thermodynamics for analyzing heat and mass generated by Lithium-ion battery cells under thermal abuse conditions during EV-ARC tests. The analysis is based on the experimental data gathered from an ARC, including different temperatures and pressure inside a gas-tight canister located in the calorimeter chamber, as well as the gas composition at the end of the test. The energy balance of the battery cell includes: the energy released by the cell, the internal energy of the elements inside the canister, heat transfer between elements inside the canister, as well as the mass transfer between the cell and the gases inside the canister. The model allows obtaining the total energy released during thermal runaway for any kind of cylindric Li-ion cells chemistries, as well as the evolution of the instantaneous gas compositions and the mass released as a result of the thermal runaway. This work provides essential insights into this phenomenon caused by thermal abuse in an extended volume accelerated rate calorimeter, to support safer thermal management system development.