Overcharge-Induced Thermal Runaway of LiNi0.5Co0.2Mn0.3O2 Batteries: An Integrated Electro-Thermal-Gas Model

This study develops a novel electrochemical-thermal-gas coupled model to comprehensively characterize the overcharge-induced thermal runaway (TR) mechanisms in lithium-ion batteries, addressing critical gaps in existing simulation frameworks. The model uniquely integrates three interdependent processes: (1) voltage evolution via dynamic electrode potential tracking, (2) temperature rise incorporating multistage heat sources (Joule heating, exothermic TR reactions, and internal short-circuit effects), and (3) gas generation kinetics modeled through Arrhenius-based reaction rates and gas state equations. Experimental validation confirms precise prediction of electrochemical-thermal-gas behavior during overcharge. Key mechanistic insights reveal that gas pressure (contributing 75% to total swelling force) and vapor pressure from the electrolyte (contributing 22% to total swelling force) collectively drive 97% of battery casing deformation and rupture. Notably, electrolyte oxidation and lithium-deposition-induced electrolyte reactions are the dominant contributors to heat and gas generation during overcharging. Through further modeling analysis, a strategy to improve the overcharge performance of lithium-ion batteries by increasing the electrolyte oxidation potential is proposed. Beyond theoretical contributions, the model establishes a groundbreaking early-warning capability through real-time gas evolution monitoring prior to venting, offering immediate practical value for battery management systems.