Lithium-ion batteries are increasingly used in modern society, enabling the widespread adoption of portable electronics, electric vehicles, and renewable energy storage systems. Their high energy density and long cycle life have made them the dominant energy storage technology across multiple sectors. However, safety remains a critical challenge, particularly under abusive operating conditions that may lead to thermal runaway, a rapid and self-accelerating increase in temperature that can result in fire or explosion. Understanding the mechanisms governing thermal runaway is essential for improving battery reliability and developing effective mitigation strategies. In this work, a numerical model of a lithium-ion cell is developed to investigate the conditions leading to thermal instability after mechanical abuse and to analyze the dynamic interaction between electrochemical processes and heat generation.