Experimental study and model validation of Li-Ion battery nail penetration test

Lithium Ion Battery (LIB) are widely used in our everyday life due to their higher operating voltage, specific energy (in terms of weight and volume) and longer life with respect to other battery types. However, safety concerns have arisen and, as their usage is still expected to grow in the next years, research has focused on finding strategies to improve their safety. Thermal Runaway (TR) is the worst event that can happen to a battery as consequence of mechanical, electrical or thermal abuse. TR consists of a chain of exothermic chemical reactions that increase the battery temperature and can lead to fire ignition and explosion of the battery itself. Herein, the state-of-the-art battery structure and materials are presented, along with recent advances related to the prevention and limitation of TR . To better understand the battery response to abuse, different tests can be carried out. This thesis focuses on the nail penetration test, both experimentally and through modelling. Nail penetration tests have been performed on two different 18650 cylindrical batteries using the Accelerating Rate Calorimeter (ARC) provided with the Nail Penetration and Crush Option (NPCO). As the experiments can be costly and time consuming, a model will be developed to predict the thermal behaviour of a LIB after nail penetration test. The experiments are then used to validate the model. Overall, the aim of this thesis is to contribute to the ongoing effort to improve the safety of LIB and ensure their growth and adoption in various application.