This book provides a concise overview of the use of ionic liquids as electrolytes in lithium-ion batteries (LIBs) from a theoretical and computational perspective. It focuses on computational studies to understand the behavior of lithium ions in different ionic liquids and to optimize the performance of ionic liquid-based electrolytes. The main features of the book are as follows: • Provides a thorough understanding of the theoretical and computational aspects of using ionic liquids as electrolytes in LIBs, including the evaluation and reproducibility of the theoretical paths. • Covers various computational methods such as density functional theory, molecular dynamics, and quantum mechanics that have been used to study the behavior of lithium ions in different solvents and to optimize the performance of ionic liquid-based electrolytes. • Discusses recent advances such as new computational methods for predicting the properties of ionic liquid-based electrolytes, new strategies for improving the stability and conductivity of these electrolytes, and new approaches for understanding the kinetics and thermodynamics of redox reactions with ionic liquids. • Suggests how theoretical insights can be translated into practical applications for improving performance and safety. This monograph will be of interest to engineers working on LIB optimization.