The major shift in the mobility industry towards electric vehicles requires the development of safer energy storage systems (ESS). Li-ion ESS has been at the forefront of automotive, aerospace, and stationary ESS for power backup applications, albeit it suffers from thermal instability issues, which prompts investigation into the thermal behavior of these systems. Thermal modeling of Li-ion batteries is an essential practice to understand the mechanisms behind heat generation and distribution, and cognizance of the thermal behavior is crucial to developing safer Li-ion batteries and optimal thermal management solutions. However, one of the most significant challenges associated with developing thermal models is parameter identification due to the unique layered construction of a Li-ion cell. The simplest thermal model for a Li-ion battery can require the identification of ten or more unknown parameters. The accuracy of the model depends on the accuracy of the parameter identification process. Thermal models also require electrical models to predict heat generation in the cell, which requires a plethora of unknown parameters to be identified to simulate the electrical behavior of the cell. The overall accuracy of predicted temperature and thermal distribution is dependent on the accuracy of both the electrical and thermal models. The parameter identification for thermal modeling requires extensive experimentation, with its challenges, such as heat propagation to the experimental setup and power cables connecting the cell to the battery cycler. The goal of the research presented in this thesis is to develop an innovative experimental setup, test procedures, and calibration strategy for a lumped-parameter thermal model with the aim of accurately estimating the temperature of the cell and the cell tabs. The research aims at developing a test bench capable of minimizing the heat transfer from the cell to the power cables and the ambient. Two thermal experiments with different boundary conditions are designed that use the test bench for parameter identification and calibration. Finally, the parameters are validated using a standardized duty cycle. An equivalent circuit model is used in the study to estimate the electrical behavior of the cell. The test bench, experiments, and parameter identification, calibration, and validation process developed in the thesis can be used for the thermal characterization of Li-ion cells.