In this paper, a 3D (three-dimensional) layer structure of a pouch-type cell is modeled to understand the distribution of temperature and current density across the pouch type Lithium-Ion Battery (LIB). The electrochemical-thermal characteristics are studied, using 1D (one-dimensional) multiphysics model, and simulation results are validated with experimental results. Three-dimensional (3D) modeling of the battery gives the most efficient estimation of energy density, temperature response, overall heat generation and distribution inside the battery. One such 3D electro-thermal model was developed in this work, and the results obtained by the 3D model were validated by using experimental results obtained from LIBs. Temperature profiles of LIB obtained from 3D modeling indicated that the most heat is accumulated around the positive tab of the battery due to non-uniform current distribution and local internal resistance. The presented model can be used as a fast, yet accurate tool, to optimize the cell design for a particular application and for developing battery thermal management systems.