Batteries for use in vehicle applications have complex and coupled electrochemical and thermal phenomena, although these classes of phenomena are often treated separately in modeling efforts. Because important aspects of battery performance, aging, and safety are sensitive to both temperature and electrochemical states, it is important to include both aspects in a single model. We do this by coupling a well-established ID electrochemical model, Dualfoil, with a 3D thermal model of a battery cell, and solving the resultant energy balance with the finite-volume package Fluent. Independent sizing of the electrochemical and thermal meshes enables simultaneously efficient solution of the electrochemical behavior and accurate resolution of heat transfer in a macroscopic cell. Experiments on 18650 cells with embedded thermistors provided a rough validation of the model. We found that convective cooling with a fan resulted in significantly diminished discharge capacity and efficiency at 4A and 8A for a 2.2-Ah energy-type cell. This multiphysics approach represents an important contribution to rigorous treatment of battery systems and should find applications in the design of safe and durable automotive cells and packs. (C) 2013 The Electrochemical Society. All rights reserved.