This paper reports a modeling methodology on the temperature dependence of the discharge behavior of a lithium-ion battery (LIB) in low environmental temperature. The discharge curves from the modeling for the discharge rates ranging from 0.5 C to 5 C under the low environmental temperatures of −20, −10 and 0 °C are compared with the experimental data in order to validate the two-dimensional modeling of the potential and current density distributions on the electrodes of an LIB cell as a function of the discharge time during constant-current discharge. The heat generation rates as a result of electrochemical reactions and ohmic heating are calculated to predict the temperature variations of the LIB as a function of the discharge time. The temperature variations obtained from the modeling agree well with the experimental measurements.