A sensitivity analysis of a mathematical model of a lithium-sulfur (Li–S) battery was performed, focusing on the effects of the discharge current and the electronic conductivity of the cathode by investigating the response of the model to variations of these parameters over a wide range of values. The behavior of the model battery system with respect to the variations of each parameter is explained in detail. The nonlinear response of the model to the parameter variations is presented. In particular, the discharge current causes different patterns of the voltage plateaus. The importance of the electronic conductivity of the cathode is also discussed in detail. A minimum conductivity requirement to activate the cell was observed, beyond which no significant improvement of the capacity performance occurs. This report evaluates the electrochemical aspects of different experimental results particularly regarding discharge voltage plateaus, and moreover, demonstrates the limits of the model.