Present day automotive battery packs typically consist of a large number of LIBs (few hundreds to thousands) to meet the required power and capacity needs of an EV. The high cost and limited mileage of present LIB-powered cars are due to the intrinsic limited capacities of the Li-ion insertion cathodes, which are nearing their practical limits and even a two-fold increase in energy density of current LIB cells is insufficient for the long-term demands of transport and electricity storage. Hence, for a wide deployment of EVs and maximizing electrification of the road transportation system, drastic improvements in today’s battery pack performance is needed. Among new generation of lithium batteries, high theoretical energy density (~600 Wh/Kg) that may be 4-5 times higher compared to that of Li-ion batteries, good low-temperature performance, and abundance of inexpensive nontoxic raw material, make the lithium sulfur batteries (LSB) a promising candidate for major energy applications. However, there are several major issues facing rechargeable LSBs that impede their practical applications. In other words, challenges such as fast capacity loss, limited cycle life, high self-discharge rates, over-heating, and volume change of the cathode have hindered mass commercialization of these cells and limit their current application to UAVs and defense applications where the lightness and high energy is more important than life cycle. Although a wide range of experimental researches have investigated novel strategies, material and designs for the cells, the mathematical and theoretical studies are scarce. Theoretical modeling plays crucial role in the exploration of the phenomena happening in the LiS cells. A mathematical model is presented to provides a better understanding of the complex multistep electrochemical reactions, side reactions, multiscale and multi component transport phenomena, phase change phenomena and precipitation reaction, and porosity and volume change of the cathode.