Lithium-sulfur (Li-S) battery is widely recognized as the most promising battery technology for future electric vehicles (EV). To understand the environmental sustainability performance of Li-S battery on future EVs, here a novel life cycle assessment (LCA) model is developed for comprehensive environmental impact assessment of a Li-S battery pack using a graphene sulfur composite cathode and a lithium metal anode protected by a lithium-ion conductive layer, for actual EV applications. The Li-S battery pack is configured with a 61.3 kWh capacity to power a mid-size EV for 320 km range. The life cycle inventory model is developed with a hybrid approach, based on our lab-scale synthesis of the graphene sulfur composite, our lab fabrication of Li-S battery cell, and our industrial partner's battery production processes. The impacts of the Li-S battery are assessed using the ReCiPe method and benchmarked with those of a conventional Nickle-Cobalt-Manganese (NCM)-Graphite battery pack under the same driving distance per charge. The environmental impact assessment results illustrate that Li-S battery is more environmentally friendly than conventional NCM-Graphite battery, with 9%–90% lower impact. Finally, the improvement pathways for the Li-S battery to meet the USABC (U.S. Advanced Battery Consortium) targets are presented with the corresponding environmental impact changes.