Physical Sciences Inc. (PSI) proposes to develop a hybrid composite structure of molybdenum disulfide (MoS2) with a class of polysulfide for lithium-sulfur rechargeable batteries on a Phase I program. This cathode provides safety, improved cycle-life, and high capacity at a competitive cost. Crystalline MoS2 is low cost and has a theoretical capacity of 335 mAh/g but it has a low conductivity. The nanocomposite design provides a synergistic improvement in conductivity and electrochemical cycling as a result of the layered MoS2 structure, provided by the intercalation of polysulfide. In the Phase I program, PSI will demonstrate a technology readiness level of 3 with a cathode energy density of greater than 350 mAh/g (800 Wh/kg) using 2 mAh cells. These performance goals will result in an overall battery energy density of 350 Wh/kg. In the Phase II program, PSI will increase cell size to 250 mAh and optimize cell design to further improve cycle life.