The lithium-sulfur (Li-S) battery system has been widely lauded as a candidate to replace lithium-ion (Li-ion) technology in weight-critical applications such as electric vehicles, aerospace missions, and personal electronics. The attractiveness of this design comes from its high theoretical energy density (>2300 Wh/kg vs. ~400 Wh/kg for Li-ion), as well as the low cost/abundance of sulfur. However, despite decades of research, a commercially-competitive Li-S battery remains elusive. This is largely due to functional challenges such as poor conductivity, electrolyte-soluble reaction intermediates, and anode surface passivation, which reduce the capacity, efficiency and cycle life of practical cells.This talk will broadly cover my graduate research efforts to develop and study free-standing gel electrolytes for the Li-S system, successfully integrate them into working devices, and demonstrate their effect on cell performance. Solvate ionogel (SIG) electrolytes based on Li(G4)TFSI are demonstrated with room-temperature conductivities >10-3 S/cm and lithium transference numbers up to >0.5. The transport and charge-transfer properties of these electrolytes are found to depend heavily on polymer-ion interactions that are specific to this class of materials. SIG electrolytes are then integrated into separators and cathodes for Li-S batteries using an in-situ crosslinking method, and the resulting quasi-solid-state cells demonstrate excellent specific capacity (>1000 mAh/gS) and coulombic efficiency (98%), with >700 mAh/gS remaining after 100 cycles at C/10 rate. This work represents a “bottom-up” or “rational molecular design” approach to Li-S cell design, where the materials, fabrication techniques, and analytical methods are designed de novo based on the unique functional demands of this system.