Polymer-Based Solid-State Electrolytes For Lithium–Sulfur Batteries

Lithium–sulfur (Li–S) batteries offer substantial theoretical energy density gains over Li-ion batteries (LIBs), a crucial factor for transportation electrification. In addition, sulfur is an earth-abundant, inexpensive material obtainable from multiple resources; thus, Li–S batteries are envisioned to provide environmentally sustainable solutions to the growing demand for energy storage. A critical roadblock to the realization of commercial Li–S batteries is the formation of polysulfides and their secondary reactions with liquid organic electrolytes, resulting in low Coulombic efficiency for charging and fast self-discharge rates. The realization of solid-state electrolytes for Li–S batteries provides potential pathways to address the safety concerns of liquid electrolytes and inhibit the formation of polysulfides and/or prevent their diffusion into the anode electrode. However, current solid-state electrolytes are limited by low ionic conductivity, inadequate electrode interfacial compatibility, and restricted electrochemical windows. Composite materials employing polymers embedded with anion salts and filler particles offer a potential solution to circumvent the inherent limitations of inorganic solid-state electrolytes. This review discusses the status of polymer-based electrolytes for Li–S batteries and outlines current methods for their fabrication, their transport characteristics, and ongoing research aimed at overcoming material properties hindering the development of all-solid-state Li–S batteries.