Insights into the Pseudocapacitive Behavior of Sulfurized Polymer Electrodes for Li-S Batteries.

Practical applications of sulfurized polymer (SP) materials in Li-S batteries (LSBs) are often written off due to their low S content (≈35 wt%). Unlike conventional S /C composite cathodes, SP materials are shown to function as pseudocapacitors with an active carbon backbone using a comprehensive array of tools including in situ Raman and electrochemical impedance spectroscopy. Critical metric analysis of LSBs containing SP materials with an active carbon skeleton shows that SP cathodes with 35 wt% S are suitable for 350 Wh kg target at the cell level if S loading >5 mg cm , electrolyte-to-sulfur ratio <2 µL mg , and negative-to-positive ratio <5 can be achieved.