Designing a high-loading sulfur cathode with a mixed ionic-electronic conducting polymer for electrochemically stable lithium-sulfur batteries

Abstract

As one of the most widely regarded candidates for energy storage, Li-S are attractive as due to their high theoretical energy density. To be considered for practical viability, a high active material loading must be considered. This is limited by the insulating nature of the active material, amplified polysulfide shuttling, and the cracking in the cathode due to the large volume change between charge and discharge products. A copolymer is prepared with poly(styrene 4-sulfonate) (PSS) and polypyrrole (PPy) to enable rational design of high sulfur loading Li-S batteries. The copolymer with a mixed ionic-electronic conductivity (MIEC) facilitates cooperative charge transport and stabilization during cycling, allowing a high sulfur loading of 6.0 mg cm−2. The resulting Li-S cell displays a high initial discharge capacity of 1108 mA h g−1 at a C/10 rate with a capacity retention of 64% after 200 cycles. The copolymer with MIEC offers a promising approach for realizing practical, long-life Li-S batteries.