Inhibiting Polysulfide Shuttling with a Graphene Composite Separator for Highly Robust Lithium-Sulfur Batteries

Lithium-sulfur (Li-S) batteries are of considerable interest for high-density energy storage. However, the adoption of Li-S batteries to date has been severely plagued by the polysulfide shuttling effect, whereby polysulfide molecules dissolve into the electrolyte and shuttle across the separator to react with the anode materials, leading to a rapidly fading capacity. Herein, by directly coating a thin layer of reduced graphene oxide (rGO)/sodium lignosulfonate (SL) composite on the standard polypropylene (PP) separator, we produce a rGO@SL/PP separator with abundant negatively charged sulfonic groups in the porous lignin network, which effectively suppress the translocation of the negatively charged polysulfide (PS) ions without compromising the transport of positively charged Li+ ions. Using the rGO@SL/PP separator, we demonstrate a highly robust Li-S battery with a capacity retention of 74% over 1,000 cycles. This study defines an effective strategy to inhibit the PS shuttling effect for highly robust Li-S batteries. Lithium-sulfur (Li-S) batteries are of considerable interest for high-density energy storage. However, the adoption of Li-S batteries to date has been severely plagued by the polysulfide shuttling effect, whereby polysulfide molecules dissolve into the electrolyte and shuttle across the separator to react with the anode materials, leading to a rapidly fading capacity. Herein, by directly coating a thin layer of reduced graphene oxide (rGO)/sodium lignosulfonate (SL) composite on the standard polypropylene (PP) separator, we produce a rGO@SL/PP separator with abundant negatively charged sulfonic groups in the porous lignin network, which effectively suppress the translocation of the negatively charged polysulfide (PS) ions without compromising the transport of positively charged Li+ ions. Using the rGO@SL/PP separator, we demonstrate a highly robust Li-S battery with a capacity retention of 74% over 1,000 cycles. This study defines an effective strategy to inhibit the PS shuttling effect for highly robust Li-S batteries.