Graphene-based interlayer boosts Li-S battery performance

Researchers at India's Cochin University of Science and Technology have developed a bifunctional polyaniline/reduced graphene oxide (PRGO) interlayer integrated into a lithium-sulfur (Li-S) battery separator, demonstrating a practical route to mitigating polysulfide shuttling while improving electrochemical performance. Li-S systems offer a theoretical specific capacity of 1675 mAh g−1 and energy density approaching 2600 Wh kg−1, but their commercialization has been hindered by sulfur’s extremely low conductivity (~5×10−30 S cm−1) and the dissolution and migration of lithium polysulfides (LiPSs). These soluble intermediates form during discharge - initially at 2.1–2.4V (long-chain polysulfides, ~25% of capacity, 418 mAh g−1) and then at 1.6–2.1V (short-chain species, ~75%, 1257 mAh g−1) - and readily diffuse toward the lithium anode, causing active material loss and rapid capacity fading. The proposed PRGO interlayer is fabricated via a simple physical mixing process and coated onto one side of a conventional polypropylene separator (using PVDF binder), enabling a dual function design: one side acts as a functional interlayer while the other maintains separator integrity. Structural characterization (XRD, Raman, SEM) confirms successful formation of the composite and its interconnected morphology.Mechanistically, the performance gains arise from complementary roles of the two components. Reduced graphene oxide (RGO) provides a conductive, two-dimensional network with abundant surface sites that physically anchor polysulfides and facilitate electron transport. Polyaniline (PANI), a conductive polymer with conjugated structure and porous morphology, contributes strong chemical adsorption of LiPSs while enabling efficient ion transport through its high void fraction. This combination creates a conductive and chemically active barrier that both traps polysulfides near the cathode and promotes their redox conversion, effectively suppressing the shuttle effect. Researchers at India's Cochin University of Science and Technology have developed a bifunctional polyaniline/reduced graphene oxide (PRGO) interlayer integrated into a lithium-sulfur (Li-S) battery separator, demonstrating a practical route to mitiga... [2704 chars]