Composite protective coating on lithium metal anodes for polysulfide shielding in lithium-sulfur batteries

• • Protected LMAs survive direct water contact and 35% relative humidity air exposure without degradation, whereas bare Li corrodes instantly; this eliminates the need for costly dry-room manufacturing (dew point < −40 °C) and reduces transportation safety risks. • • In Li-S cells with 4.5 mg cm−2 sulfur loading, the composite coating enables 61.1% capacity retention after 300 cycles, corresponding to a decay rate of 0.13% per cycle; this exceeds typical bare Li retention (<40% over 200 cycles) and approaches the 80% retention threshold required for electric vehicle adoption. • • The FDTS coating provides a hydrophobic barrier with a water contact angle >150°, effectively blocking polysulfide diffusion; this suppresses the parasitic reactions that generate Li2S-rich SEI, reducing active lithium consumption and improving Coulombic efficiency to >99% (vs. <95% for bare Li). • • The layer-by-layer GO film homogenizes Li-ion flux, lowering the overpotential for Li deposition to <20 mV at 1 mA cm−2; this mitigates dendrite growth, extending cycle life beyond 300 cycles, which is critical for meeting the 1000-cycle target for commercial Li-S batteries.