Interface Engineering of Lithium Metal Anodes via a Polysulfide-Phosphosiloxane Additive for Durable Li–S Batteries

Lithium-sulfur batteries (LSBs) are a promising next-generation energy storage option due to their excellent theoretical energy density. Nevertheless, issues such as lithium dendrite growth and SEI layer instability hinder their commercialization. This study introduced LPSP-PDMS, a polyphosphosiloxane polysulfide polymer, as an electrolyte additive to enhance the lithium metal anode interfaces. The <i>in situ</i> interfacial reaction triggers the formation of a hybrid SEI, composed of inorganic substances such as lithium chloride (LiCl) and Li-Si-O, as well as methyl-containing organic species. This structure acts as a rigid barrier and efficient ion conductor, enabling dendrite-free lithium deposition. Among the series of materials, Li₃PS_8.5-PDMS exhibits excellent properties. A lithium symmetrical cell with it has 1000 h cycle stability at 1 mA cm^-2 with only 23 mV overpotential. A lithium-sulfur full cell also has better cycling and rate capacity, retaining 710.5 mA h g^-1 following 300 cycles at 1 C. This work demonstrates an effective method for designing functional electrolyte additives toward high-performance and safe LSBs.