In‐Built Compatible Electrode‐Electrolyte Interphases for Quasi‐Solid‐State Li‐SPAN Batteries

Lithium-sulfur batteries have been regarded as a promising candidate for next-generation energy storage systems owing to their high energy density and low cost. Sulfurized polyacrylonitrile (SPAN) as a cathode material has received wide interest due to the solid-solid conversion mechanism, while the Li-SPAN cell performance has been limited by the notorious issue of lithium metal anode. Developing solid-state electrolytes for lithium-sulfur batteries with favorable electrode-electrolyte compatibility is urgently desired. Herein, we demonstrate a dual-interface optimization strategy through in-situ polymerization interface construction, which synergistically enhances interfacial compatibility between the solid polymer electrolyte (SPE) and both the lithium metal anode and SPAN cathode. The initiator pre-buried in the SPE triggers the in-situ polymerization of 1,3-dioxolane (DOL) at the interface, thereby greatly reducing the electrode/electrolyte interfacial impedance. Additionally, the released fluoroethylene carbonate (FEC) into the poly-DOL interface could further reduce the impedance and enhance the interface stability during cycling, simultaneously preventing the dissolution of polysulfides, owing to the inorganic-rich and dense cathode electrolyte interphase formed on SPAN. As a result, the Li-SPAN cell could operate more than 200 cycles at 0.5C with a capacity retention of 90%. We believe that this strategy provides prospects for the development of high-energy solid-state lithium-sulfur batteries.