Aluminum Acetylacetonate-Confined In-Situ Polymer as Dynamic Active Medium for Sustainable Solid-State Lithium–Sulfur Batteries

Solid polymer electrolyte (SPE)-based lithium–sulfur (Li–S) batteries attract significant interest due to their high theoretical energy densities and enhanced safety profiles. However, the clogging of the cathode-SPE interface with ″dead″ lithium polysulfide (LiPS) is the core failure mechanism of the SPE-based Li–S battery. This induces a sluggish, irreversible electrochemical environment, hindering redox processes and limiting the practical implementation of high-energy-density solid-state Li–S batteries (SSLSBs). To address this problem, this study proposes the generation of a dynamic active medium (DAM) electrolyte system at the cathode interface. Based on the coordination effect between aluminum acetylacetonate and 1,3-dioxolane (DOL), this system is introduced between the cathode and in situ-polymerized polyDOL-based SPE, synergistically realizing three functions: (1) optimizing the electrode–electrolyte interfacial compatibility, (2) adsorbing and reactivating the LiPS accumulated at the interface, and (3) reducing the energy barriers of the S redox reactions and accelerating the sulfide conversion kinetics. This approach enables the SSLSB to reach a high energy density of 347 Wh kg –1 at a high S loading of 4.5 mg cm –2 . The pouch cell configuration maintains a capacity retention rate as high as 85.3% after 80 cycles. Moreover, this interfacial DAM strategy provides an innovative engineering concept to suppress the accumulation of LiPS in SSLSBs.