Engineering Densely\nPacked Ion-Cluster Electrolytes\nfor Wide-Temperature Lithium–Sulfurized Polyacrylonitrile Batteries

The electrolyte plays an essential role in the advancement\nof lithium–sulfur\nbatteries (LSBs), as it not only transports the charge carriers but\nalso extensively influences sulfur conversion mechanisms and electrode–electrolyte\ninterphases formed on the electrode surface, thereby directly impacting\nbattery performance. However, the majority of existing electrolytes\nsuffer from incompatibility with either the Li anode or the sulfur\ncathode. Here, we develop a densely packed ion-cluster electrolyte\n(DPIE) through the strategic combination of a weakly solvating solvent\nand an inert diluent, resulting in the self-assembly of abundant compact\nion-pair aggregates within its structure. This peculiar solvation\nstructure promotes fast Li<sup>+</sup> desolvation, the formation\nof robust electrode–electrolyte interphases, and the suppression\nof polysulfide dissolution. Leveraging the tailored DPIE, room-temperature\nLi||sulfurized polyacrylonitrile (SPAN) batteries demonstrate 300\nstable cycles with a capacity retention of 97.8% and a steady Coulombic\nefficiency exceeding 99.9%. Even under a limited negative/positive\nareal capacity ratio of four, the Li||SPAN cells exhibit good stability\nover 250 cycles with 97.1% capacity retention. Furthermore, Li||SPAN\nbatteries show impressive stability over a wide temperature range\nspanning from −20 to 60 °C and exhibit reversibility at\n−10 °C over 200 cycles. This electrolyte design enables\nLSBs with prolonged operational lifetimes, rapid charging capabilities,\nand expanded temperature tolerance.