Tuning the Solvation Structure of a Weakly Solvating Cyclic Ether Electrolyte for Wide-Temperature Cycling of Lithium-Sulfurized Polyacrylonitrile Batteries

Sulfurized polyacrylonitrile (SPAN) cathodes in high energy-density Li-metal batteries have garnered widespread interest owing to their good cycling stability and moderately high capacities. However, their application is hindered by the low prevalence of advanced electrolytes that can simultaneously mitigate polysulfide generation at the cathode and stabilize the Li-metal anode. Here, a weakly solvating electrolyte is presented, employing a single solvent tetrahydropyran (THP). The solvation structure is effectively tuned by adjusting the salt concentration to stabilize both the Li-metal anode and SPAN cathode. This approach enables stable cycling with high SPAN loadings (approximate to 5 mg cm-2) and lean electrolyte contents (approximate to 5 mu L mgSPAN-1) across a wide temperature range: 0 degrees C, room temperature, and 50 degrees C. A pouch cell with a high SPAN loading and a low electrolyte-to-SPAN (E/SPAN) ratio of 3 mu L mg-1 shows a stable 79.1% capacity retention after 40 cycles. Additionally, THP can be effectively employed in localized high-concentration electrolyte (LHCE) systems to reduce the diluent-to-solvent ratio for greater LHCE viability. The study demonstrates the potential of weakly solvating solvents in Li-SPAN batteries, offering a pathway for their practical application. A weakly solvating single-solvent electrolyte composed of tetrahydropyran stabilizes the lithium-metal anode and sulfurized polyacrylonitrile cathode effectively without the necessity of a fluorinated diluent. It enables stable cycling of Li-SPAN batteries at wide temperature ranges of 0-50 degrees C. image