Stable Cycling of Room-Temperature Sodium-Sulfur Batteries Based on an In Situ Crosslinked Gel Polymer Electrolyte

High-temperature sodium-sulfur battery (HT Na-S) technology has attracted substantial interest in the stationary energy storage sector due to its low cost and high energy density. However, the currently used solid electrolyte (ss-alumina) is expensive and can only be operated at high temperatures, which compromises safety. On the other hand, liquid electrolytes in room temperature sodium-sulfur batteries (RT Na-S) are susceptible to dendrite formation and polysulfide shuttle. Consequently, an electrolyte with both solid (shuttle blocking) and liquid (ionic conductivity) properties to overcome the above-mentioned issues is highly desired. Herein, a high-performance quasi-solid state crosslinked gel polymer electrolyte (GPE) prepared in situ using pentaerythritol triacrylate (PETA) exhibiting high ionic conductivity of 2.33 mS cm(-1) at 25 degrees C is presented. The GPE-based electrolyte shows high stability resulting in a high discharge capacity of >600 mAh g(s)(-1) after 2500 cycles with an average Coulombic efficiency of 99.91%. Density functional theory calculations reveal a weak interaction between the Na+ ions and the oxygen molecules of the PETA moiety, which leads to a facile cation movement. The crosslinked polymer network is tightly connected to the cathode and can confine sulfides, thereby facilitating the conversion process.