A Lithium-Ion Conducting Polysulfide Polymer for Flexible Batteries

An organopolysulfide polymer is rationally designed by attaching polysulfide chains adjacent to a Li-ion solvating, ether-based backbone through the condensation reaction between 2,2′-(ethylenedioxy)diethanethiol (EDDT) and sulfur. The resulting polymer referred to as pEDDT-S outperforms sulfur in high-rate tests owing to the proximity of the ion-transport channels and the reacting polysulfides. Significant improvements are also seen in long-term stability as well as when operating under high-loading and lean-electrolyte regimes. The pEDDT-S is also extremely flexible with the capability to tolerate 1830% strain before failure. The simultaneous improvement in sulfur redox and inherent elasticity renders such materials ideal for flexible batteries. A prototype pouch cell was found to operate successfully under repeated bending with an energy density of 695 Wh kg–1 at the cathode level, highlighting the promise of such material design. The optimization and development of such organopolysulfide polymers could enable the proliferation of wearable electronic devices.