Engineering of Li+-selective quasi-solid electrolytes via zwitterion and poly(ethylene glycol) co-grafting on poly(arylene ether sulfone) for high-performance lithium–sulfur batteries

Abstract

The creation of a highly efficient lithium-ion-conductive solid and/or quasi-solid electrolyte with effective polysulfide (PS) suppression is essential for stable lithium–sulfur (Li–S) batteries. This study presents a self-assembled quasi-solid electrolyte formed by co-grafting zwitterion (ZW) and poly(ethylene glycol) (PEG) segments onto a durable poly(arylene ether sulfone) (PAES) backbone, denoted as PAES-co-(ZW/PEG)₂. Within the robust PAES framework, Li-ion conductive (ZW/PEG) domains are generated through phase separation assisted by an ionic liquid and ethylene carbonate, ensuring both excellent ionic conductivity and mechanical integrity. The ZW segments effectively restrict PS migration and promote selective Li-ion transport via electrostatic interactions between delocalized anionic sites and Li-ions. The PAES-co-(ZW/PEG)₂ membrane exhibits a high Li⁺ transference number (0.752), superior ionic conductivity (1.58 mS cm⁻¹), and favorable mechanical strength (Young's modulus: 15 MPa; tensile strength: 1.8 MPa). Furthermore, it provides remarkable PS-blocking performance (∼3.418 × 10⁻⁵ cm² s⁻¹) and excellent oxidative stability (5.28 V). Li–S cells employing this electrolyte demonstrate stable cycling over 350 cycles with 93% capacity retention and outstanding rate capability up to 5 C, indicating strong potential for advanced Li–S battery systems.