Fluorinated Benzimidazole‐Linked Highly Conjugated Polymer Enabling Covalent Polysulfide Anchoring for Stable Sulfur Batteries

Abstract

AbstractSulfur is one of the most abundant and economical elements in the p‐block family and highly redox active, potentially utilizable as a charge‐storing electrode with high theoretical capacities. However, its inherent good solubility in many electrolytes inhibits its accessibility as an electrode material in typical metal‐sulfur batteries. In this work, the synthetically designed fluorinated porous polymer, when treated with elemental sulfur through a well‐known nucleophilic aromatic substitution mechanism (SNAr), allows for the covalent integration of polysulfides into a highly conjugated benzimidazole polymer by replacing the fluorine atoms. Chemically robust benzimidazole linkages allow such harsh post‐synthetic treatment and facilitate the electronic activation of the anchored polysulfides for redox reactions under applied potential. The electrode amalgamated with sulfurized polymer mitigates the so‐called polysulfide shuttle effect in the lithium‐sulfur (Li−S) battery and also enables a reversible, more environmentally friendly, and more economical aluminum‐sulfur (Al−S) battery that is configured with mostly p‐block elements as cathode, anode, and electrolytes. The improved cycling stabilities and reduction of the overpotential in both cases pave the way for future sustainable energy storage solutions.