Synergism of Flame-Retardant, Self-Healing, High-Conductive and Polar to a Multi-Functional Binder for Lithium–Sulfur Batteries

In this work, a multifunctional binder with self-healing, flame retardant, high conductivity, and abundant polar groups is prepared by the free radical polymerization method and applied to lithium–sulfur (Li-S) batteries to achieve high safety and exceptional electrochemical performance. The self-healing characteristic of binder induced by intermolecular hydrogen bonds and S-S dynamic covalent bonds can repair volume expansion cracks. The polar groups and excellent conductivity endue binder with strong chemisorption on polysulfides and fast charge transportation, which can effectively inhibit the shuttle effect and accelerate polysulfides redox kinetics. More important, the considerable flame retardant performance of binder can improve the safety of the Li-S batteries. As a result, the Li-S cells using FHCP binder deliver an outstanding cycle stability of a high-capacity retention rate of 85% after 100 cycles at 0.2 C, and a high reversible area specific capacity of 5.25 mAh cm^–2 at a sulfur loading of 4.72 mg cm^–2 and a correspondingly lean electrolyte condition (E/S ratio = 6 µL mg^–1).