An Aqueous, Environmental‐Friendly, and Flame‐Retardant Biomass‐Derived Binder for High‐Safe, High‐Rate, and Long‐Life Lithium–Sulfur Batteries

Abstract Lithium–sulfur batteries demonstrate significant potential as contenders for next‐generation high‐energy storage systems. However, the severe shuttle effect of polysulfides and the likelihood of thermal runaway using sulfur cathode and lithium anode result in swift performance deterioration and associated safety hazards, which significantly hinders their progress. Hence, this study develops a novel RB binder owning multifunctional properties, i.e., accommodating the sulfur cathode volume expansion, suppressing the lithium polysulfides shuttle and lithium dendrite growth, promoting Li ⁺ transfer and reaction kinetics, as well as reducing the sulfur cathode's flammability, to tackle the issues. By using such a novel and functional binder, the lithium–sulfur battery demonstrates a remarkable initial capacity of 1001.6 mAh g ⁻¹ at 1C, along with excellent capacity reversibility, achieving a capacity decay rate of merely 0.027% per cycle at a high rate of 4C. Moreover, even with an increased sulfur load of 5.0 mg cm ⁻² , it sustains an area capacity of ≈3 mAh cm ⁻² after 300 cycles at 0.5 C. This multifunctional water‐soluble binder with flame retardancy provides a competitive choice for realizing high‐rate, high‐safety, and long‐life lithium–sulfur batteries.