High Performance Lithium–Sulfur Battery with a Multifunctional Organic Nitrogen–Fluorine Compounds-Modified Electrolyte

Abstract

Lithium–sulfur (Li–S) batteries continue to encounter challenges related to the shuttle effect and interfacial issues associated with lithium metal anodes in practical applications. In this study, the multifunctional electrolyte organic nitrogen–fluorine additive 2,5-difluoropyrazine (2,5-DFP) was proposed for Li–S batteries, highlighting its merits from several perspectives. The additive not only facilitates the formation of energy-reducing intermediates during the reaction of sulfur cathode with lithium polysulfides (LiPSs) but also effectively modulates the molecular orbital energy levels of LiPSs and enhances their redox kinetics. The additive can also suppress dendrite growth by forming a dense and smooth organic–inorganic hybrid solid electrolyte interphase (SEI) on the lithium anode such as lithium fluoride. Consequently, the developed cell shows a high capacity of 1215.6 mAh g^–1 and maintains a capacity of 588.1 mAh g^–1 even at a high rate of 4 C. This study demonstrates that 2,5-DFP can serve as a functional electrolyte additive, offering insights for the design of electrolytes for Li–S batteries.