Boosting the “Solid–Liquid–Solid” Conversion Reaction via Bifunctional Carbonate‐Based Electrolyte for Ultra‐long‐life Potassium–Sulfur Batteries
Shufen Ye, Nan Yao, Xiang Chen, Mingze Ma, Lifeng Wang, Zhihao Chen, Yu Yao, Qiang Zhang, Yan Yu
Abstract
Abstract Potassium–sulfur (K−S) batteries have attracted wide attention owing to their high theoretical energy density and low cost. However, the intractable shuttle effect of K polysulfides results in poor cyclability of K−S batteries, which severely limits their practical application. Herein, a bifunctional concentrated electrolyte (3 mol L −1 potassium bis(trifluoromethanesulfonyl)imide in ethylene carbonate (EC)) with high ionic conductivity and low viscosity is developed to regulate the dissolution behavior of polysulfides and induce uniform K deposition. The organic groups in the cathode electrolyte interphase layer derived from EC can effectively block the polysulfide shuttle and realize a “solid–liquid–solid” reaction mechanism. The KF‐riched solid‐electrolyte interphase inhibits K dendrite growth during cycling. As a result, the achieved K−S batteries display a high reversible capacity of 654 mAh g −1 at 0.5 A g −1 after 800 cycles and a long lifespan over 2000 cycles at 1 A g −1 .