Multifunctional Sandwich-Structured Electrolyte for High-Performance Lithium-Sulfur Batteries.

Due to its high theoretical energy density (2600 Wh kg), low cost, and environmental benignity, the lithium-sulfur (Li-S) battery is attracting strong interest among the various electrochemical energy storage systems. However, its practical application is seriously hampered by the so-called shuttle effect of the highly soluble polysulfides. Herein, a novel design of multifunctional sandwich-structured polymer electrolyte (polymer/cellulose nonwoven/nanocarbon) for high-performance Li-S batteries is demonstrated. It is verified that Li-S battery with this sandwich-structured polymer electrolyte delivers excellent cycling stability (only 0.039% capacity decay cycle on average exceeding 1500 cycles at 0.5 C) and rate capability (with a reversible capacity of 594 mA h g at 4 C). These electrochemical performances are attributed to the synergistic effect of each layer in this unique sandwich-structured polymer electrolyte including steady lithium stripping/plating, strong polysulfide absorption ability, and increased redox reaction sites. More importantly, even with high sulfur loading of 4.9 mg cm, Li-S battery with this sandwich-structured polymer electrolyte can deliver high initial areal capacity of 5.1 mA h cm. This demonstrated strategy here may open up a new era of designing hierarchical structured polymer electrolytes for high-performance Li-S batteries.