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The lithium-sulfur battery is regarded as one of the most promising candidates for lithium-metal batteries with high energy density. However, dendrite Li formation and low cycle efficiency of the Li anode as well as unstable sulfur based cathode still hinder its practical application. Herein a novel electrolyte (1 m LiODFB/EC-DMC-FEC) is designed not only to address the above problems of Li anode but also to match sulfur cathode perfectly, leading to extraordinary electrochemical performances. Using this electrolyte, lithium|lithium cells can cycle stably for above 2000 hours and the average Coulumbic efficiency reaches 98.8 %. Moreover, the Li-S battery delivers a reversible capacity of about 1400 mAh g−1sulfur with retention of 89 % for 1100 cycles at 1 C, and a capacity above 1100 mAh g−1sulfur at 10 C. The more advantages of this cell system are its outstanding cycle stability at 60 °C and no self-discharge phenomena. [ABSTRACT FROM AUTHOR]

A novel hydrophilic polytetrafluoroethylene (PTFE)-supported gel polymer electrolyte (GPE) membrane based on the cross-linked poly(ethylene glycol) and poly(glycidyl methacrylate) block copolymer (PEG–b–PGMA) is successfully prepared by cationic ring-opening polymerization and followed by in situ cross-linking process. The poly(ethylene glycol) side chains of PEG–b–PGMA interact with the liquid electrolyte and hold it inside the membrane, while the hydrophilic and highly-porous PTFE membrane offers mechanical support for the cross-linked GPE. The ionic conductivity of the optimized GPE-3 reaches 1.30×10−3 Scm−1 at 25°C and is high enough to be applied in lithium secondary batteries. The GPE is electrochemically stable up to 4.5V versus Li/Li+. Moreover, the optimized GPE membrane demonstrates non-flammability and good dimensional stability at elevated temperature, which can improve the safety of the cell. The Li/LiFePO4 cell using the GPE-3 exhibits stable cycling behavior and superior rate performance comparable to the cell based on conventional liquid electrolyte. Therefore, the reported GPE is very promising for the use in rechargeable lithium batteries. [ABSTRACT FROM AUTHOR]