Toward practical lithium-sulfur batteries

As one of the most promising energy-storage devices, lithium-sulfur batteries (LSBs) have been intensively studied and are currently on the edge of practical applications. Ampere hour (A h) level pouch cells are being prepared; however, they still face multiple challenges such as a low practical energy density, short cycle life, and underlying safety issues. The main reasons for these are due to the contradictions between the battery kinetics and electrolyte/sulfur (E/S) ratio, while the utilization of the metal lithium anode also raises possible dendrite concerns. In this review, we summarize the strategy to realize high-loading cathodes and a lean electrolyte for LSBs. In addition, solid-state LSBs are briefly discussed. Hopefully, this work may promote further advances in practical Li-S batteries. A cathode with an areal capacity of more than 5 mA h cm-2 is crucial for practical Li-S batteries. Besides, reducing the electrolyte weight ratio, in both liquid and solid-state Li-S batteries, is also important.