Review - Li metal anode in working lithium-sulfur batteries

Due to the high theoretical energy density of 2600 Wh kg^-1, lithium-sulfur batteries are strongly regarded as the promising nextgeneration energy storage devices. However, the practical applications of lithium-sulfur batteries are challenged by several obstacles, including the low sulfur utilization and poor lifespan, which are partly attributed to the shuttle of lithium polysulfides and lithium dendrite growth in working lithium-sulfur batteries. Suppressing lithium dendrite growth is a necessary step not only for a safe and efficient Li metal anode, but also for a high capacity cell with a high Coulombic efficiency. Herein we review the lithium metal anode protection in a polysulfide-rich environment, relative to most reviews on lithium metal anode without considering the effect of lithium polysulfides in lithium metal batteries. Firstly, the importance and dilemma of Li metal anode issues in lithium-sulfur batteries are underscored, aiming to arouse the attentions to Li metal anode protection. Specific attentions are paid to the surface chemistry of Li metal anode in a polysulfide-rich lithium-sulfur battery. Next, the proposed strategies to stabilize solid electrolyte interface and protect Li metal anode are included. Finally, a general conclusion and a perspective on the current limitations, as well as recommended future research directions of Li metal anode in lithium-sulfur batteries are presented.