Toward High Performance Lithium-Sulfur Batteries Based on Li2S Cathodes and Beyond: Status, Challenges, and Perspectives

Lithium sulfur (Li-S) batteries are attracting ever-increasing interests as a new generation rechargeable battery system with high energy density and low cost. Li-S batteries will fulfill their theoretical potential if the problem of polysulfides shuttle effect can be solved. Therefore, tremendous efforts have been devoted to overcoming this problem from the aspects of physical confinement and chemisorption of polysulfides. Recently, it is discovered that replacing sulfur cathodes with lithium sulfide (Li2S) can not only largely avoid the volume expansion issue during cycling, but it can also work with anode materials other than lithium metal to eliminate serious safety concerns for traditional Li-S batteries. However, there are many challenges for developing practical Li metal-free Li-S battery systems, because Li2S-based cathode materials are moisture-sensitive and prelithiation of the non-Li metal anode materials is usually required for practical applications. This study reviews the recent advances of Li-S batteries based on Li2S cathode with features of improved safety, high Coulombic efficiency, and high energy density. The electrode activation processes are also discussed, which is critical for achieving high performances. It is anticipated that the extensive efforts will lead to breakthroughs for the development of Li2S cathode -based Li-S batteries.