Role and Potential of Metal Sulfide Catalysts in Lithium‐Sulfur Battery Applications

Sulfur has been explored as a cathode active material for post rechargeable batteries because of their various attractive features such as their high theoretical specific capacity which is more than six times that of typical Li‐ion battery (LIB) cathode materials (LiCoO2). Furthermore, as a by‐product of the oil refining process, it is abundant and inexpensive. Despite this, the low electrical conductivity of sulfur and the polysulfide shuttle effect in ether‐based electrolytes has become a major obstacle to the industrialization of lithium‐sulfur (Li−S) batteries. Among them, the polysulfide shuttle effect is the critical limitation to be solved and thus many researchers have been engaged in its solution. This work summarizes a variety of metal sulfide catalysts that have recently attracted attention as additives. In addition, a brief description of the metal sulfides interprets their ability to anchor polysulfides via surface polarity and to act as an electrocatalyst during polysulfide redox reactions. We describe the electrocatalytic activity and anchoring effect of metal sulfides in Li−S batteries and their future possibilities. Li‐S batteries: organic/inorganic supporting materials that can enhance anchoring effects in Li−S batteries are reviewed, including doped carbons, metal oxides and metal sulfides. These materials can effectively coordinate polysulfide intermediate species on the electrochemical reaction sites, increasing cycle retention as well as rate performance. Especially, use of metal sulfides as the electrochemical catalyst is highlighted because of their high polar‐polar interaction characteristic due to preferred edge sites. Guidance for commercializing Li−S batteries is sought by reviewing not just electrochemical catalysis processes like oxygen evolution or reduction reactions, but also traditional petroleum refinement processes like hydrodesulfurization.