Developing conductive and electrocatalytic mediators in Li-S batteries

Lithium sulfide (Li-S) batteries are considered a promising and efficient energy storage system because of their high energy density (2600 Wh kg^-1) and low sulfur material cost. However, numerous obstacles to the practical implementation of Li–S batteries remain, including low sulfur conductivity, the shuttle effect, and the requirement for an adequate volume change (80%) of sulfur during charging and discharging operations. These have limited the applicability of Li–S batteries.

Transition metal chalcogenides (TMDs), such as molybdenum diselenide (MoSe₂), have received attention as a viable method for accelerating sulfur redox processes. However, the limited number of active sites in MoSe₂ considerably reduces their overall electrocatalytic performance.

Metal doping into MoSe₂ can improve the electronic conductivity of MoSe₂ and generate defects, creating numerous reactive sites for catalytic reactions. Moreover, polysulfide transformation in the Li–S system can be improved through defect engineering, which can alter the physicochemical and electronic structure to enhance the adsorption and catalytic properties of a material.

Recently, Yutao Dong and Jianmin Zhang (corresponding authors), Mohammed A. Al-Tahan (first author), and others published a manuscript titled "Modulating of MoSe₂ functional plane via doping-defect engineering strategy for the development of conductive and electrocatalytic mediators in Li-S batteries" in the Journal of Energy Chemistry.

The authors demonstrate that introducing iron exposes more active selenium edge sites in MoSe₂, which can selectively adsorb more lithium polysulfides (LiPSs) to minimize the shuttle effect. Moreover, the conductive feature of rGO improves the cell's electrical conductivity and promotes the adsorption of polysulfides via chemical bonding with the functional group of rGO. Therefore, using the Fe-MoSe₂@rGO nanohybrid as a functional plane offers the advantages of high conductivity and effective LiPS adsorption.