Manipulating Electrocatalytic Polysulfide Redox Kinetics by 1D Core-Shell Like Composite for Lithium-Sulfur Batteries

Although lithium-sulfur batteries have high theoretical energy density of 2600 Wh kg(-1), the sluggish redox kinetics of soluble liquid polysulfide intermediates during discharge and charge is one of the main reasons for their limited battery performance. Designing highly efficient electrocatalysts with a core-shell like structure for accelerating polysulfide conversion is vital for the development of Li-S batteries. Herein, core-shell MoSe2@C nanorods are proposed to manipulate electrocatalytic polysulfide redox kinetics, thereby improving the Li-S battery performance. The 1D MoSe2@C is synthesized via a facile hydrothermal and subsequent selenization reaction. The electrocatalysis of MoSe2 is confirmed by the analysis of symmetric batteries, Tafel curves, changes of activation energy, and lithium-ion diffusion. Density functional theory calculations also prove the low Gibbs free energy of the reaction pathway and the lithium-ion diffusion barrier. Therefore, the Li-S batteries using MoSe2 electrocatalyst exhibit an excellent rate performance of 560 mAh g(-1) at 1 C with a high sulfur loading of 3.4 mg cm(-2) and an areal capacity of 4.7 mAh cm(-2) at a high sulfur loading of 4.7 mg cm(-2) under lean electrolyte conditions. This work provides a deeper insight into regulation of polysulfide redox kinetics in electrocatalysts for Li-S batteries.

Automated summary

In this study, core-shell MoSe2@C nanorods are proposed and investigated as an electrocatalyst to accelerate polysulfide conversion in lithium-sulfur batteries. Experimental results confirm the electrocatalytic properties of MoSe2 and its influence on lithium-ion diffusion. The Li-S batteries using MoSe2 electrocatalyst exhibit excellent performance, with high specific capacity and sulfur loading.