Facet-Engineered Tungsten Disulfide for Promoting Polysulfide Electrocatalysis in Lithium-Sulfur Batteries

Area of Science:

• Materials Science
• Electrochemistry
• Energy Storage

Background:

• Lithium-sulfur (Li-S) batteries offer high theoretical energy density but are limited by slow polysulfide redox kinetics.
• Distinct crystallographic facets of electrocatalysts can influence reaction rates in Li-S battery chemistry.

Purpose of the Study:

• To investigate the role of the (100) facet of tungsten disulfide (WS2) as an electrocatalyst for polysulfide redox kinetics in Li-S batteries.
• To compare the performance of in situ generated e-WS2 with ex situ synthesized bulk WS2.

Main Methods:

• Electrochemical pulverization to generate in situ e-WS2.
• Transmission electron microscopy (TEM) for facet analysis.
• Density functional theory (DFT) calculations to understand electronic properties.

Main Results:

• The (100) facet of e-WS2 exhibited unprecedentedly low onset potentials for Li2S8 and Li2S2 reduction (2.52 V and 2.32 V vs Li/Li+).
• TEM confirmed the dominance of the (100) facet in e-WS2, contrasting with the pronounced (002) facet in bulk WS2.
• DFT analysis revealed metallic-like behavior of the (100) facet, crucial for enhanced kinetics.

Conclusions:

• The (100) facet of e-WS2 is a highly effective electrocatalyst for promoting polysulfide redox kinetics in Li-S batteries.
• Electrochemical pulverization is a viable method for generating catalytically active WS2 facets.
• The findings suggest potential applications for e-WS2 in hydrogen evolution reaction, photocatalysis, and CO2 reduction.