Enhanced Electrochemical Kinetics on Conductive Polar Mediators for Lithium-Sulfur Batteries

• Published in: Angewandte Chemie International Edition 2016-10, Vol.55 (42), p.12990-12995
• Main Authors: Peng, Hong-Jie, Zhang, Ge, Chen, Xiang, Zhang, Ze-Wen, Xu, Wen-Tao, Huang, Jia-Qi, Zhang, Qiang
• Format: Article
• Language: English
• Subjects: Chemical precipitation; Chemical reactions; Chemisorption; Conductors; Dioxides; Electrical conductivity; Electrical resistivity; Electrochemical analysis; Electrochemistry; Energy storage; Flux density; Graphene; Intermediates; Lithium; Lithium sulfur batteries; Nanoparticles; polysulfides; porous graphene frameworks; Reaction kinetics; shuttle effect; Storage batteries; Sulfides; Sulfur; Titanium carbide
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201605676

Lithium–sulfur (Li–S) batteries have been recognized as promising substitutes for current energy‐storage technologies owing to their exceptional advantage in energy density. The main challenge in developing highly efficient and long‐life Li–S batteries is simultaneously suppressing the shuttle effect and improving the redox kinetics. Polar host materials have desirable chemisorptive properties to localize the mobile polysulfide intermediates; however, the role of their electrical conductivity in the redox kinetics of subsequent electrochemical reactions is not fully understood. Conductive polar titanium carbides (TiC) are shown to increase the intrinsic activity towards liquid–liquid polysulfide interconversion and liquid–solid precipitation of lithium sulfides more than non‐polar carbon and semiconducting titanium dioxides. The enhanced electrochemical kinetics on a polar conductor guided the design of novel hybrid host materials of TiC nanoparticles grown within a porous graphene framework (TiC@G). With a high sulfur loading of 3.5 mg cm−2, the TiC@G/sulfur composite cathode exhibited a substantially enhanced electrochemical performance. Li–S batteries: The electrochemical reaction kinetics of reversible polysulfide interconversion and Li2S nucleation/precipitation are substantially enhanced on the conductive and polar surface of titanium carbide, guiding the design of advanced host materials towards high‐energy and stable Li–S batteries.