Carbon–Sulfur Composites from Cylindrical and Gyroidal Mesoporous Carbons with Tunable Properties in Lithium–Sulfur Batteries

• Published in: Chemistry of materials 2015-05, Vol.27 (9), p.3349-3357
• Main Authors: Werner, Jörg G, Johnson, Samuel S, Vijay, Vishal, Wiesner, Ulrich
• Format: Article
• Language: English
• ISSN: 0897-4756; 1520-5002
• DOI: 10.1021/acs.chemmater.5b00500

Sulfur is a high-potential candidate for next generation electrical energy storage due to its abundance, low cost, and nontoxicity. The electrically insulating property of sulfur and lithium sulfide and the solubility of polysulfides in the electrolyte, however, pose great challenges for the realization of long-lasting lithium–sulfur batteries for commercial applications. In recent years, much attention has been focused on mesoporous carbon–sulfur composites as cathode material. Fundamental studies on the performance of such electrodes correlated to systematic variations of structural and porosity characteristics of the carbons remain elusive, however. In this work a variety of block copolymer (BCP) derived mesoporous carbons were studied with uniform and tunable pore sizes as sulfur hosts. Morphologies included hexagonally packed cylinders and co-continuous gyroids, with one- and three-dimensional porosity, respectively. Dependence of the cyclability of carbon–sulfur composites was tested on mesopore size, morphology, and carbonization temperatures of up to 1600 °C. Results demonstrate the significant impact of the carbon properties related to the carbonization temperature, such as heteroatom content, on the capacity retention of carbon–sulfur cathodes, while morphological parameters and mesopore sizes (between 15 and 40 nm) of carbons studied here have little influence on performance. The high-temperature-derived gyroidal mesoporous carbons (1600 °C) exhibited remarkable structural stability toward activation. This allowed for the introduction of nanopores (