Hierarchical sulfur electrodes as a testing platform for understanding the high-loading capability of Li-S batteries

摘要

Lithium-sulfur (Li-S) batteries are considered as an attractive electrochemical energy storage system due to the high theoretical capacity of sulfur (1,675 mA h g(-1)). However, high-loading sulfur cathodes would need to be employed for the Li-S cells to be practical, but the resulting poor cell cyclability and severe electrode degradation hamper their development. Here, we present a hierarchical sulfur cathode as a testing platform for understanding the high-loading capability of Li-S batteries. The hierarchical cathode presents good electrochemical utilization of above 70%, stable cyclability for 500-1,000 cycles, and high sulfur loadings of 4.2-10.0 mg cm(-2). The exploration of the activation and the polysulfide-retention processes of the high-loading cathodes illustrates that the electrochemical stability mainly results from the stabilization of dissolved polysulfides within the cathode region as the electrochemically active catholyte. Therefore, the utilization of stabilized polysulfide migration might be a meaningful opportunity for designing high-loading cathodes and further improving their electrochemical stability and long-term cyclability. (C) 2016 Elsevier B.V. All rights reserved.