High Mass Loading Li-S Batteries Catalytically Activated by Cerium Oxide: Performance and Failure Analysis under Lean Electrolyte Conditions.

Increasing sulfur mass loading and minimizing electrolyte amount remains a major challenge for the development of high energy density Li-S batteries, which needs to be tackled with combined efforts of materials development and mechanistic analysis. In this work, following our most recent identification of the potential-limiting step of Li-S batteries under lean electrolyte conditions, we seek to advance the understanding by extending it to a new catalyst and into the region of high sulfur mass loading. We integrate CeO nanostructures into cotton-derived carbon to develop a multifunctional 3D network that can host a large amount of active material, facilitate electron transport, and catalyze the sulfur lithiation reaction. The resulting S/CeO /C electrode can deliver a stable areal capacity of 9 mAh cm with a high sulfur loading of 14 mg cm at a low electrolyte/sulfur ratio of 5 μL mg . We discover that Li||S/CeO /C cells usually fail during a charging step at high current density, as a consequence of local short circuiting caused by electrochemically deposited Li dendrites penetrating through the separator, a previously overlooked failure pattern distinctive to cells operating under lean electrolyte conditions. This work highlights the importance of developing new material structures and analyzing failure mechanisms in the advancement of Li-S batteries. This article is protected by copyright. All rights reserved.