Selenium and Selenium–Sulfur Chemistry for Rechargeable Lithium Batteries: Interplay of Cathode Structures, Electrolytes, and Interfaces

In the search for a transformative new energy storage system, the rechargeable Li/sulfur battery is considered as one of the promising candidates due to its much higher energy density and lower cost than state-of-the-art lithium-ion batteries. However, the insulating nature of sulfur and the dissolution of intermediary polysulfides into the electrolyte significantly hinder its practical application. Very recently, selenium and selenium–sulfur systems have received considerable attention as cathode materials for rechargeable batteries owing to the high electronic conductivity (20 orders of magnitude higher than sulfur) and high volumetric capacity (3254 mAh/cm 3 ) of selenium. In this Perspective, we present an overview of the implications of employing selenium and selenium–sulfur systems with different structures and compositions as electroactive materials for rechargeable lithium batteries. We also show how the cathode structures, electrolytes, and electrode–electrolyte interfaces affect the electrochemistry of Se- and Se–S -based cathodes. Furthermore, suggestions are provided on paths for future development of these cathodes.