Elemental Selenium for Electrochemical Energy Storage

To meet the increasing demand for electrochemical energy storage with high energy density, elemental Se is proposed as a new attractive candidate with high volumetric capacity density similar to that of S. Se is chemically and electrochemically analogous to S to a large extent but is saliently featured owing to its semiconductivity, compatibility with carbonate-based electrolytes, and activity with a Na anode. Despite only short-term studies, many advanced Se-based electrode materials have been developed for rechargeable Li batteries, Na batteries, and Li ion batteries. In this Perspective, we review the advances in Se-based energy storage materials and the challenges of Li-Se battery in both carbonate-based and ether-based electrolytes. We also discuss the rational design strategies for future Se-based energy storage systems based on the strengths and weaknesses of Se.