A long-life and safe lithiated graphite-selenium cell with competitive gravimetric and volumetric energy densities

Abstract

Lithium-selenium (Li-Se) battery is a promising system with high theoretical gravimetric and volumetric energy densities, while its long-term cyclability is hard to realize, especially when a practical Se cathode with high Se content, high Se loading, and high density is employed. The main obstacles are the sluggish conversion kinetics of the dense Se cathodes and the continuous deterioration of the Li-metal anodes. Here, by introducing an acetonitrile (AN)-based electrolyte and replacing the Li electrode with a lithiated graphite, we successfully build a hybrid conversion-intercalation system using a high-content (80 wt%), decent-loading (3.0 mg cm−2), and low-porosity (44%) Se cathode. The as-designed lithiated graphite||Se (LG||Se) cell demonstrated a high Se utilization (97.4%), a long cycle life (3000 cycles), and an ultrahigh average Coulombic efficiency (99.98%). The cell also works well under lean-electrolyte (2 μL mg−1) condition and shows outstanding safety performance in the nail-penetrating test. The combination affords the competitive comprehensive performances, including high volumetric and gravimetric energy densities, long cycling life, and superb safety of the LG||Se cell. In addition, with a newly-designed three-electrode pouch cell, the lithiation of the graphite anodes could be done with an in-situ lithiation process, indicating the high potential of the as-proposed LG||Se cell for the practical applications.