Long-Life and High-Power Sodium-Selenium Batteries Realized by Vanadium Single Atom Catalyzed Cathodes and Tailored Carbonate-Based Electrolytes

Abstract

The practical implementation of resources-abundant sodium-selenium battery (SSB) has been retarded by the low capacity utilization and poor reversibility from the sluggish conversion kinetics of selenides, the notorious polyselenides shuttling effect and the dendritic deposition of sodium metal. This work presents a rational design of vanadium single atom catalyst on nitrogen-doped carbon sheets (V-N-C) as selenium host to address the instability of cathodes. Density function theory calculations reveal the superiority of V-N4 in V-N-C over other transition metal and nitrogen atoms in facilitating the adsorption-diffusion-conversion of polyselenides. Se@V-N-C cathodes deliver a high capacity utilization (603 mAh g−1 at 0.1 C, over 89% of theoretical capacity), excellent reversibility (470 mAh g-1 at 0.1C after 500 cycles), and remarkably high-power cyclability (377 mAh g−1 at 5 C over 1000 cycles). The prolong cycle life can also be originated from our tailored NaPF6 carbonate electrolyte with 1 wt% LiDFBOP additive. The new electrolyte is illustrated to generate inorganic-rich solid electrolyte interphase layers to protect sodium metal anodes from polyselenides corrosion and dendritic deposition at high rates. Fundamental findings in this work present a two-pronged approach to the prevailing challenges in the nascent metal-selenium battery chemistry.

Keywords: Sodium-selenium battery, Polyselenides shuttling, V-N-C single-atomic catalyst, LiDFBOP electrolyte additive