Enhanced reliability of aluminum–sulfur batteries with cost-effective ionic liquid electrolyte and sulfur/graphite cathode

Abstract

The low coulombic efficiency and mild conductivity have impeded the commercialization of sulfur-based batteries despite pairing with high energy density and low-cost aluminum anodes. In this study, we investigated cost-effective electrolyte confinement of the sulfur cathode to an Al/S@Gf battery, which employed a sulfur-graphite (S@Gf) cathode, an aluminum metal anode, and 1-ethyl-3-methyl imidazolium chloride (EMImCl):AlCl₃ as an electrolyte. The Al/EMImCl:AlCl₃/S@Gf battery exhibited remarkable performance in terms of rate capability and cycle life, delivering a high capacity of 1281 mA h g⁻¹ at a current density of 300 mA g⁻¹ with 90% coulombic efficiency (CE); additionally, it was stable at 800 mA g⁻¹ withdrawing current. By employing an embedding technique to incorporate sulfur particles onto the graphite, we emulated previously observed glitches, such as capacity degradation and poor conductivity resulting in the accumulation of insoluble discharge products hindering ion diffusion. We demonstrated the potential of graphite to enhance the capability of holding sulfur for creating cells with repeatable, stable, and long-lasting charge storage features. This paper elucidates the interactions between carbon, sulfur, and aluminum electrolytes, and sheds light on their respective roles in the fundamental charge-storage process of aluminum–sulfur batteries.