Room-Temperature Aluminum-Sulfur Batteries with a Lithium-Ion-Mediated Ionic Liquid Electrolyte

Abstract

Aluminum-sulfur (Al-S) chemistry is attractive for the development of future-generation electrochemical energy storage technologies. However, to date, only limited reversible Al-S chemistry has been demonstrated. This paper demonstrates a highly reversible room-temperature Al-S battery with a lithium-ion (Li+-ion)-mediated ionic liquid electrolyte. Mechanistic studies with electrochemical and spectroscopic methodologies revealed that the enhancement in reversibility by Li+-ion mediation is attributed to the chemical reactivation of aluminum polysulfides and/or sulfide by Li+ during electrochemical cycling. The results obtained with X-ray photoelectron spectroscopy and density functional theory calculations suggest the presence of a Li3AlS3-like product with a mixture of Li2S- and Al2S3-like phases in the discharged sulfur cathode. With Li+-ion mediation, the cycle life of room-temperature Al-S batteries is greatly improved. The cell delivers an initial capacity of ∼1,000 mA hr g−1 and maintains a capacity of up to 600 mA hr g−1 after 50 cycles. Batteries represent an indispensable technology for electrifying the transportation sector and for storing electricity produced from renewable sources. Ambient-temperature non-aqueous sulfur battery chemistries are becoming increasingly appealing for these applications. Although lithium-sulfur batteries have been extensively investigated in recent years, aluminum-sulfur (Al-S) chemistry is more attractive from an economical, sustainability, and safety point of view. However, because of a lack of effective electrolytes, only limited reversibility has been realized so far with Al-S chemistry. This paper presents a lithium-ion mediation strategy for enhancing the reversibility of Al-S chemistry at ambient temperatures. A lithium-ion-mediated ionic liquid electrolyte remarkably improves the electrochemical performance of Al-S batteries. Based on a series of experimental and computational simulation analyses, the relevant mechanisms are presented. Manthiram and colleagues have validated a Li+-ion mediation approach to enhance the electrochemical reversibility of ambient-temperature aluminum-sulfur (Al-S) battery chemistry. They systematically investigated the relevant mechanisms with combined experimental and theoretical methodologies. Al-S chemistry is attractive for the development of high-energy, low-cost, safe, next-generation electrochemical energy storage technologies.