A low-cost deep eutectic solvent electrolyte for rechargeable aluminum-sulfur battery

Aluminum-sulfur (Al-S) battery is a promising candidate of next generation rechargeable batteries owing to its high theoretical energy density, high safety and low cost, but currently greatly impeded by the shortage of high-performance and cost-effective electrolytes. In this work, a low-cost deep eutectic solvent, i.e., AlCl3/acetamide, as the electrolyte for reversible room-temperature Al-S battery has been reported. The Al-S battery delivers an initial capacity above 1500 mA h g−1 and good rate performance, which is most probably caused by the presence of AlCl4−, Al2Cl7− and [AlCl2·(acetamide)2]+ ions as indicated by spectroscopic analysis. Furthermore, X-ray photoelectron spectroscopy on the discharged sulfur cathode suggests the presence of aluminum sulfides including Al2S3 as electrochemical conversion products. Density functional theory calculations on the energy barriers provide insights into the electrochemical reaction pathways. This AlCl3/acetamide based Al-S battery presents a promising prospect for high-performance and low-cost energy storage system in future.