Comprehensive investigation of AlCl3-based electrolytes for rechargeable aluminum-ion battery

Due to the high reversibility of the aluminum deposition/dissolution process, aluminum chloride-based room temperature molten salts exhibit excellent electrochemical performance as the electrolytes of rechargeable aluminum-ion batteries. Aluminum chloride-1-ethyl-3-methylimidazole chloride (AlCl3-EMImCl), AlCl3-acetamide and AlCl3-urea systems are considered as the ideal electrolytes for aluminum-graphite batteries. To better develop and apply those electrolytes, the effects of three electrolytes on the electrochemical performance of aluminum-graphite batteries were studied, comprehensively. AlCl3-EMImCl electrolyte exhibits excellent rate capability and coulombic efficiency. While the AlCl3-amide systems only provide one-third capacity of AlCl3-EMImCl, and the coulombic efficiency is only about 90% at lower rates. The significant difference between the electrochemical properties of AlCl3-based electrolytes is related to the kinetics of ion transport and diffusion between the interface of electrolyte and cathode.