Exploring an Aluminum Ion Battery Based on Molybdite as Working Electrode and Ionic Liquid as Electrolyte

Abstract

Nowadays rechargeable aluminum batteries are envisaged as a future alternative to lithium ion batteries. However, the development of electrodes and non-aqueous electrolyte solutions for aluminum batteries is still a great challenge. Layered-type molybdite (α-MoO3) is studied here as a positive electrode for Al metal battery and ionic liquid is used as electrolyte solution. The observed maximum gravimetric capacity is 100 mAh g−1, although only a few discharge-charge cycles were successfully carried out and the capacity falls quickly. According to electrochemical, XRD, NMR, microanalysis and XPS results, aluminum cation is intercalated in the interlayer space (van der Waals gap) between the octahedron layers (MoO6) while the main framework is preserved. Because of the intercalation of aluminum and the reduction of molybdenum, the interlayer spacing of AlxMoO3 is reversibly increased compared to pristine molybdite. The intercalation of aluminum into molybdite is a slow process and rather limited to the region near the surface of the particles.