A High Capacity Aluminum-Ion Battery Based on Imidazole Hydrochloride Electrolyte

Aluminum-ion batteries (Al-ion batteries) have become a potential energy storage system, owing to their excellent cycling performance, three-electron-redox properties, and safety performance. Until now, great progress has been made in Al-ion batteries. However, the Al-ion battery system still encounters various problems, such as high electrolyte price, harsh working environment, low discharge platforms, and inferior capacity. Here, we prepared a novel Al-ion battery with AlCl₃/Imidazole hydrochloride (ImidazoleHCl) as the electrolyte, aluminum as the negative electrode, and commercial graphite as the positive electrode. The battery achieves a high specific discharge capacity of 129 mA h g⁻¹ at a current density of 0.5 A g⁻¹ and 105 mA h g⁻¹ with a high coulombic efficiency of 99 % at the current density of 4 A g⁻¹ after 1000 cycles. The mechanism of AlCl₄⁻ intercalation/de-intercalation is proved by Raman, XRD and EDS studies. ImidazoleHCl is a promising electrolyte and this work provides a new insight for the Al-ion battery system.