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

Abstract 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 AlCl 3 /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 AlCl 4 − 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.