Study on the electrochemical reaction mechanism of non-corrosive and long-life rechargeable aluminum battery

Due to the high volumetric capacity, low cost and high security, rechargeable aluminum batteries (RABs) become potential candidates for energy applications. However, the high charge density of Al³⁺ leads to strong coulombic interactions with anions and cathodes, resulting in slow kinetics diffusion and irreversible collapse of the cathode structure. Meanwhile, the commonly used electrolyte AlCl₃-based ionic liquids have serious corrosion on the battery components and are prone to side reactions. The above problems lead to low capacity and poor cycling stability. Here, the reduced graphene oxide (rGO) cathode with three-dimensional porous network was prepared by a simple and scalable method. The lamellar edges and oxygen-containing group defects of rGO synergistically provide abundant ion storage sites and enhance the kinetic. Matching with non-corrosive electrolyte 0.5 M Al(OTF)₃/[BMIM]OTF and Al metal, we constructed a high-performance battery, Al||rGO-150, with good cycling stability and discharge capacity of 80 mAh g⁻¹ after 3200 cycles. Quasi-in situ physicochemical characterization indicate that the ion storage mechanism is co-dominated by diffusion and capacitance. The capacity consists of the insertion of Al-based species cations as well as adsorption and insertion of OTF^- and [BMIM]⁺ synergistically. This work promotes the fundamental and applied research on RABs.