3D porous reduced graphene cathode and non-corrosive electrolyte for long-life rechargeable aluminum batteries

Owing to their high volumetric capacity, low cost and high safety, rechargeable aluminum batteries have become promising candidates for energy applications. However, the high charge density of Al³⁺ leads to strong coulombic interactions between anions and the cathode, resulting in sluggish diffusion kinetics and irreversible collapse of the cathode structure. Furthermore, AlCl₃-based ionic liquids, which are commonly used as electrolytes in such batteries, corrode battery components and are prone to side reactions. The above problems lead to low capacity and poor cycling stability. Herein, we propose a reduced graphene oxide (rGO) cathode with a three-dimensional porous structure prepared using a simple and scalable method. The lamellar edges and oxygen-containing group defects of rGO synergistically provide abundant ion storage sites and enhance ion transfer kinetics. We matched the prepared rGO cathode with noncorrosive electrolyte 0.5 mol·L⁻¹ Al(OTF)₃/[BMIM]OTF and Al metal to construct a high-performance battery, Al||rGO-150, with good cycling stability for 2700 cycles. Quasi-in-situ physicochemical characterization results show that the ion storage mechanism is codominated by diffusion and capacitance. The capacity consists of the insertion of Al-based species cations as well as synergistic adsorption of Al(OTF)_x^(3−x)+ (x < 3) and [BMIM]⁺. The present study promotes the fundamental and applied research on rechargeable aluminum batteries.