Aluminum batteries: Unique potentials and addressing key challenges in energy storage

The study of electropositive metals as anodes in rechargeable batteries has seen a recent resurgence and is driven by the increasing demand for batteries that offer high energy density and cost-effectiveness. Aluminum, being the Earth's most abundant metal, has come to the forefront as a promising choice for rechargeable batteries due to its impressive volumetric capacity. It surpasses lithium by a factor of four and sodium by a factor of seven, potentially resulting in significantly enhanced energy density. These batteries, now commonly referred to as aluminum-ion batteries, offer numerous advantages. These advantages include the abundance of aluminum, its superior charge storage capacity using Al3+ ions in comparison to Li ions, and a fourfold greater volumetric capacity for Al anodes, all while avoiding the safety concerns associated with alkali metals. Nevertheless, there are challenges to address in pursuing this technology. These challenges encompass the intricate Al3+ intercalation process and the problem of anode corrosion, particularly in aqueous electrolytes. This review aims to explore various aluminum battery technologies, with a primary focus on Al-ion and Al‑sulfur batteries. It also examines alternative applications such as Al redox batteries and supercapacitors, with pseudocapacitance emerging as a promising method for accommodating Al3+ ions. Additionally, the review briefly mentions the potential utilization of Al anodes in lithium-ion batteries.