Materials challenges for aluminum ion based aqueous energy storage devices: Progress and prospects

Due to the shortage of lithium resources, current lithium-ion batteries are difficult to meet the growing demand for energy storage in the long run. Rechargeable aqueous aluminum ion (Al³⁺) electrochemistry has the advantages of abundant resources, high safety, environmental friendliness, and high energy/power density. It is, therefore an ideal choice for alternative energy storage devices. However, Al³⁺-based technology is still in the preliminary stage, and there are various challenges. In reality, its kinetics and reversibility have long been disturbed by the strong electrostatic field of Al³⁺ and the parasitic side reactions of aqueous electrolytes. This paper first summarizes the history of aqueous aluminum ion batteries/capacitors (AAIBs/AAICs) and analyzes the challenges faced by cathode, anode, and electrolyte. Then, the state-of-the-art research progress, design strategies, and limitations of the cathode, anode, electrolyte, and Al³⁺-based energy storage devices are comprehensively introduced, and their structure, performance, and reaction mechanisms are discussed. Finally, the future design of AAIBs/AAICs with long life, high reversibility, and high energy/power density has been prospected, and promising research directions are pointed out.