Anode Materials for Rechargeable Aqueous Al‐Ion Batteries: Progress and Prospects

Abstract

Rechargeable aqueous Al‐ion batteries (AIBs) have attracted more attention as potential energy storage systems due to their low cost, high safety, and environmental friendliness. As a crucial role in AIBs, efforts have been devoted to exploring suitable anode material over the past decade. Herein, the latest advances in using Al3+ intercalation and Al deposition anode materials are critically discussed, including current challenges, reaction mechanisms, and achievable electrochemical properties. This review aims to provide a summary of the strategies proposed to date to overcome the anode issues restricting the present rechargeable aqueous AIBs. Emphasis is placed on alleviating the passivation and corrosion problems of metallic Al anode for realizing rechargeable aqueous AIBs with high energy density. Finally, some suggestions are put forward for the guidance of future research directions on the optimization of anode materials in the expectation of promoting further development of rechargeable aqueous AIBs.

Solid State Zinc and Aluminum ion batteries: Challenges and Opportunities

“…Al ion batteries using liquid-based electrolytes can be categorized into two types: 1) aqueous electrolyte, and 2) non-aqueous ionic liquid-based electrolyte mixed with AlCl 3 salts. [6] Ionic liquids are in liquid phase with salts at room temperature and can serve as ionic fluids with superior ionic conductivity. Ionic liquid-based electrolytes with AlCl 3 salts have problems with moisture sensitivity, acidic corrosive electrolyte and electrolyte leakage during battery cycling.…”

“…As the standard potential of Al/Al 3 + is lower than the HER potential, HER is thermodynamically more dominant than Al deposition, lowering the coulombic efficiency. [6] At the same time, the aqueous electrolyte decomposition via HER will result in the increase of electrolyte pH. Thus, the electrolyte will corrode the Al metal anode, further forming an aluminum hydroxide layer and preventing the Al ion deposition.…”

“…a higher theoretical volumetric capacities of Zn metal (5854 mAh cm À 3 ), [5] and Al metal (8056 mAh cm À 3 ) over Li metal (2061 mAh cm À 3 ). [6] These merits of aqueous ZIBs and AIBs make them promising alternatives for LIBs in wearable devices.…”

“…Second, a narrow electrochemical stability window (~1.23 V) of water also increases the risk of oxygen evolution reaction (OER). [5,6] Furthermore, aqueous zinc ion batteries suffer from severe zinc dendrite growth on the anode metal, [7] and dissolution of cathode materials. [8] On the other hand, in the aqueous AIBs, a passivation layer (Al 2 O 3 ) will spontaneously form on the Al metal anode, hindering a reversible Al 3 + stripping/plating.…”

“…[8] On the other hand, in the aqueous AIBs, a passivation layer (Al 2 O 3 ) will spontaneously form on the Al metal anode, hindering a reversible Al 3 + stripping/plating. [6] Replacing aqueous electrolytes with solid-state or quasisolid-state polymer electrolytes in these systems can alleviate many of the discussed problems. These electrolytes usually contain little or no water content and own solid-solid interfaces between electrodes.…”