Challenges and Strategies of Aluminum Anodes for High-Performance Aluminum-Air Batteries.

Aluminum-air battery (AAB) is a promising candidate for next-generation energy storage/conversion systems due to its cost-effectiveness and impressive theoretical energy density of 8100 Wh kg-1, surpassing that of lithium-ion batteries. Nonetheless, the practical applicability of AABs is hampered by the occurrence of serious self-corrosion side reactions and substantial capacity loss, resulting in suboptimal anode utilization. Consequently, improving the anode utilization to facilitate the construction of high-performance AABs have attracted widespread attention. Herein, the fundamentals and strategies to enhance aluminum anode utilization are reviewed from modifications of aluminum anodes and electrolytes. This comprehensive review may provide a scientific tool for the development of novel AABs in the future.

Quasi-Solid-State Aluminum-Air Batteries with Ultra-high Energy Density and Uniform Aluminum Stripping Behavior.

Aqueous aluminum-air batteries are attracting considerable attention with high theoretical capacity, low-cost and high safety. However, lifespan and safety of the battery are still limited by the inevitable hydrogen evolution reaction on the metal aluminum anode and electrolyte leakage. Herein, for the first time, a clay-based quasi-solid-state electrolyte is proposed to address such issues, which has excellent compatibility and a liquid-like ionic conductivity. The clay with uniform pore channels facilitates aluminum ions uniform stripping and reduces the activity of free H2 O molecules by reconstructing hydrogen bonds network, thus suppressing the self-corrosion of aluminum anode. As a result, the fabricated aluminum-air battery achieves the highest energy density of 4.56 KWh kg-1 with liquid-like operating voltage of 1.65 V and outstanding specific capacity of 2765 mAh g-1 , superior to those reported aluminum-air batteries. The principle of constructing quasi-solid-state electrolyte using low-cost clay may further promote the commercialization of aluminum-air batteries and provide a new insight into electrolyte design for aqueous energy storage system.

Regulating solvation and interface chemistry enables advanced aluminum-air batteries.

The main challenge for developing aqueous aluminum-air batteries with high mass-specific capacity depends on the inhibition of the parasitic hydrogen evolution reaction. Herein, a regulation strategy of solvation and interface chemistry has been proposed by introducing organic methylurea (MU) and inorganic stannous chloride (SnCl2) to the alkaline electrolyte, which can modulate the solvent structure and electrode/electrolyte interface and endow the aqueous aluminum-air battery with an outstanding mass-specific capacity of 2625 mA h g-1 at 50 mA cm-2.