First-Row Transition Metals for Catalyzing Oxygen Redox.

Rechargeable zinc-air batteries are widely recognized as a highly promising technology for energy conversion and storage, offering a cost-effective and viable alternative to commercial lithium-ion batteries due to their unique advantages. However, the practical application and commercialization of zinc-air batteries are hindered by the sluggish kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). Recently, extensive research has focused on the potential of first-row transition metals (Mn, Fe, Co, Ni, and Cu) as promising alternatives to noble metals in bifunctional ORR/OER electrocatalysts, leveraging their high-efficiency electrocatalytic activity and excellent durability. This review provides a comprehensive summary of the recent advancements in the mechanisms of ORR/OER, the performance of bifunctional electrocatalysts, and the preparation strategies employed for electrocatalysts based on first-row transition metals in alkaline media for zinc-air batteries. The paper concludes by proposing several challenges and highlighting emerging research trends for the future development of bifunctional electrocatalysts based on first-row transition metals.

Enhanced Copolymer Gel Modified by Dual Surfactants for Flexible Zinc-Air Batteries.

Zinc-air batteries using gels as carriers for electrolyte absorption have attracted extensive attention due to their flexibility, deformability, and high specific capacity. However, traditional mono-polymer gel electrolytes display poor mechanical properties and low ionic conductivity at wide-window temperatures. Here, the enhanced gel polymer (PAM-F/G) modified by dual surfactants is present by way of pluronic F127 and layered graphene oxide introduced into the polyacrylamide (PAM) matrix. The gel electrolyte procured by absorbing 6 M KOH exhibits improved mechanical characteristics, temperature adaptability, and a satisfactory ionic conductivity (276 mS cm-1). The results demonstrate that a flexible zinc-air battery assembled by PAM-F/G electrolyte outputs a high power density (155 mW cm-2) and can even operate reliably (>40 h) at -20 °C. These findings are available for promoting the research and popularization of flexible zinc-air batteries with high performance.

Magnetic zinc-air batteries for storing wind and solar energy.

With the consensus on carbon peak and neutrality around the globe, renewables, especially wind and solar PV will grow fast. Correspondingly, the batteries for renewables would be scheduled to meet the requirements of performance, lifetime, cost, safety, and environment. Rechargeable zinc-air battery is a promising candidate for energy storage. However, the lifetime and power density of zinc-air batteries remain unresolved. Here we propose a concept of magnetic zinc-air batteries to achieve the demand of the next generation energy storage. Firstly, an external magnetic field can effectively inhibit dendrite growth of the zinc depositing layer and expel H2 or O2 bubbles away from the electrode's surface, extending the battery life. Secondly, magnetic fields can promote electrons, ions, and O2 transfer, enhancing power density of zinc-air batteries. Lastly, four schemes to generate magnetic fields for zinc-air batteries are exhibited to fulfill battery energy storage demand of high performance and long service life.

A high-performance Al-air fuel cell using a mesh-encapsulated anode via Al-Zn energy transfer.

Aluminum-air fuel cells attract more attention because of their high specific energy, low cost, and friendly environment. However, the problems of hydrogen evolution corrosion and low anode efficiency of aluminum-air fuel cells remain unresolved. Herein, we propose an aluminum-air fuel cell using a mesh-encapsulated anode, where the energy redistribution can be achieved and the discharge performance of the fuel cell can be highly improved. The results show that the highest inhibition efficiency is 73.930% when the aluminum plate is immersed in 6 M potassium hydroxide solution containing 100% zinc oxide. The highest anode efficiency is up to 61.740% when the fuel cell using a mesh-encapsulated anode is discharged at 20 mA/cm2, which is more than 2 times than that of no mesh, and the highest capacity can reach 1839.842 mAh/g, which is 101.623% higher than before optimization. Thus, our studies are very instructive for the large-scale application of aluminum-air fuel cells.