Air Electrodes for Flexible and Rechargeable Zn−Air Batteries

Abstract

Rechargeable Zn−air batteries (ZABs) have attracted increasing attention as one of the most promising future energy power sources due to their relatively high specific energy density, environmental friendliness, safety, and low cost. In particular, flexible ZABs are desirable for portable and wearable electronic devices, in which the cathode can utilize air directly from the atmosphere with significantly enhanced energy density. Therefore, the air electrode consisting of oxygen electrocatalysts is the most critical component in flexible ZABs, significantly governing the overall battery performance and cost. This review highlights recent achievements in designing efficient oxygen electrocatalysts and air electrodes for rechargeable and flexible ZABs. First, the most significant innovations of recent battery configurations to improve flexibility and battery performance are introduced. Then, oxygen electrocatalysts developed for fabricating high‐performance air cathodes in flexible ZABs in terms of catalyst properties, unique nanostructures, and morphologies are emphasized. Furthermore, effective architectures of air electrodes are discussed to highlight structural stability and charge/mass transports for improving battery performance. Finally, a perspective for designing durable and high‐power air electrodes for flexible ZABs is provided, aiming to summarize current challenges and possible solutions to commercialize the exciting battery technology eventually.

Challenges for large scale applications of rechargeable Zn–air batteries

“…And the latter mainly catalyzes the oxygen evolution reaction (OER) of the charging process and the oxygen reduction reaction (ORR) of the discharging process occurring at the Zn–air battery cathode, which are two key steps of the entire battery reaction. 13,101 However, the reaction kinetics are too sluggish and the performance is generally poor in non-alkaline electrolytes, which are more in line with the application trend, and they are susceptible to the loss of catalytic activity in ambient air due to poisoning by certain components in air such as carbon dioxide. Therefore, the goal of further research is to find better air electrode catalysts with higher catalytic activity and stable performance.…”

Rechargeable Micro‐Batteries for Wearable and Implantable Applications

“…Due to the use of liquid electrolytes in commercial Li‐ion battery systems, there are many potential safety hazards such as toxic electrolyte leakage, corrosion, combustion, and even explosion. [ 99 ] Other emerging battery systems, such as Zn‐air batteries, usually use high concentration strong bases electrolytes, [ 100–102 ] which may also cause serious corrosions or burns. Consequently, these battery systems usually need to be tightly packaged to prevent electrolytes from leakage.…”

Compressible Zn–Air Batteries Based on Metal–Organic Frameworks Nanoflake‐Assembled Carbon Frameworks for Portable Motion and Temperature Monitors

“…[16][17][18][19][20][21] Besides, flexible Zn-air batteries (FZABs) exhibit lightweight, favorable structural stability, thus are one of the most promising candidates as power source for portable and wearable sensors. [22][23][24][25][26] As the key component in FZABs, air electrodes are required to be active for oxygen electrocatalytic reaction, [27] but also have good mechanical flexibility and stability for wearable applications. [28] Recently, FZABs have been reported as power sources which successfully driven various portable sensors, such as pulse, [29] gas, [30] temperature and humidity, [31] and even the highly integrated sensor for the detection of ambient light, gyroscope, humidity, and so on.…”

“…[ 16–21 ] Besides, flexible Zn–air batteries (FZABs) exhibit lightweight, favorable structural stability, thus are one of the most promising candidates as power source for portable and wearable sensors. [ 22–26 ]…”