The global market of flexible/printed and organic electronics is about 41 billion dollars in 2020, which is expected to reach over 74 billion dollars in 2030 according to the relevant reports by IDTechEx. [3] As for the development and expansion toward practical application, flexible/wearable electronics urgently request for flexible energy sources and power devices with high specific energy density and long lifetime. During the past decade, a variety of flexible energy harvesting/conversion (e.g., solar cells, nanogenerators) and energy storage devices (e.g., batteries, supercapacitors, hybrid batteries) have dedicatedly progressed and gained ongoing recognition for future wearable applications. [4][5][6] Among those promising renewable energy technologies, rechargeable lithium-ion batteries (LIBs) have received widespread adoptions for power supplies ranging from mobile/portable electronics to plug-in/ hybrid electric vehicles because of their high working voltage, appreciable energy density, easy use, and ecofriendliness. [7] Flexible LIBs became one of the potential options for powering flexible electronics. With further advance, flexible LIBs are plagued by their limited energy density, deficient safety, and relatively high cost of electrode materials (e.g., lithium, cobalt). In this case, alternative battery technologies, especially metal-air batteries gain immense attention (Table 1). [8,9] Metal-air batteries (MABs) own 2-10 times higher specific energy than current LIBs (200-250 Wh kg −1 ) due to the direct utilization of oxygen from the atmosphere within a halfopen device system. Alongside, rechargeable MABs have more freedom in metallic anodes such as lithium, sodium, potassium, zinc, aluminum and magnesium, etc., where the latter three-based MABs are compatible with aqueous alkaline electrolytes and also intrigued numerous interest. [10][11][12] Given the high theoretical specific energy (1218 Wh kg −1 , 6136 Wh L −1 ), low fabrication cost, high operational safety and environmental benignancy, aqueous zinc-air batteries (ZABs) show far more practical prospect for new-generation energy storage sources. [11] Figure 1 illustrates the brief chronology of the development of ZABs. Dating back to 1878, the first The strong propulsion stem from flexible/wearable electronics has greatly stimulated the development of miniaturized and high-performance rechargeable batteries with adaptable shape. Flexible zinc-air batteries (FZABs), which exhibit high theoretical energy density (1218 Wh kg −1 ), low cost, environmental benignancy, and admirable operational safety, have been widely recognized as one of the promising portable powers to serve future wearable electronics for ubiquitous application. During the past five years, the energy/ power density and cycling stability of FZABs have gained significant improvement largely due to the rational construction of high-efficiency bifunctional air electrodes. Herein, the recent progress of integrated binder-free bifunctional oxygen electrodes is overviewed via elaborate ...
