Designing FeCo‐NC‐Based Air Cathode for Sustained Zn‐Air Flow Batteries Through Equipping Electrocatalyst with Enriched Free Water Interface

ABSTRACT Zn‐air flow batteries (ZnAFB) are indispensable as strong contenders for future large‐scale energy storage, and further improvement of the batteries is directly limited by the catalytic activity of the cathode electrocatalysts, as well as the infrastructure of air cathodes. Herein, the FeCo‐NC‐based air cathode was delicately constructed with a catalytic layer of Fe 7 Co 3 @Fe‐N 3 &Co‐N 3 catalyst (Fe 8 Co 2 @FeCo‐NC sample), which was designed by introducing the Co species to the inexpensive Fe‐NC catalysts. By the verification of ab initio molecular dynamics (AIMD) and in situ Raman spectroscopy, we successfully achieved the manipulation of interfacial water with more enriched free water on the electrode surface by equipping an Fe 7 Co 3 alloy electron reservoir. As a result, the adsorption‐desorption‐transfer process of the active intermediates is much faster and more efficient without the limitation of a rigid hydrogen bond network. Unsurprisingly, the inexpensive Fe 8 Co 2 @FeCo‐NC electrocatalyst exhibited excellent bifunctional catalytic activity and reaction kinetics, resulting in excellent durability with a Zn‐air battery (ZnAB) power density of 208 mW cm −2 . Remarkably, its assembled ZnAFB with an optimized cathode structure harvests a discharge capacity of up to 56 mAh cm −2 and achieves an uninterrupted operating lifetime of up to 469 h at a discharge capacity of 28 mAh cm −2 .

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