高エネルギー密度と耐久性を備えた亜鉛空気フロー電池用FeCo-NCベース空気カソードの設計：触媒への豊富な自由水界面の装備

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 Fe₇Co₃@Fe-N₃&Co-N₃ catalyst (Fe₈Co₂@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 Fe₇Co₃ 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 Fe₈Co₂@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.