High‐Density Accessible Iron Single‐Atom Catalyst for Durable and Temperature‐Adaptive Laminated Zinc‐Air Batteries

Abstract Designing single‐atom catalysts (SACs) with high density of accessible sites by improving metal loading and sites utilization is a promising strategy to boost the catalytic activity, but remains challenging. Herein, a high site density (SD) iron SAC (D‐Fe‐N/C) with 11.8 wt.% Fe‐loading is reported. The in situ scanning electrochemical microscopy technique attests that the accessible active SD and site utilization of D‐Fe‐N/C reach as high as 1.01 × 10²¹ site g⁻¹ and 79.8%, respectively. Therefore, D‐Fe‐N/C demonstrates superior oxygen reduction reaction (ORR) activity in terms of a half‐wave potential of 0.918 V and turnover frequency of 0.41 e site⁻¹ s⁻¹. The excellent ORR property of D‐Fe‐N/C is also demonstrated in the liquid zinc‐air batteries (ZABs), which exhibit a high peak power density of 306.1 mW cm⁻² and an ultra‐long cycling stability over 1200 h. Moreover, solid‐state laminated ZABs prepared by presetting an air flow layer show a high specific capacity of 818.8 mA h g⁻¹, an excellent cycling stability of 520 h, and a wide temperature‐adaptive from −40 to 60 °C. This work not only offers possibilities by improving metal‐loading and catalytic site utilization for exploring efficient SACs, but also provides strategies for device structure design toward advanced ZABs.