Atomically Transition Metals on Self‐Supported Porous Carbon Flake Arrays as Binder‐Free Air Cathode for Wearable Zinc−Air Batteries

• Published in: Advanced materials (Weinheim) 2019-04, Vol.31 (16), p.e1808267-n/a
• Main Authors: Ji, Dongxiao, Fan, Li, Li, Linlin, Peng, Shengjie, Yu, Deshuang, Song, Junnan, Ramakrishna, Seeram, Guo, Shaojun
• Format: Article
• Language: English
• Subjects: Acidification; binder‐free; Carbon; Carbon fibers; Carbonization; Catalysis; Catalytic activity; Chemical reactions; Deformation mechanisms; Electrocatalysts; Electrodes; electrospinning; Energy storage; Flakes; Materials science; Metal air batteries; Metal clusters; metal organic framework; Nanofibers; Organic chemistry; single atom catalysis; Stability; Storage capacity; Transition metals; Wearable technology; Zinc; Zinc-oxygen batteries; zinc–air battery
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.201808267

Metal single‐atom materials with their high atom utilization efficiency and unique electronic structures usually show remarkable catalytic performances in many crucial chemical reactions. Herein, a facile and easily scalable “impregnation‐carbonization‐acidification” strategy for fabricating a class of single‐atom‐anchored (including cobalt and nickel single atoms) monolith as superior binder‐free electrocatalysts for developing high‐performance wearable Zn–air batteries is reported. The as‐prepared single atoms, supported by N‐doped carbon flake arrays grown on carbon nanofibers assembly (M SA@NCF/CNF), demonstrate the dual characteristics of excellent catalytic activity (reversible oxygen overpotential of 0.75 V) and high stability, owing to the greatly improved active sites' accessibility and optimized single‐sites/pore‐structures correlations. Furthermore, wearable Zn–air battery based on Co SA@NCF/CNF air electrode displays superior stability under deformation, satisfactory energy storage capacity, and good practicality to be utilized as an integrated battery system. Theoretical calculations reveal a mechanism for the promotion of the catalytic performances on single atomic sites by lowering the overall oxygen reduction/evolution reaction barriers comparing to metal cluster co‐existing configuration. These findings provide a facile strategy for constructing free‐standing single‐atom materials as well as the engineering of high‐performance binder‐free catalytic electrodes. A class of single‐atom‐anchored hierarchically porous monoliths for flexible energy storage is prepared by a facile and easily scalable “impregnation–carbonization–acidification” strategy. It exhibits excellent bifunctional electrocatalytic activity for oxygen reduction/evolution reactions. Wearable zinc–air batteries based on this binder‐free monolith show low overpotential and high mechanical stability.