Unravelling the Tip Effect of Oxygen Catalysis in Integrated Cathode for High-Performance Flexible/Wearable Zn–Air Batteries

• Published in: Advanced fiber materials (Online) 2024-10, Vol.6 (5), p.1470-1482
• Main Authors: Shen, Yirun, Mao, Haoning, Li, Chen, Li, Keer, Liu, Yi, Liao, Jihai, Zhang, Shengsen, Fang, Yueping, Cai, Xin
• Format: Article
• Language: English
• Subjects: Bimetals; Carbon; Carbon nanotubes; Catalysis; Catalysts; Chemical synthesis; Chemistry and Materials Science; Density functional theory; Efficiency; Electrocatalysts; Electrochemical analysis; Electrochemistry; Electrolytes; Electrons; Energy consumption; Energy storage; Heterostructures; Intermetallic compounds; Iron compounds; Kinetics; Materials Engineering; Materials Science; Metal air batteries; Molecular dynamics; Morphology; Nanoalloys; Nanoscale Science and Technology; Nickel compounds; Nitrogen; Oxygen enrichment; Oxygen evolution reactions; Polymer Sciences; Reaction kinetics; Renewable and Green Energy; Research Article; Seeds; Specific energy; Spectrum analysis; Textile Engineering; Transition metals; Zinc-oxygen batteries
• ISSN: 2524-7921; 2524-793X
• DOI: 10.1007/s42765-024-00425-5

The exploration of high-efficiency transition metal–nitrogen–carbon (M–N–C) catalysts is crucial for accelerating the kinetics of oxygen reduction/oxygen evolution reactions (ORR/OER). Fine-tuning the distribution of accessible metal sites and the correlated triphase interfaces within the M–N–C catalysts holds significant promise. In this study, we present an integrated electrocatalyst comprised of tip-enriched NiFe nanoalloys encapsulated within N-doped carbon nanotubes (NiFe@CNTs), synthesized using an in-situ wet-electrochemistry mediated approach. The well-defined NiFe@CNTs catalyst possesses a porous heterostructure, synergistic M–N x –C active sites, and intimate micro interfaces, facilitating accelerated redox kinetics. This leads to exceptional OER/ORR activities with a low overall Δ E of 630 mV. Experimental results and density functional theory calculations unveil the predominant electronic interplay between the apical bimetallic sites and neighboring N-doped CNTs, thereby enhancing the binding of intermediates on NiFe@CNTs. Molecular dynamics simulations reveal that the local gas–liquid environment surrounding NiFe@CNTs favors the diffusion/adsorption of the OH − /O 2 reactants. Consequently, NiFe@CNTs contribute to high-performance aqueous Zn–Air batteries (ZABs), exhibiting a high gravimetric energy density (936 Wh kg Zn –1 ) and superb cycling stability (> 425 h) at 20 mA cm –2 . Furthermore, solid-state ZABs based on NiFe@CNTs demonstrate impressive electrochemical performance (e.g., peak power density of 108 mW cm −2 , specific energy of 1003 Wh kg Zn –1 ) and prominent flexibility. This work illuminates a viable strategy for constructing metal site-specific, cobalt-free, and integrated M–N–C electrocatalysts for multifunctional catalysis and advanced/flexible energy storage applications. Graphical Abstract