Pyridinic-N exclusively enriched CNT-encapsulated NiFe interfacial alloy nanoparticles on knitted carbon fiber cloth as bifunctional oxygen catalysts for biaxially flexible zinc-air batteries

• Published in: Journal of materials chemistry. A, Materials for energy and sustainability Materials for energy and sustainability, 2024-04, Vol.12 (17), p.1185-1195
• Main Authors: Poudel, Milan Babu, Vijayapradeep, Subramanian, Sekar, Karthikeyan, Kim, Jong Seok, Yoo, Dong Jin
• Format: Article
• Language: English
• Subjects: Air; Batteries; Carbon; Carbon fibers; Carbon nanotubes; Catalysts; Cathodes; Chemical reduction; Cloth; Deformation; Electrocatalysts; Electrochemical analysis; Electrochemistry; Electron transfer; Electrons; Inert atmospheres; Intermetallic compounds; Iron compounds; Localization; Metal air batteries; Nanoalloys; Nanoparticles; Nickel; Nickel base alloys; Nickel compounds; Open circuit voltage; Oxidoreductions; Oxygen; Oxygen evolution reactions; Oxygen reduction reactions; Specific capacity; Stability; Tentacles; Zinc; Zinc-oxygen batteries
• ISSN: 2050-7488; 2050-7496
• DOI: 10.1039/d3ta07609a

The electrocatalytic oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) are the core reactions in reversible zinc-air batteries but are kinetically challenging because of their complex multi-electron transfer process. In this case, the exploration and rational design of non-precious bifunctional oxygen electrocatalysts with dense active sites and optimized electronic structures can facilitate favorable 4e − transfer. In this study, we report a highly reversible bifunctional electrocatalyst for flexible Zn-air batteries featuring pyridinic-N exclusively enriched carbon-nanotube-encased nickel-iron (NiFe) interfacial alloy nanoparticles derived from an LDH template on knitted carbon fiber cloth. The NiFe nanoparticles were catalytically released from NiFe-MOFs to form CNT tentacles when pyrolyzed in an inert atmosphere. XPS and XAS studies revealed the dominant presence of pyridinic-N, which reduces electron localization around NiFe centers and improves the interaction with oxygenated species. As a result, NiFe-N-CNT-KCC catalysts exhibited a low operating overpotential ( η 10 ) of 173 mV for the OER and a half-wave potential ( E 1/2 ) of 0.87 V for the ORR, which are superior to benchmark electrocatalysts. As an air cathode for zinc-air batteries, the NiFe-N-CNT-KCC-based battery showed an excellent electrochemical performance, with an open circuit voltage (OCV) of 1.55 V, high power density of 153 mW cm −2 , excellent specific capacity of 793.2 mA h g −1 , and long-term stability. Impressively, a solid-state flexible zinc-air battery with the NiFe-N-CNT-KCC cathode showed an admirable rate performance and exceptional mechanical stability under arbitrary bending and twisting conditions, showing great potential for practical implementation in next-generation high-power and high-energy-density batteries wearable applications. A highly reversible bifunctional electrocatalyst for flexible Zn air batteries was fabricated featuring pyridinic-N exclusively enriched CNT encased NiFe interfacial alloy nanoparticles derived from an LDH template on knitted carbon fiber cloth.