Scalable Electrospinning-Pyrolysis Fabrication of MOF-Derived Beaded Co/Co-Nx-C Nanofibers for High-Power and Long-Life Zn-Air Batteries

Abstract

The rational design of bifunctional electrocatalysts with abundant active sites and efficient charge/mass transport is crucial for Zn-air batteries. Here, we report a scalable electrospinning strategy to fabricate Co/N-doped carbon nanofibers (CNFs) with a beaded architecture derived from ZIF-67@PAN precursors. By precisely tuning the ZIF-67 loading, the intercluster spacing along the fibers can be controlled, yielding well-dispersed Co nanoparticles and Co-Nx moieties after pyrolysis. Critically, vertically stacked nanofibrous membranes enable scalable manufacturing. The optimized Co/Co-Nx-C@CNF-1.5 exhibits superior bifunctional activity (Delta E = 0.815 V), benefiting from balanced active-site density, rapid electron transport, and hierarchical porosity. Density functional theory calculations further reveal the microscopic origin that an appropriate spacing enables moderate electronic coupling between adjacent Co-based active sites, thereby optimizing the adsorption energetics of oxygen intermediates and facilitating ORR/OER kinetics. As an air cathode, the liquid Zn-air battery delivers a peak power density of 406.5 mW cm-2, an energy density of 976 Wh kg-1, and a long cycling stability of similar to 2143 h. The quasi-solid-state device also shows high power output, stable operation, and excellent flexibility. This work demonstrates a general electrospinning-pyrolysis approach to engineer MOF-derived self-supporting electrodes, bridging high-performance electrocatalysis with practical energy storage applications.