Tailored Porous ZnCo₂O₄ Nanofibrous Electrocatalysts for Lithium–Oxygen Batteries

Lithium-oxygen batteries are considered a next-generation technology owing to their extremely high theoretical energy density despite many challenges such as low round-trip efficiency and poor cyclability. The air-cathode structure and pore properties play a key role in solving these problems. In this study, we fabricate ZnCo₂O₄ nanofibers and design a porous nanostructure using a facile electrospinning process and selective etching of ZnO as the cathode material in lithium-oxygen batteries. First, non-porous ZnCo₂O₄ nanofiber electrodes accomplish high catalytic activity and good cycling stability during 116 cycles with a limited capacity of 1000 mA h g⁻¹ at a current density of 500 mA g⁻¹. For enhanced catalytic activity and cyclability, ZnO included ZnCo₂O₄ nanofibers are prepared using a Zn-excess electrospun solution and porous ZnCo₂O₄ nanofibers are fabricated via selective etching of ZnO. Porous ZnCo₂O₄ nanofiber electrodes exhibit excellent electrocatalytic activity and cyclability for 226 cycles with a limited capacity of 1000 mA h g⁻¹ at a current density of 500 mA g⁻¹. The exceptional catalytic properties explain the synergistic effect of the one-dimensional nanostructure and porous structure with an appropriate pore diameter, providing a large active site and an efficient electron pathway during the Li₂O₂ formation/decomposition process.