Co/Zn-based bimetallic MOF-derived hierarchical porous Co/C composite as cathode material for high-performance lithium-air batteries

Structural optimization and electrocatalyst utilization in air cathodes have been identified as two major factors affecting the overall performance of a lithium-air battery. Herein, a cobalt@porous carbon composite, Co@C(700-1000) was obtained by facile annealing of a Co/Zn-bimetallic metal-organic framework (MOF). In the Co/Zn-MOF, cobalt cluster was used as a precursor of the catalyst and zinc cluster as a sacrificial template to generate meso- and macropores. The lithium-air battery with the assembled Co@C(700-1000) air cathode revealed a specific capacity as high as 4 mAh cm⁻². Furthermore, the battery exhibited high cycling stability up to 67 cycles (limited capacity of 0.5 mAh cm⁻²). The high cell performance can be in relation to the catalytic activity of uniformly disseminated cobalt nanoparticles in the porous carbon matrix and the rapid diffusion and transport of Li⁺ and O₂ owing to the optimized pore-distribution characteristics. Using a bimetallic MOF-derived material, this study sheds fresh light on the design of an air cathode for lithium-air batteries.