Study on leaf-shaped cobalt-based metal-organic frameworks synthesized by solvothermal method as high discharge current density air cathode catalyst for lithium-oxygen batteries

A type of leaf-shaped cobalt-based metal-organic framework material is synthesized by solvothermal method with 1.3:1 cobalt and terephthalic acid ratio and uses as the air electrode catalyst for lithium-oxygen batteries working at high discharge current density. Physical characterization displays that the interaction between cobalt and terephthalic acid can produce a crystal material and the different proportions have a certain influence on their structure and crystallinity. In addition, micromorphology with cobalt and terephthalic acid 1.3:1 shows a leaf-like structure, and synaptic structure on the leaf surface may be beneficial to improve the catalytic activity. Electrochemical tests present that air electrode using this leaf-like structure catalyst materials has good reversibility and the specific discharge capacities can achieve to 3573.90 mAh g−1 at 0.5 mA cm−2 current densities. However, compared with existing catalysts, these leaf-shaped catalyst materials have no obvious advantage in improving the cycle life.