A morphology, porosity and surface conductive layer optimized MnCo₂O₄ microsphere for compatible superior Li⁺ ion/air rechargeable battery electrode materials

Abstract

Uniform surface conductive layers with porous morphology-conserved MnCo₂O₄ microspheres are successfully synthesized, and their electrochemical performances are thoroughly investigated. It is found that the microwave-assisted hydrothermally grown MnCo₂O₄ using citric acid as the carbon source shows a maximum Li⁺ ion lithiation/delithiation capacity of 501 mA h g⁻¹ at 500 mA g⁻¹ with stable capacity retention. Besides, the given microsphere compounds are effectively activated as air cathode catalysts in Li-O-2 batteries with reduced charge overpotentials and improved cycling performance. We believe that such an affordable enhanced performance results from the appropriate quasi-hollow nature of MnCo₂O₄ microspheres, which can effectively mitigate the large volume change of electrodes during Li⁺ migration and/or enhance the surface transport of the LiOx species in Li-air batteries. Thus, the rationally designed porous media for the improved Li⁺ electrochemical reaction highlight the importance of the 3D macropores, the high specific area and uniformly overcoated conductive layer for the promising Li⁺ redox reaction platforms.