Microwave assisted synthesis for ϵ-MnO2 nanostructures on Ni foam as for rechargeable Li–O2 battery applications

Abstract

Lithium-air batteries exhibits high practical energy densities ranging from 1000 to 4000 Wh Kg−1, rendering them appealing for applications in portable electronic devices and electric vehicles. Nevertheless, they grapple with challenges like low charge–discharge efficiency, limited stability over multiple cycles, and electrode degradation stemming from undesirable side reactions, thus impeding their commercial market. In this study, ϵ-MnO2 petal-like nanostructures were synthesized on Ni foam via simple, microwave-assisted synthesis approach. The resulting ϵ-MnO2/Ni electrode demonstrated storage capacities (1982 mAh g−1 discharge capacity at 200 mA g−1) alongside enhanced cyclability and stability over 100 cycles, independent of discharge depth. This electrochemical performance can be attributed to its 3D morphology, oxygen defects, and the absence of side reactions from carbon-based additives. Overall, ϵ-MnO2/Ni electrode catalysts hold potential for realizing cost-effective Li-O2 based energy storage technologies.